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HM 22 2nd Ed.: Major Fleet-versus-Fleet

Operations in the Pacific War, 1941–1945

Milan Vego

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COVER

Units of the 1st Marine Division in LVT Assault Craft 

Pass the Battleship USS North Carolina off Okinawa, 1 

April 1945, by the prolific maritime artist John Hamilton 

(1919–93). Used courtesy of the Navy Art Collection, 

Washington, D.C.; the painting is currently on loan to 

the Naval War College Museum. In the inset image and 

title page, Vice Admiral Raymond A. Spruance ashore on 

Kwajalein in February 1944, immediately after the seizure 

of the island, with Admiral Chester W. Nimitz. Naval 

History and Heritage Command photograph NH62233. 
1941–1945 Major Fleet-versus-Fleet Operations 

in the Pacific War
U.S. GOVERNMENT

OFFICIAL EDITION NOTICE

Use of ISBN Prefix

This is the Official U.S. Government edition of this publication 

and is herein identified to certify its authenticity. ISBN 

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ISBN: 978-1-935352-44-0
NAVAL WAR COLLEGE HISTORICAL MONOGRAPH SERIES NO. 22 

2ND EDITION

The historical monographs in this series are book-length studies of the history of 

naval warfare, edited historical documents, conference proceedings, and bibliographies that are based wholly or in part on source materials in the Historical Collection of the Naval War College.

The editors of the Naval War College Press express their special gratitude to all 

the members of the Naval War College Foundation, whose generous financial support for research projects, conferences, and printing has made possible the publication of this historical monograph.
To the U.S. naval aviators who fought in the Pacific War, 1941–45, 

for their extraordinary courage and sacrifices.
NAVAL WAR COLLEGE PRESS

NEWPORT, RHODE ISLAND

FIRST EDITION PUBLISHED 2014

SECOND EDITION 2016

1941–1945 Major Fleet-versus-Fleet Operations 

in the Pacific War

Second Edition

Milan Vego
The contents of this volume represent the views of the author. 

His opinions are not necessarily endorsed by the Naval War 

College or by any other agency, organization, or command of 

the U.S. government.

Printed in the United States of America

Historical Monograph Series

Library of Congress Cataloging-in-Publication Data

Names: Vego, Milan N., author.

Title: Major fleet-versus-fleet operations in the Pacific war, 1941-1945 /

Milan Vego.

Description: 2nd edition. | Newport, Rhode Island : Naval War College Press,

2016. | Series: Naval War College historical monograph series ; no. 22 |

Includes bibliographical references.

Identifiers: LCCN 2016026042 | ISBN 9781935352440

Subjects: LCSH: World War, 1939-1945—Campaigns—Pacific Ocean. | World

War, 1939-1945—Naval operations, American. | World War, 1939-1945—

Naval operations, Japanese. | Coral Sea, Battle of the, 1942. | Midway, Battle

of, 1942. | Philippine Sea, Battle of the, 1944 (June 19-21) | Leyte Gulf,

Battle of, Philippines, 1944.

Classification: LCC D767 .V45 2016 | DDC 940.54/26—dc23

LC record available at https://lccn.loc.gov/2016026042

NAVAL WAR COLLEGE PRESS

Code 32

Naval War College 

686 Cushing Road

Newport, R.I. 02841-1207
TABLE OF CONTENTS

 Foreword, by Carnes Lord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ix

 Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xi

 List of Acronyms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

 List of Maps, Sidebars, and Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

I. The Port Moresby–Solomons Operation and Allied Reaction, 

27 April–11 May 1942 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

II. The Midway-Aleutians Operation, 25 May–14 June 1942 . . . . . . . . . . . . . . . . . . . . 81

III. Japanese A-Go Operation (Battle of the Philippine Sea), 13–22 June 1944: 

Situation and Theater. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

IV. Japanese A-Go Operation (Battle of the Philippine Sea), 13–22 June 1944: 

Planning and Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209

V. Japanese A-Go Operation (Battle of the Philippine Sea), 13–22 June 1944: 

Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243

VI. Japanese A-Go Operation (Battle of the Philippine Sea), 13–22 June 1944: 

Conclusions and Operational Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303

 About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315

 Titles in the Series. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

FOREWORD

In the fall of 2008, the Naval War College Press published Milan Vego’s Major Naval 

Operations as Newport Paper 32. The present work represents a sequel of sorts to 

that study, or perhaps more precisely, an elaboration on it in the form of detailed 

studies of three major naval operations of World War II. These three, initiated by 

imperial Japan, took place in the Pacific and resulted in the battles of the Coral Sea, 

Midway/Aleutians, and the Philippine Sea. All the cases provide ample background 

on the geographic and strategic context of the operations, as well as an account 

of the unfolding of the action utilizing much primary source material in, especially, American and Japanese archives. Finally, and most valuably, Vego in each 

case identifies lessons learned from it for a proper appreciation of naval operational 

art. As Vego will argue, these lessons are of more than merely historical interest for 

today’s U.S. Navy.

Dr. Milan Vego is a professor in the Joint Military Operations Department of 

the Naval War College. He is the author of Operational Art (2001) and Joint Operational Warfare (2008), an authoritative textbook currently in use as part of the 

department’s teaching curriculum, as well as numerous articles for military publications in this country and abroad.

Carnes Lord

Director, Naval War College Press

PREFACE

The idea for this book came from Dr. Carnes Lord, director of the Naval War College Press, in the spring of 2012. He suggested that it would be a good thing to have 

a historical monograph on selected major naval operations. I agreed, because the 

new book would be a sequel to my Major Naval Operations, published as Newport 

Paper 32 in 2008. The book would provide an analysis from the operational-art 

perspective of selected major naval operations conducted in World War II. The 

plan was to include one of my articles (on the Port Moresby–Solomons operation) 

that have appeared in the Naval War College Review, plus two new case studies: the 

Midway-Aleutians and A-Go operations. 

The main purpose is to stimulate interest in the study of the theory and practice 

of major naval operations. This is an area that the U.S. Navy and other Western navies have given short shrift. Too much focus is given to “strike operations”—that is, 

tactics—while operational art is either ignored or dismissed as irrelevant. Yet major 

naval operations should form the very heart of a doctrine for operational war at sea. 

Another purpose of this monograph is to provide a source for studying major naval 

operations as part of the curriculum of the Joint Military Operations Department 

here at the Naval War College. 

The main body of this work comprises two parts. The first part deals with major fleet-versus-fleet operations conducted during the Pacific War, 1941–45. These 

clashes resulted from imminent amphibious landings on defended shores—the Port 

Moresby and Midway-Aleutians operations. The second part (chapters 3 through 

6) describes an operation fought in defense (by one side, in each case) of ground 

forces that had already landed on an enemy-held shore (the A-Go operation). 

The internal organization of each chapter (and of part 2, taken together) is 

roughly identical. Any major operation is planned and executed within a much 

broader and more important framework determined by policy and strategy. Hence, 

the strategic setting for each major naval operation is described in some detail. 

For each case study there is a section on the physical features and weather/climate 
xii MAJOR FLEET

VERSUSFLEET OPERATIONS IN THE PACIFIC WAR, 19411945

in the theater of operation. Another section analyzes the various elements of the 

theater’s geography (positions, distances, naval/air bases, lines of operation, lines of 

communications, etc.). Command structures are then addressed; a sound theater 

command structure or organization is a key prerequisite of command and control. 

Further, decisions on and the subsequent planning and execution of major naval 

operations are largely based in the accuracy, timeliness, and relevance of information available to the commanders. One of the greatest advantages the Allies possessed in both the European and the Pacific theaters was their ability to intercept 

and then decode and then read most of the enemy’s radio messages. Hence, each 

case study contains a detailed description and analysis of what the opposing operational commanders knew at the time they made decisions. The bulk of each case 

study (chapter or part) is devoted to analysis of the opposing plans and their execution. Each ends with an extensive conclusion and outline of operational lessons. 

No study of any major operation or campaign is of practical use unless its possible 

operational lessons are identified and studied. Finally, each case study is accompanied by several detailed maps of the respective theater and phases of the operation. 

In writing this monograph, emphasis was given to the use of primary sources 

held at the Military Branch, National Archives and Records Administration, in 

College Park, Maryland. 

This work would not have been possible without the cooperation and help of 

many people. My heartfelt thanks are to Dr. Lord for his staunch and consistent 

support for the project. I am also very grateful to Capt. Alan Abramson, USN, 

chairman of the Joint Military Operations Department, and his executive officer, 

Professor (and Capt., USN [Ret.]) Fred Horne. Thanks to them I was released from 

various administrative duties and departmental meetings to have more time for 

this project. 

I am also greatly indebted for a superb job and great patience to Pelham Boyer 

of the Naval War College Press, for copyediting and preparing the manuscript and 

previous articles for proofs; to Mr. John Lanzieri, for typesetting; to Ms. Shannon 

Cole and Mr. Albert F. Fassbender III, for careful proofreading; and to Mr. Art 

Lamoureux, who prepared all the maps and figures. Finally, and not the least, I 

am grateful for consistent support provided by Ms. Elizabeth Davis, the Visual 

Communications Department head, and Mr. Jeremiah Lenihan, lead specialist in 

the Desktop Publishing Division. 

Milan Vego

Joint Military Operations Department

Naval War College, Newport, Rhode Island 
ACRONYMS 

AA antiaircraft

AAF Air Attack Force; [U.S.] Army Air Forces

ABC American, British, Canadian

AGS Army General Staff

AirRon air squadron

ANZAC Australia–New Zealand Army Corps

ATIS Allied Translator and Interpretation Section

BatDiv battleship division

BB battleship

CA heavy cruiser

CAP combat air patrol

CarDiv carrier division

CCS Combined Chiefs of Staff

CENTPAC Central Pacific Area

CG commanding general

CINC commander in chief

CINCPac Commander in Chief, Pacific Fleet

CINCPOA Commander in Chief, Pacific Ocean Areas

CL light cruiser

CNAS naval air station commander

CNO Chief of Naval Operations

COM 14 Commander, 14th Naval District

COMINCH Commander in Chief, United States Fleet

COMINT communications intelligence

COMPATWINGSPAC Commander, Patrol Wings, Pacific

COMSWPA Commander, Southwest Pacific Area

CruDiv cruiser division

CTF Commander, Task Force

DD destroyer

DesDiv destroyer division

DesRon destroyer squadron

DF direction finding
xiv MAJOR FLEET

VERSUSFLEET OPERATIONS IN THE PACIFIC WAR, 19411945

DI decryption intelligence

HQ headquarters

IGHQ Imperial General Headquarters

IJN Imperial Japanese Navy

JCS Joint Chiefs of Staff

JICPOA Joint Intelligence Center Pacific Ocean Area

JSSC Joint Strategic Survey Committee

MTB motor torpedo boat

NEI Netherlands East Indies 

NGS Naval General Staff

NORPAC Northern Pacific Area

Op-20G Navy Radio Intelligence Section

OPLAN operation plan

OpNav (CNO staff)

PBM Martin patrol bomber (seaplane) 

POA Pacific Ocean Areas

RAAF Royal Australian Air Force

RAN Royal Australian Navy

RDF radio direction finding

SNLF Special Naval Landing Force

SOPAC South Pacific; Southern Pacific Area

SubDiv submarine division

SubGru submarine group

SubRon submarine squadron

SWPA Southwest Pacific Area

TF task force

TG task group

TI traffic intelligence

TU task unit
LIST OF MAPS, SIDEBARS, AND FIGURES

Maps

Chapter I

1. Operating Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2. Structure of the POA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3. Japanese Operational Idea (Scheme) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4. The Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Chapter II

5. The Theater and Its Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

6. Japanese Operational Idea (Scheme) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

7. Movements of the Opposing Forces and Searches until 2400, 

3 June 1942. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

8. Deployment of the Opposing Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

9. The Midway Phase, 0900–2400, 4 June 1942 . . . . . . . . . . . . . . . . . . . . . . . 141

10. The Aleutians Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

Chapter III 

11. Japanese Mandated Islands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

12. Japanese Southern Defense Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Chapter V 

13. First Mobile Force: Deployment and Approach Phase, 

13–17 June 1944 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

14. Movements and Searches of the Opposing Forces, 

17–19 June 1944 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

15. Final Approach, 19 June 1944 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

16. The Climax, 0300–1500, 19 June 1944 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

Sidebars

Chapter I 

 Japanese Order of Battle, May 1942 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

 Allied Task Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Chapter II

 Japanese Task Organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

 U.S. Task Organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
xvi MAJOR FLEET

VERSUSFLEET OPERATIONS IN THE PACIFIC WAR, 19411945

Chapter IV

 Japanese Order of Battle, May 1942 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220

 U.S. Order of Battle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

 Allied Landing on Biak and Japanese Reaction, 

27 May–11 June 1944 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

 Map—KON Operation: Japanese Naval Movements, 

30 May–11 June 1944 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

Chapter V

 Spruance’s Decision at 0038, 19 June . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

Figures 

Chapter V

1. First Mobile Force: Battle Disposition #1 (Mod), 19 June 1944 . . . . . . . . 279

2. TF 58’s Battle Formation, 19 June 1944 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
INTRODUCTION

The term “major operation” is used in the U.S. military to make a clear distinction 

between an operation aimed at an operational objective and one involving almost 

any scale and type of employment of combat forces, including logistics and training. In contrast, the term “operation” as used in most European militaries, notably 

the German and the Soviet/Russian, is essentially identical in its meaning to the 

term “major operation” as used by the United States. 

In generic terms, a major naval operation consists of a series of related major 

and minor naval tactical actions conducted by diverse combat arms and meant to 

accomplish an operational (sometimes partly strategic) objective in a given maritime theater. A major naval operation is planned and conducted by a single commander in accordance with an operational idea (scheme) and a common plan. Major naval operations are normally integral parts of maritime or land campaigns, 

but they can sometimes be conducted outside the framework of a campaign. In the 

littorals, major naval operations are planned and conducted with the participation 

of combat arms of other services, air forces in particular. 

By accomplishing an operational objective, a major naval operation drastically 

changes the operational situation in that part of the maritime theater. However, if 

it is only partially successful, the operational situation is most likely to remain as 

it was. A major naval operation can also have a strategic effect, although its main 

objective is operational in scale.

The best and most proven way of avoiding attrition at the operational or strategic 

level is by planning and executing major operations or campaigns, respectively. By 

conducting a major naval operation, the stronger side at sea can defeat the weaker 

side in an ocean/sea area and within a time frame of its own choosing. Major naval 

operations are normally planned and conducted when decisive results must be accomplished in the shortest possible time and with the least loss.1

 Successful major 

naval/joint operations can contribute considerably to shortening a war at sea. 
xviii MAJOR FLEET

VERSUSFLEET OPERATIONS IN THE PACIFIC WAR, 19411945 

“Tactical actions” in a major naval operation can be fought on the surface, underwater, in the air, and, in some cases, on the coast. Their results are not just a 

simple arithmetic sum; tactical actions are all related and conducted within a given 

operational framework. A tactical action fought outside the framework of a major 

naval operation would generally not contribute to the accomplishment of the assigned operational objective and therefore would represent a waste of resources 

and sorely needed time. 

Naval tactical actions can range from actions without use of weapons, such as 

patrolling and surveillance, to attacks, strikes, raids, engagements, and finally naval 

battles. As the term implies, they are aimed at accomplishing tactical objectives in 

a given part of a maritime theater. In some cases, a series of diverse tactical actions 

conducted over time can lead to the accomplishment of an operational objective. 

A major naval operation is not an artificial construct but a result of long evolution in the methods of combat employment of naval forces. In the era of sail and 

until the late nineteenth century, the principal method of combat employment of 

the fleet to attain operational and sometimes strategic objectives was “decisive naval battle.” Some “decisive battles”—for example, Trafalgar in October 1805—led to 

drastic changes in the operational and sometimes even strategic situations. 

The methods of combat employment of naval forces gradually changed in the 

middle and late nineteenth century because of the effects of new technological advances. Great improvements in steam propulsion and the invention of the internal 

combustion engine made it possible to fit powerful plants on even small ships. 

The introduction of torpedoes and mines led to the design of new, small platforms 

capable of posing serious threats to larger ships. This, in turn, led to a proliferation 

of small warships of all types and classes. The numerical strength of the major navies steadily increased. In addition to battleships and cruisers, these fleets included 

a large number of smaller surface combatants, such as destroyers, torpedo craft, 

gunboats, and auxiliaries.2

The importance of a decisive battle became steadily less with the increase in 

size and corresponding changes in the composition of the major navies. Instead of 

comprising a single decisive battle to accomplish an operational and even strategic 

objective, war at sea between two strong opponents was fought over a large area 

and almost continuously. Numerous tactical actions were conducted by both large 

and smaller surface combatants. The deployment of forces became an integral part 

of a major clash between fleets. 

As early as the Russo-Japanese War of 1904–1905, war at sea was conducted 

almost continuously. It consisted of a series of major and minor naval actions all 

related in terms of purpose, place, and time. These actions took place over large 

parts of the Yellow Sea, the Sea of Japan, and even the Pacific Ocean.3

 In retrospect, 

the battle of Tsushima in May 1905 was the last “decisive” naval battle in history. 
This was not recognized by the theoreticians and practitioners of the day. Up to the 

beginning of World War I, all major navies planned to fight a “decisive battle” (also 

called “general fleet action”) aimed at obtaining command of the sea in a single 

clash of battle fleets. 

During World War I several large-scale fleet-versus-fleet actions took place in 

the North Sea, the Mediterranean, the Adriatic, the Baltic, and the Black Sea. Of 

these, the battle of Jutland, fought on 31 May–1 June 1916, came closest to what 

is known as a major naval operation. It comprised a series of small engagements 

and attacks aimed at an operational objective. The Germans’ plan was to bring the 

strength of the British Grand Fleet down to parity with their own High Seas Fleet.4

The British operational objective was the destruction of the High Seas Fleet. Both 

sides also conducted a series of actions aimed to provide combat support to their 

battle fleets.5

The first major naval operation in that war against an enemy coast was conducted by the Austro-Hungarian fleet, shortly after Italy’s decision to enter the war on 

the side of the Entente powers in May 1915. The main objective of that operation 

was to disrupt and significantly delay the movement and transport of mobilized 

Italian troops by rail along the Adriatic’s western coast. Another objective was to 

create fear and possibly panic among the Italians in the coastal area.6

During World War I, the first major joint naval operations emerged; the Entente’s amphibious landing at Gallipoli in April 1915 and the German landing on 

the Latvian coast in October 1917 (Operation ALBION) are the best-known examples. The principal objectives of the Gallipoli landing were to take Turkey out of the 

war, open a direct link with the Entente’s embattled Russian ally, force the Germans 

to shift troops from the Russian front, and influence Greece to side openly with 

the Entente powers.7 ALBION, conducted by the German navy and the army, was 

more successful. Its operational objective was to open the Gulf of Riga and thereby 

threaten the rear of the Russian 12th Army, defending the Baltic coast.8

World War I at sea proved that the fleets of the major opponents were too large 

and deployed too widely to be destroyed during a single battle or even a couple of 

them. It signaled the final demise of the decisive battle and the general fleet action 

and demonstrated that operational objectives in the theater could be accomplished 

only by a series of related naval battles and engagements, sequenced and synchronized in time and place—a major naval operation, in modern terms. Deployment, 

contact between opposing forces, pursuit, and withdrawal/redeployment were 

meshed to constitute a seamless whole. The entire naval operation was planned, 

prepared, and conducted by a single commander. It was based on a certain idea and 

a common plan.

In World War II, all the major navies conducted, independently and in cooperation with other armed services, a large number of major naval operations in all the 
xx MAJOR FLEET

VERSUSFLEET OPERATIONS IN THE PACIFIC WAR, 19411945 

maritime theaters. Among many major naval operations, a few stand out because of 

their importance to the course of the war. Major clashes of opposing carrier forces 

in the Pacific—notably the Japanese Port Moresby–Solomons operation (the battle 

of the Coral Sea, for the United States) in May 1942, the Midway-Aleutians operation (the battle of Midway), the A-Go operation (the battle of the Philippine Sea) in 

June 1942, and the Leyte operation in October 1944—were not truly “battles” but 

major naval operations. Several major naval operations were also conducted in the 

Atlantic during the long German struggle to cut off Allied maritime traffic and the 

Allied struggle to protect it. Examples are the German attempt cut off the Allied 

traffic in the northern Atlantic by employing the battleship Bismarck and a heavy 

cruiser in May 1941 (Operation RHEINUEBUNG, or Rhine Exercise) and the escape 

of the two German battle cruisers (Scharnhorst and Gneisenau) through the English 

Channel in February 1942 (Operation CERBERUS). The British carrier attack on the 

Italian naval base at Taranto in November 1940 (JUDGEMENT) and the Japanese 

attack on Pearl Harbor in December 1941 (HAWAII) were examples of major naval 

operations aimed to destroy a major part of an enemy fleet at its base. Also, several 

major naval operations were conducted by German U-boats against large Allied 

convoys in the northern Atlantic in the spring of 1943. The Allies conducted many 

major operations in the Mediterranean to defend their maritime traffic there; the 

best known are a major dual-convoy operation to Malta in June 1942 (Operation 

HARPOON/VIGOROUS) and a major convoy operation to Malta in August 1942 (PEDESTAL). At the same time, attacks on major Allied convoys were offensive major 

naval operations for the Axis forces. Major amphibious operations were conducted 

by all belligerents in several maritime theaters. For example, the Allied landings on 

Guadalcanal in August 1942 (WATCHTOWER), in the Gilberts in November 1943 

(GALVANIC), Sicily in July 1943 (HUSKY), and Salerno in September 1943 (AVALANCHE) were examples of such major naval/joint operations.

Since the end of World War II only a few major naval operations have been 

conducted. One reason is that most regional wars have not involved major navies 

on both sides. The amphibious landing by United Nations forces at Inchon in September 1950 (Operation CHROMITE), the blockade of North Korea’s coast during 

the Korean War (1950–53), and the British recapture of the Falklands in April–June 

1982 (CORPORATE) are examples of major naval operations in the postwar era.

In terms of its principal purpose, a major naval operation can be offensive or 

defensive. An offensive major naval operation is normally planned by the stronger 

side at sea, but one can be planned by the side on the defensive. Normally, the 

stronger side at sea would mount a single major naval operation or several in succession to obtain and then maintain sea control in a specific part of a maritime 

theater. Such operations can also be designed to reduce greatly or eliminate the 
threat posed by a numerically larger force, to facilitate operations in another part 

of the maritime theater. An offensive major naval operation can also be planned as 

part of a defensive campaign.

On the basis of the degree of participation of naval forces and other services, it 

is possible to differentiate major naval operations as naval, joint (multiservice), or 

combined (multinational). A major naval operation is conducted predominantly 

by the navy, although the air force or even ground forces can take part as well. A 

major naval/joint operation is planned and conducted by forces of the navy but 

with more substantial participation by one or more of the other services. In a maritime theater encompassing a large ocean or sea area, major naval operations would 

be conducted with the significant participation of the air force; ground forces may 

be involved as well. In contrast, major naval operations in littoral waters are likely 

to be conducted with the participation of all three services. All major amphibious 

landing operations are inherently joint, as are major operations against the enemy’s maritime trade, as well as the defense and protection of maritime trade in the 

littorals. 

In generic terms, the main purpose of a major naval/joint operation today in the 

case of a high-intensity conventional war at sea can be 

• Fleet versus fleet (aimed to destroy the enemy fleet at sea and/or in its 

bases) 

• Fleet versus shore (amphibious landing on the opposed shore or to destroy 

the enemy’s coastal installations/facilities) 

• Attack on the enemy’s maritime trade (including military shipping) 

• Defense and protection of friendly maritime trade (including military 

shipping) 

• Destruction of an enemy’s sea-based strategic nuclear forces or protection 

of one’s own, and support of friendly ground forces in offensive/defensive 

operations on the coast.

Major naval operations represent an area of study of operational art that Western naval theoreticians and planners have generally neglected. Too much emphasis 

is given instead to advanced technologies and tactics of weapons, at the expense 

of combined-arms tactics. The absence of an immediate and serious threat at sea 

today should not be allowed to prevent the development of sound naval theory and 

doctrine and the training of naval forces to prepare, plan, and execute major naval/

joint operations as part of land campaigns in the littorals or a maritime campaign. 

A major regional war with a strong opponent at sea may seem improbable, but in 

fact it is not unlikely. Experience shows that the major threats to national interests 

can emerge quickly and with little warning. Navies primarily exist, and are maintained, not to conduct operations short of war but to fight and win high-intensity, 

conventional wars at sea. 
xxii MAJOR FLEET

VERSUSFLEET OPERATIONS IN THE PACIFIC WAR, 19411945

NOTES 1 H. Engelmann, “Die Sicherstellung von Seeoperationen,” Militaerwesen 3 (March 1980), p. 69, and 

S. Filonov, “Morskaya Operatsiya,” Morskoy Sbornik

10 (October 1977), p. 24.

2 In 1900 the Royal Navy consisted of 205 warships: 

forty-five battleships, 126 cruisers, and thirty-four 

torpedo gunboats; the French navy had in service 

thirty-three battleships, thirty-eight cruisers, and 

twenty-one torpedo gunboats. Ronald B. St. John, 

“European Naval Expansion and Mahan, 1889–

1906,” Naval War College Review 23, no. 7 (March 

1971), p. 74.

3 Grundlagen der Theorie der operativen Kunst der 

SSK, ed. and trans. Adolf Feil (Dresden, Ger.: 

Military Academy Friedrich Engels, 13 March 1989; 

originally Operativnoye iskusstvo voenno-morskogo 

flota [Naval operational art]), p. 11. 

4 Elmer B. Potter and Chester W. Nimitz, eds., 

Seemacht. Eine Seekriegsgeschichte von der Antike bis 

zur Gegenwart, rev. ed. (Hersching, Ger.: Manfred 

Pawlak, 1986; originally Sea Power: A Naval History

[Englewood Cliffs, N.J.: Prentice Hall, 1960]), p. 358.

5 Grundlagen der Theorie der operativen Kunst der 

SSK, p. 11.

6 Potter and Nimitz, eds., Seemacht, p. 433.

7 James B. Agnew, “From Where Did Our Amphibious Doctrine Come?,” Marine Corps Gazette (August 1979), p. 53.

8 Ibid., p. 56; Carl O. Schuster, “Baltic Assault: Operation Albion,” Command Magazine (July–August 

1993), pp. 56–57; and Randolf Kugler, Das Landungswesen in Deutschland seit 1900 (Berlin: Oberbaum 

Verlag, 1989), p. 35.
I The Port Moresby–Solomons Operation and 

Allied Reaction, 27 April–11 May 1942

The ultimately unsuccessful Japanese attempt to capture Port Moresby in May 

1942 is commonly referred to as the “battle of the Coral Sea.” Almost all attention is usually focused on the decisive tactical engagement between the 

opposing carrier forces. However, the Japanese effort—formally code-named Operation MORESBY (MO) and often called the “Port Moresby–Solomons operation”

—was in formal terms a major offensive and joint operation, planned and executed 

to accomplish an operational objective, the capture of Port Moresby, on the Australian territory of New Guinea (now Papua New Guinea). For the Allies, in contrast, 

“the battle of the Coral Sea” was a major defensive and joint operation aimed at preventing an enemy landing at Port Moresby. Both U.S. and Australian naval forces 

and land-based aircraft took part. 

The Japanese inflicted larger losses on the Allies than they suffered and hence 

won a clear tactical victory; however, the Japanese failed to accomplish the ultimate 

objective of their operation, and hence the Allies won an operational victory. The 

operation was the first major setback for the Japanese in their drive, which had 

started with their surprise attack on Pearl Harbor on 7 December 1941, to expand 

their control in the Pacific. It is a powerful example of the value and importance of 

the human factor in warfare. More generally, and despite the passage of time, the 

Port Moresby–Solomons operation provides a number of operational lessons of 

great importance to current and future naval leaders.

The Strategic Setting

By the beginning of 1942, the strategic situation in the southwestern and South 

Pacific had become extremely serious for the Allies. The Japanese were on the verge 

of victory in the Philippines. They were making rapid progress in their invasion 

of the Netherlands East Indies (NEI) and thereby threatened northern Australia. 

The Japanese had included the invasion of the Bismarck Archipelago in their plan, 

developed in November 1941, for the “First Operational Stage” of the war in the 

Pacific. In their view, their major base at Truk, in the central Carolines, would not 

be secure as long as Rabaul, the capital of the Australian mandated territory, on 
J

New Britain, was in enemy hands.1 Accordingly, Japanese troops captured Rabaul 

on 23 January 1942. Its fall alarmed greatly the Australian government and people; 

Australia’s Northeast Area was now virtually unprotected. The Japanese next occupied the rest of New Britain, as well as the Admiralties, New Ireland, and Bougainville, in the upper Solomons. The vulnerability of Australia was shown also on 19 

February 1942 when four Japanese fleet carriers conducted a massive raid on the 

port of Darwin.2

By February 1942, the Japanese had accomplished all their initial strategic objectives, at far less cost than expected. However, instead of consolidating gains, the 

Japanese leaders made the fatal mistake of deciding to expand their defense perimeter. Japanese Imperial General Headquarters (IGHQ) in Tokyo had initiated staff 

studies for the Second Operational Stage of the war in January 1942.3

 The Plans Division of the First (Operational) Section of the Navy Section (i.e., the Naval General 

Staff) of IGHQ was a strong advocate of invading Australia. As early as December 

1941, the Naval General Staff had insisted on an invasion of strategically important points in northern and northeastern Australia; this could be accomplished, it 

was believed, with very little expenditure in men and materiel.4

 The Naval General 

Staff argued that Australia represented the greatest threat to Japanese control in 

the South Pacific, because it could serve as a base for a counteroffensive. Australia 

also possessed economic resources of great potential importance to Japan’s war industry.5

 The Naval General Staff argued that only three divisions, some forty-five 

to sixty thousand troops, would be sufficient to secure the flanks and center of 

Australia’s northeastern and northern coastline.6

In contrast, the Army General Staff was opposed to any invasion of Australia. The Army had in September 1941 only fifty-one divisions (twenty-eight divisions were deployed in China, thirteen in Manchukuo, and ten divisions, including 

five not fully trained, on the home islands). For the First Operational Stage, the 

army committed only eleven divisions (five from China and six from Japan) and 

achieved an enormous success in a very short period of time.7

 In contrast to the 

Naval General Staff, the army estimated that it would require at least ten, possibly 

twelve divisions, or 150,000 to 200,000 men, to invade Australia. To supply and 

sustain such a force would require 1.5 to two million tons of shipping. Such a huge 

requirement would in fact destroy the national economy.8

Gen. Hajime Sugiyama, chief of IGHQ’s Army Section (Army General Staff), 

was opposed to invasion of Australia.* He said, “If we take only part of Australia, it 

could lead to a war of attrition and escalate into total war.”9

 The Army General Staff 

intended instead to strengthen the defensive perimeter against the growing enemy 

force in Australia by capturing Port Moresby and important positions in the South 

* Throughout the book Japanese surnames are given last, in the Western fashion.
Pacific. The Japanese did not include Port Moresby as an objective in their plans 

for the First Operational Stage of war. In their view, to secure Rabaul, Port Moresby 

had to be seized; after the capture of Port Moresby, the enemy’s air strength in 

northeastern Australia would have to be neutralized.10 The army also considered 

the Solomons Archipelago to be a stepping-stone for an eventual enemy advance 

toward Japanese-held Rabaul—hence, the southernmost island of the Solomons, 

Guadalcanal, and the islands of Nauru and Ocean (modern Banaba) in the Gilberts 

had to be captured.11 The army requested the Imperial Japanese Navy (IJN) to support the Port Moresby–Solomons operation, and the commander in chief (CINC) 

of the Combined Fleet, Adm. Isoroku Yamamoto, reluctantly agreed. At the same 

time, Yamamoto believed that the Port Moresby operation would not present great 

difficulties.12

The Combined Fleet started planning for the Second Operational Stage of the 

war in January 1942. Yamamoto and his chief of staff, Rear Adm. Matome Ugaki, 

had views different from those of the Naval General Staff. Yamamoto insisted 

that the IJN had to retain the initiative, and he cautioned against complacency.13

He argued that the IJN should capture Midway and the islands of Johnston and 

Palmyra as advanced bases for an eventual landing on the Hawaiian Islands.14 He 

considered the idea of capturing New Caledonia, Fiji, and Samoa to be “folly.” 

Yamamoto believed that it would be difficult to hold them, some four thousand 

miles from the Japanese home islands. Moreover, the operation would not be effective, because as long as the U.S. Pacific Fleet was afloat, it could always reach Australia by another route. Yamamoto was willing to provide ships only for the capture 

of Port Moresby and Tulagi, in the Solomons, not for other objectives in the South 

Pacific.15 The Combined Fleet plan was to destroy the British Eastern Fleet and capture Ceylon (today’s Sri Lanka), thereby extending Japanese power over the central 

Indian Ocean, protecting the western flank of the NEI, and allowing the Combined 

Fleet to deal with the U.S. Pacific Fleet. 

On 29 January 1942, the Naval General Staff issued “Great Navy Instruction No. 

47”; the Army General Staff issued “Great Army Instruction No. 596” on 2 February. The Army-Navy Central Agreement stated that the “operational objectives” 

were to “invade key area in eastern British New Guinea and the Solomon Islands in 

order to blockade the communications lines between the Australian mainland and 

the region and in order to control the seas.”16 The “operational policy” to be pursued 

was that the army and the navy “will cooperate to invade the areas around Lae and 

Salamaua as soon as possible.” The navy “will seek an opportunity to independently 

invade Tulagi and establish a seaplane base on the island. The Army and the Navy 

will cooperate after the completion of the invasion of Lae and Salamaua to invade 

Port Moresby.” The navy would provide for the defense of the Lae, Salamaua, and 

Tulagi area, while the army’s responsibility would be defense of Port Moresby.17
J

The original idea of invading Australia was slowly abandoned by the Naval 

General Staff. Both general staffs agreed that the best way of isolating Australia was 

by capturing Fiji, Samoa, and New Caledonia. Sugiyama urged on Adm. Osami 

Nagano, chief of the Naval General Staff, the need for both services to study 

such an operation, dubbed FS. This option received a more favorable view in late 

February and the beginning of March 1942. On 28 February, a liaison conference 

concluded that total isolation of Australia was the key to Japan’s mastery of the 

southwestern Pacific.18

The Combined Fleet presented this plan to the Naval General Staff, which 

brought it to the attention of the army. The army supported eliminating the British fleet from the Indian Ocean and cooperating with the Germans in the Middle East but protested strongly the capture of Ceylon as premature. Army leaders 

were concerned that if they agreed that troops were available, the navy might 

divert their scarce resources for Pacific operations. Because of the army’s objections and the lack of response from Germany, IGHQ decided to limit operations 

in the Indian Ocean to massive raids by the First Air Fleet (the carrier striking 

force) against Ceylon and enemy shipping in the Bay of Bengal in early April. 

This operation would tie up five of the navy’s six large carriers until the end of 

the month. Then at least three carriers (Akagi, Sōryū, and Hiryū) would have to 

return to the homeland for upkeep and refitting; the First Air Fleet would not be 

ready to conduct another major operation until the end of May.19

The differences between the navy and the army regarding the objectives in 

the Second Operational Stage of the war were heatedly discussed during late 

January and February 1942. On 7 March, the services tried to resolve the dispute 

at the Imperial Liaison Conference in Tokyo. On 13 March an agreement was 

finally reached in a document entitled “Fundamental Outline of Recommendations for Future War Leadership.” In it the option of invading Australia was 

dropped.20

On this basis, in mid-March the Combined Fleet formulated a strategic plan 

for the Second Operational Stage of the war. The plan contemplated the capture 

of Midway Island in order to lure the U.S. Pacific Fleet into a “decisive battle.” 

From Yamamoto’s perspective, a great advantage of this plan was that it would 

require minimal participation by the army and so would not risk an army veto 

in IGHQ. The Combined Fleet plan was the subject of the discussion at a conference held at IGHQ on 2–3 April. At the conference the Naval General Staff 

insisted that the Midway operation include simultaneous capture of the western 

part of the Aleutian chain, and the Combined Fleet acquiesced. Naval General 

Staff also argued that the entire Midway operation should be delayed until late 

June, because it was unwilling to divert forces from the operation to secure Rabaul in support of operations in the Central and North Pacific. Yet on 5 April 
the Naval General Staff, faced with a threat by Yamamoto to resign, reluctantly 

agreed to his timetable for a Midway-Aleutians operation.21

In late April, IGHQ’s Army and Naval General Staffs agreed to a compromise 

plan that envisaged the occupation of strategic points in New Caledonia, the Fiji 

Islands, and Samoa, to be carried out sometime after the Port Moresby–Solomons 

operation.22 For its part, the Combined Fleet’s staff argued that any South Pacific 

project should be delayed until after the Midway-Aleutians operation.23 The Naval General Staff replied that preparations for operations in the “South Seas” had 

already started. It also maintained that Midway was beyond the effective range of 

Japanese land-based aircraft, that it would be very difficult to garrison and supply 

even if captured, and that its loss would not significantly affect American morale. 

In the Naval General Staff ’s view, cutting the supply lines to Australia would greatly 

affect morale; it would be more likely than a threat to Midway to draw the Pacific 

Fleet into a decisive battle and thereby shorten the war.24

The differences between the Combined Fleet and the Naval General Staff over 

the objectives and timetable of the Second Operational Stage of war were not resolved until after the Allied carrier raid on Tokyo—“the Doolittle Raid”—on 18 

April. This raid had (as its planners intended) a great and negative psychological 

effect on the Japanese strategic leadership. Both the navy and the army had failed 

in their duty to safeguard the homeland and the emperor from attack. Yamamoto 

regarded it as a “mortifying personal defeat.” The Japanese admirals and generals, 

suffering great loss of face, now overreacted and made several strategic decisions 

that proved fatal for Japan.25 Specifically, they adopted Yamamoto’s argument to 

extend the defense perimeter into the eastern part of the Central Pacific.26 A plan 

for the Second Operational Stage of war was approved by IJN Directive No. 86, 

which set the occupation of Port Moresby for early May 1942 (following raids in the 

Indian Ocean in April), that of Midway and the Aleutians for early June, and those 

of Fiji, Samoa, and New Caledonia for July.27

On the American side, strategy in the Pacific was largely driven by Adm. Ernest 

J. King, appointed as Commander in Chief, United States Fleet (COMINCH) on 

20 December 1941. On 16 March, President Franklin D. Roosevelt relieved Adm. 

Harold R. Stark as Chief of Naval Operations (CNO); ten days later, King assumed 

the duties of CNO in addition to those of COMINCH. Stark had been very pessimistic about the Allies’ ability to stem the tide of Japanese conquests. He had been 

willing to abandon all positions west of the international date line (longitude 180°

east), including the Philippines and Australia. In contrast, King was determined 

to oppose any further Japanese advance in the Pacific and eventually to mount 

a counteroffensive. Adm. Chester W. Nimitz, who had replaced Adm. Husband 

Kimmel as Commander in Chief, Pacific Fleet (CINCPac) on 31 December 1941, 

was directed by King to halt the Japanese advance, keep the line of communications 
J

with Australia open, and mount raids with carrier forces against the enemy’s strongpoints in the Pacific.28

Because of the growing Japanese threat to Australia, the British had suggested 

that the U.S. Pacific Fleet assume responsibility for defending the northeastern approaches to Australia and for securing Australia’s lines of communications with the 

United States. At first, the U.S. Navy had been reluctant to assume such responsibilities, the Pacific Fleet having been greatly weakened by the Japanese attack on 

Pearl Harbor. Yet King agreed on 1 January 1942 to study the problem. On 27 January 1942, the ANZAC (Australia–New Zealand Army Corps) Area was established. 

It encompassed eastern Australia, Tasmania, New Zealand, New Caledonia, the 

New Hebrides (modern Vanuatu), the Solomon Islands, Papua New Guinea, and 

Fiji. Australia and New Zealand would provide forces and would be supported by 

the United States. The combined force would be under command of an American 

flag officer and directly subordinate to the commander of the U.S. Pacific Fleet.29

King appointed Vice Adm. Herbert F. Leary as the ANZAC Area commander. 

Leary’s task was to cover the northeastern and eastern approaches to Australia and 

New Zealand, protect friendly shipping in the area, support the defense of island 

positions, and destroy enemy forces in the area.30

At the end of February of 1942, the Australian chiefs of staff assessed the country’s defense in light of the fall of Singapore, the raid on Darwin, and the impending Allied collapse in the NEI. They believed that if the Japanese advanced into the 

Coral Sea to cut off Australia’s communications with North America they might 

attack Port Moresby and then the Australian mainland. In their view, Port Moresby 

was too vulnerable to be reinforced but too important to be abandoned. Another 

option for the Japanese was to advance to the Solomon Islands and then capture the 

New Hebrides and New Caledonia.31

In the spring of 1942, the only troops available for defense of Australia were 

about 265,000 militiamen, poorly trained and equipped. The best Australian troops 

were deployed abroad—three divisions in the Middle East and elements of one 

division in Singapore, Timor, Ambon, and Rabaul.32 By mid-April, the Australian 

army at home had two first-line divisions, an armored division, and eight secondline militia divisions. The 41st Division was then the only major force of the U.S. 

Army in Australia.33

The key for the successful defense of Australia and New Zealand was the security of their sea routes to the U.S. west coast and Hawaii. If these lines were cut off, 

the defense of Australia and New Zealand would become almost impossible. This 

fact was also well understood by the Japanese planners.34 The United States had in 

October 1941 started construction of airfields in the South Pacific to provide an 

alternate air-ferry route to the Philippines. However, that work had not progressed 

far enough, and none of the islands was garrisoned. The responsibility for guarding 
the lines of communications in the South Pacific was in the hands of the U.S. Pacific Fleet and the Royal Navy. The U.S. Pacific Fleet was responsible for the defense 

of this line of communications east of longitude 180° east, on the basis of “ABC-1,” 

secret American, British, and Canadian military staff conversations (against the 

event of U.S. entry into war), and the U.S. Rainbow plans. The Royal Navy had the 

responsibility to defend the area to the west as far as longitude 155° east. The Pacific Fleet had additional responsibility to support the British in their area of responsibility, which included the east coast of Australia and the southeastern part of the 

Papuan Peninsula. This agreement became moot after the attack on Pearl Harbor.35

In the U.S. Joint Chiefs of Staff—the main arena for discussing strategic issues 

facing the United States—the Navy and Army had fundamentally different views 

on strategy in the Pacific. The U.S. Navy realized by February that the Philippines 

were lost. Hence, it believed, the defense of Australia and of communications to 

that country was of vital interest to the Allied cause. In contrast, the Army’s chief 

of staff, Gen. George C. Marshall, was adamant that the principal effort must be a 

cross-channel invasion of Europe. The main proponent of that view was Brig. Gen. 

Dwight D. Eisenhower, appointed as the War Department’s chief of War Plans Division on 16 February 1942. For Eisenhower the main conditions for winning the war 

were defense of the United Kingdom, continued participation of the Soviet Union in 

the war, and preservation of Allied positions in the Middle East and India to prevent 

the junction of German and Japanese forces.36 In Eisenhower’s view, the Japanese 

conquest of the NEI removed one of the major reasons for making a stand in the 

southwest Pacific. Because the Japanese now controlled the region’s oil and tin and 

practically the world’s entire rubber resources, the reasons for committing more 

forces in the theater had become “less compelling than they were three months 

ago.”37

King was persistent in his efforts to establish island bases with Army troops 

and land-based aircraft. He secured a small Army force to garrison Bora Bora in 

the French Society group. By early January 1942, the Army had promised to send 

troops to Canton and Christmas Islands in the Gilberts, thereby providing additional security to Samoa. It also promised to garrison New Caledonia. On 5 February, King recommended that Funafuti Atoll in the Ellice Islands (Tuvalu today) 

be made an advance base to cover Fiji and Samoa. He was concerned about the 

Japanese activity in the Gilberts and was convinced that the Allies had to interpose 

bases between them and southern Pacific islands.38

King fought battles with Marshall and Henry H. Arnold, commanding general 

of the U.S. Army Air Forces (AAF), in February and March 1942 over the allocation of scarce resources to the South Pacific. He selected Suva in Fiji and Tongatabu 

in the Tonga Islands as advance bases. Efate in the New Hebrides would be the 

first stepping-stone of a projected advance to the New Hebrides and the Solomons 
J

and on to Rabaul itself.39 On 15 February, he presented these ideas to Marshall. 

However, Marshall was not enthused, suspecting (correctly) that King was planning to mount a major offensive in the South Pacific, and that ran counter to his 

own Europe-first strategy.40

On 2 March, King sent a letter to the Joint Chiefs of Staff explaining his strategy 

for the southern Pacific. He argued for measures to secure the lines of communications between the United States and Australia and to establish a series of strongpoints for a gradual advance to the Bismarck Archipelago. This would divert Japanese forces from India and Australia. For the time being, he was willing to settle for 

garrisons only on Efate and Tongatabu. Yet he would not be content with the Allies’ 

remaining on the defensive in the Pacific for long.41

On 5 March, at a meeting of the Joint Chiefs of Staff with President Roosevelt, 

the main topic was Pacific strategy. Roosevelt seemed to agree with King’s views on 

the strategy to be followed in the Pacific. This in turn led King to direct Rear Adm. 

Richmond K. Turner, chief of the Navy’s War Plans Division, to develop a comprehensive plan for the war in the Pacific.42 On 16 March, King suffered a major 

setback: the Joint Chiefs decided to implement a War Department plan for rapid 

buildup in Europe, restricting reinforcements in the Pacific to “current commitments.” Nevertheless, the Joint Chiefs approved King’s request for bases at Efate 

and Tongatabu. The Army believed that three divisions in the southwestern Pacific were sufficient; the Joint Chiefs approved a single AAF pursuit squadron for 

Christmas Island, Canton, Tongatabu, and Efate. Fiji and New Caledonia would 

have two squadrons each of medium bombers, about sixty in all.43

Marshall and the Army realized the importance of keeping communications 

with Australia open but refused to allocate a significant number of aircraft or the 

best troops for the South Pacific. However, King decided to send one brigade of 

U.S. Marines to Samoa. This prompted the Army to provide small garrisons for 

Palmyra, Canton, and Christmas Island. The U.S. Navy established a fueling depot 

at Bora Bora. The importance of New Caledonia, which was also rich in minerals 

(nickel and chrome), finally convinced the Army to send what became known as 

the Americal Division (about fifteen thousand men) plus one AAF pursuit squadron to the island. The majority of these troops were drawn from poorly trained 

reservists, National Guardsmen, and fresh draftees.44

On 16 April, Turner presented his “Pacific War Campaign Plan” to King. The 

basic idea was that the Allies had to prevent the Japanese from occupying further 

territories; otherwise, the Allies would have much greater difficulty in mounting a 

counteroffensive and dislodging the Japanese from their more fortified positions. 

Turner’s plan contemplated a Pacific campaign of four phases. In the first phase, 

the United States would hold its current positions, including Port Moresby, and 
build up forces in the southern and southwestern Pacific. In the second phase, 

U.S.-Australian forces would mount a counteroffensive aimed at recapturing the 

Solomons, eastern New Guinea, and the Bismarck Archipelago. The third phase 

envisaged the capture of the Marshall and Caroline Archipelagoes, as well as the 

Marianas. In the final and fourth phase, the Allies would advance through the NEI 

or the Philippines, depending on which would provide greater strategic advantages. 

King approved Turner’s plan. It became the basic war strategy in the Pacific.45

King’s view on strategy in the Pacific proved to be the right response to the situation in spring 1942. Without a successful defense of Australia and of lines of communications in the South Pacific, an Allied counteroffensive would have been very 

difficult, if not impossible, to start in 1942, as was done. Marshall’s insistence on 

assigning the majority of forces and resources to preparation for the cross-channel 

invasion was the right strategy. Yet Marshall went too far in his refusal to assign 

larger and better trained and equipped troops to guard the remaining Allied outposts in the South Pacific. 

Operating Area 

The Port Moresby–Solomons operation was conducted over a large part of the 

southwestern Pacific (see map 1). The 1,850,000-square-mile Coral Sea is very 

deep (average depth about 7,850 feet); it is bounded in the west by northeastern 

Australia and the Great Barrier Reef, off the coast of Queensland; in the north 

by southeast New Guinea, the Louisiade Archipelago, the Solomon Islands, and 

the Santa Cruz Islands; and in the east by the New Hebrides and Loyalty island 

groups and New Caledonia. Its southern boundary runs along latitude 25° south. 

The distance from Cooktown to Espiritu Santo Island is about 1,300 miles, while 

Guadalcanal is about 950 miles away from latitude 25° south. Hence, the Coral Sea 

provided ample room for carrier operations. 

The Coral Sea is generally free of navigational hazards, except for numerous islands and reefs on the western, northern, and eastern fringes, and the Great Barrier 

Reef to the west. The Great Barrier Reef is composed of about 2,900 individual reefs 

and nine hundred islands. It stretches for over 1,600 miles from the Torres Strait 

and the Gulf of Papua in the north to an unnamed passage between Elliot Island 

and Fraser Island in the south. 

The Louisiade Archipelago is a barrier between the Solomon Sea in the north 

and the Coral Sea in the south. The Louisiades encompass an area of about 620 

square miles—10,040 square miles, if all outliers are included. It extends from west 

to east about 260 miles and sixty-five from north to south. The largest islands in 

the Archipelago are Rossel, Misima, Pana Tinani, and Vanatinai (Tagula). Other 

important islands are Deboyne, Renard, and Conflict. The only routes through the 

Louisiades to the Solomon Sea in the north are the (poorly charted in 1942) Jomard 
J

Southwest Pacific Area (SW

PA)

South Pacific Area (SO AC) P

145°E 150°E 155°E 160°E 165°E

15°S20°S

5°

10°

15°

20°

155° 160° 165°

00°S

Misima Deboyne

10°S

5°S

00°

150°

A U S T R A

L I A

Cooktown

Townsville

Rabaul

Tulagi

Choiseul 

Bougainville

Santa Isabel 

NewIreland

Guadalcanal 

Malaita

Rennell 

P

SanCristobal

 A C I 

F I C

O C E A N

0 100 200

Miles

New

Caledonia

Nouméa

Cape

York

Horn 

TORRES STRAIT

Charters Towers

Cloncurry

Kavieng

Gasmata

Madang

Lae

Salamaua

Buna

Port Moresby

N E W G U I N E A

GREEN Is 

QUEEN CAROLINE HARBOR Buka

Shortland 

Buin Kieta

Faisi 

Woodlark 

Samarai 

Rossel 

Tagula

RUSSELL

Is 

 SANTA CRUZ

GROUP

ST. JAMES BAY

Tontouta

LO

YALTY

Is

White Sand Point

MELE BAY Efate 

Espiritu

Santo 

SOLOMON ISLANDS GULF OF PAPUA

JOMARD PASSAGE

CHINA STRAIT

HUON GULF

S O L O M O N S E A

ADMIRALTY Is

B I S M A R C K S E A

BISMARCK

ARCHIPELAGO

Cape Nelson

ST. GEORGE’S

CHANNEL

LOUISIADE

ARCHIPELAGO

640 

Miles to 

TRUK

NEW

GEORGI

A

GROUP

145°

Manus

Finschafen

C O R A

L S E A

NEW HEBRIDES

Trobriand 

Cairns

New Brita ni

Map 1

Operating area
Passage, 4.9 nautical miles wide, and the four-mile-wide China Strait off the southeastern tip of New Guinea. 

In the northeast, the Coral Sea borders on the six-hundred-mile double and 

parallel chain of the Solomon Islands, stretching from the Bismarck Archipelago to 

the New Hebrides. The Solomons Archipelago consists of seven major islands having a total land area of about 14,600 square miles. In the eastern part of the Coral 

Sea, the largest group of islands is the New Hebrides. The largest reef is the Chesterfield Group, some 370 miles west of the northern tip of New Caledonia. Other 

reefs in the area are the Bellona Reefs and Observatory Cay. 

The most important current in the Coral Sea is the East Australian Current, 

sixty-two miles wide and 1,640 feet deep. It runs along the east coast of Australia 

to the cold waters of the Tasman Sea. It is strongest in February and weakest in August. The South Equatorial Current enters north of Espiritu Santo and divides into 

two branches; the Rossel Current passes northwest along the northern boundary of 

the Coral Sea, slows southwestward through the central part of the Coral Sea, and 

then runs southward along the coast of Australia.46

The weather in the Coral Sea is dominated by the semipermanent high-pressure 

area of the Southern Hemisphere. It generates southeast trade winds that dominate 

in all seasons between latitudes 20° and 25° south and west of longitude 155° east. 

The Coral Sea is occasionally subject to fronts moving off Australia, bringing towering cumulus clouds, showers, and squalls. The fronts gradually slow down and 

reach their northernmost limit near latitudes 8° and 12° south. The resulting bad 

weather may encompass an area fifty to 150 miles wide.47 In the Coral Sea, tropical 

cyclones are frequent occurrences, especially between January and April. 

Between September and December, the wind changes to northerly and northwesterly. Southwesterly winds prevail in May–August west of longitude 155° east. 

Gales are frequent between January and August. In January, a northwest monsoon 

may occur between latitudes 15° and 20° south and west of longitude 155° east. 

In those areas gales are rare except in June and August, when strong southeasterly 

winds occur for a few days per month. Southeasterly trade winds are strong north 

of latitude 15° south between March and November. Southeasterly trade winds 

would be advantageous to carriers moving southward, because such winds would 

facilitate the launching of aircraft. Hence, during the battle of Coral Sea the Japanese carriers—moving southward, into the prevailing wind—were able to launch 

their aircraft much faster than the Allied carriers, which had to turn away from the 

enemy carriers into the wind to launch and recover. On the other hand, the southeasterly wind gave the Allied carriers an advantage during their withdrawal from 

the operating area.48

The Japanese controlled a large number of positions in the central and southwestern Pacific prior to the Port Moresby–Solomons operation. The most important 
J

naval and air base in the central Carolines was the Truk (Chuuk today) Lagoon, 

forty-nine by thirty miles. Likewise, the newly acquired base at Rabaul, about 640 

miles south of Truk, was centrally located in the southwest Pacific. It had a firstclass anchorage. A 620-mile land-based-aviation patrol arc encompassed the Solomons to the east, most of eastern New Guinea to the west, and half of the Solomon 

Sea to the south.49

Other important positions captured by the Japanese in early 1942 were Manus 

Island, in the Admiralties; Gasmata, on New Britain; Kavieng, on New Ireland; 

Buka Island; Kieta and Buin, on Bougainville; Faisi Island; and Salamaua and Lae 

on New Guinea.50 The majority of these bases included airfields or seaplane facilities. Rabaul had two operational airfields (Lakunai and Vunakanau), used by both 

fighters and bombers; a third was under construction. Both Kavieng and Gasmata 

had airfields. Kieta had a landing strip, but it was not suitable for military aircraft. 

Faisi Island could serve as a seaplane base. Salamaua and Lae had airfields used 

by fighters and bombers.51 The anchorage at Shortland Island (seized by the Japanese on 13 March 1942), southeast of Bougainville, could shelter a large number 

of ships; an inlet at the eastern side of Shortland was suitable for a seaplane base.52

The area south of Rabaul contained many sheltered anchorages and numerous lagoons suitable for seaplane bases.

From the Allied perspective, the largest and the most important position was 

Port Moresby, on New Guinea. Port Moresby is separated from northeastern Australia by the 310-mile-wide Gulf of Papua and the ninety-mile-wide Torres Strait. 

It was excellently located to support air attacks against the eastern and southeastern coast of New Guinea and the Admiralties. Port Moresby was vulnerable to an 

assault landing. The 13,360-foot Owen Stanley Range provided a degree of security from attack over land.53 Control of Port Moresby would allow the Japanese to 

blockade the eastern sea approaches to Darwin and deny the Allies a forward base 

in New Guinea. It would also pose a threat of invasion against eastern Australia.54

Port Moresby lacked the good port facilities needed to serve as base when the 

Australian troops arrived in early 1941. However, within a year new facilities were 

built. Port Moresby remained virtually useless for Allied heavy bombers. The nearest supporting airfields were at Townsville, some seven hundred miles away in 

Australia.55 In the spring of 1942, Port Moresby was defended by several thousand 

poorly trained and equipped troops. The rest of New Guinea was defended by a local militia called the New Guinea Volunteer Reserve.56 

Naval/Air Bases

In spring 1942, the South Pacific lacked suitable bases, anchorages, and repair facilities for aircraft carriers and major surface combatants. The principal bases for 

the Allied ships were Tongatabu, in the Friendly Islands (Tonga); Nouméa, on New 

Caledonia; Efate, in the New Hebrides; Suva and Nandi, in Fiji; and Tutuila, in the 
American protectorate of Samoa. However, none was suitable for basing aircraft 

carriers.57 The nearest place usable for dry-docking aircraft carriers was Pearl Harbor, and for cruisers and destroyers, Sydney, Australia. Nouméa’s harbor could accommodate ships of any size. Its entrances were protected by mines, except for the 

Bulari Passage.58 Limited harbor facilities existed at Port Moresby; St. James Bay, on 

Espiritu Santo Island, in the New Hebrides; and Nouméa.59

Allied air forces used fields at Townsville, Charters Towers, Cloncurry, and Darwin in northeastern Australia. Horn Island, off Cape York in northern Australia, 

was an intermediate field for aircraft flying to and from Port Moresby. The airfields 

at Port Moresby were small, and they were used only for fighter aircraft and as staging points for bombers en route to the New Hebrides and the Solomons. They also 

lacked dispersal areas and hence were vulnerable to attack by the enemy fighters 

and bombers. Tulagi was a valuable base for searches by flying boats but was poorly 

defended and highly vulnerable.60 The Royal Australian Air Force (RAAF) operated 

a few PBY-5 Catalina flying boats from Gavutu Harbor on Tulagi until 2 May, when 

these aircraft were withdrawn. The Allies also started construction of an airfield at 

Le Tontouta, New Caledonia; another at Efate (Vanuatu today), a defended base for 

fighters and dive-bombers, was nearing completion.61 The anchorage at Nouméa 

was not suitable as a seaplane base, because it lacked antiaircraft defenses. Catalinas were also able to use anchorages at White Sand Point and Meli Bay, the New 

Hebrides.62

Theater Geometry

The Japanese base of operations anchored at Rabaul greatly facilitated the offensive employment of naval forces and land-based aircraft toward the Solomons, the Louisiades, and southeastern New Guinea. 

In spring 1942, the Allied base of operations in the South Pacific stretched 

in a generally westerly direction. It flanked the lines of communications 

from the U.S. west coast, Hawaii, and the Panama Canal to New Zealand 

and Australia but was unfavorable for preventing the Japanese from gaining 

control of additional strongpoints in the South Pacific. The distances separating the Allied bases from each other and enemy bases were overly long. 

For example, the sea distance from Nouméa to Tongatabu, Tonga, is about a 

thousand miles. New Caledonia and the New Hebrides are a similar distance 

from Australia’s coast. The distances from Samoa and Fiji to Rabaul are 2,230 

and 3,540 miles, respectively. Nouméa and Rabaul are separated by about 

1,385 miles of water. 

The base of operations for the Allied land-based aircraft in northeastern 

Australia was far from the newly acquired Japanese bases in the Bismarck Archipelago and the Solomons. For example, the air distances from Townsville 

and Cairns to Rabaul are 1,100 and 980 miles, respectively. Allied aircraft 
J

based in northeastern Australia operated along lengthy and converging lines 

of operation against targets off the eastern coast of Papua New Guinea. 

The Japanese naval forces and aircraft based at Rabaul operated along short 

and diverging lines of operation. For example, the sea distance from Rabaul to Lae 

is about 450 miles. Tulagi is about 550 miles by the sea southeast of Rabaul, while 

Deboyne Island is about 560 miles westward of Tulagi. Munda Point, New Georgia, 

is about 170 miles west-northwest of Tulagi and some four hundred miles southeast 

of Rabaul. The flying distance from Rabaul to Port Moresby is about five hundred 

miles. The sea distances from Rabaul to Brisbane and Nouméa are 1,435 and 1,385 

nautical miles, respectively. The sea distance from Rabaul to Port Moresby via the 

China Strait is 676 miles, 772 miles via the Jomard Passage, or 430 via the Grafton 

Passage (off the northeast coast of Queensland). The distance from Lae to Port 

Moresby via the China Strait is about 685 nautical miles. 

Allied carrier forces operating in the central part of the Coral Sea or south of the 

Solomons occupied a central position with respect to any Japanese force coming 

south from Rabaul or entering the Coral Sea from the east or west. They were able 

to use short and diverging lines of operation. 

The Japanese lines of communications within the Bismarck Archipelago and 

toward southeastern and eastern New Guinea were almost identical to their lines of 

operation. Their hub was Rabaul, and they were short and relatively easy to protect 

by land-based aircraft and ships. The route between the Bismarcks and the lower 

Solomons runs through deep water and is partially sheltered. 

In contrast, the Allied lines of communications to Australia and New Zealand 

were very long and highly vulnerable to the attacks by submarines. For example, 

the distances from the Panama Canal to Brisbane and Auckland are 7,765 and 

6,540 nautical miles, respectively. The distances from Honolulu to Papeete, Tahiti, 

and Suva, Fiji, are about 2,380 and 2,780 miles, respectively. Suva and Sydney are 

separated by 1,740 miles of water. From Cape Horn to Sydney the distance is 5,890 

miles. The sea distances from Nouméa to Brisbane and Auckland are 808 and 998 

miles, respectively. Melbourne is some 1,600 nautical miles, and Sydney about 

1,070, from Nouméa. The sea distance from San Francisco to Sydney is about 6,450 

miles. From the Panama Canal to Sydney the distance is about 7,680 miles.

Operational Command Structures 

The Japanese in the southern and southwestern Pacific lacked a single theater 

commander exercising command and control of all naval and ground forces. The 

Fourth Fleet was responsible for all operations in the South Pacific, the Caroline 

Islands, the Marshalls, the Marianas, and Palau.63 Its operational designation was 

“South Seas Fleet” (sometimes erroneously referred to as “South Seas Force”). Its 

commander was Vice Adm. Shigeyoshi Inoue, with headquarters in Truk; its secondary base was at Kwajalein, in the Marshalls.64 Inoue moved his headquarters 
temporarily to Rabaul for the pending Port Moresby–Solomons operation.65 On 5 

November 1941, the Fourth Fleet had become responsible for defense of islands in 

the South Pacific area and for patrolling and protecting shipping routes in the area. 

When war came, it was responsible for capturing Wake Island, and with the cooperation of the army, Guam; it was then, when opportunity occurred, to attack “strategic locations” in the Bismarck Archipelago.66 The organic forces of the Fourth 

Fleet consisted of the light cruiser Kashima (the flagship) and two cruiser divisions 

(CruDiv 18, with Tenryu and Tatsuta; and CruDiv 19, Okinoshima, Tokiwa, and

Tsugaru); Torpedo Squadron 6, with one light cruiser (Yubari) and three destroyer 

squadrons (DesRons 23, 29, 30); and submarine squadron (SubRon) 7, with one 

submarine tender (Jingei) and three submarine groups (SubGrus 21, 26, and 33).67

All Japanese naval land-based aircraft in the southwest and the South Pacific 

were subordinate to the Eleventh Air Fleet, under Vice Adm. Nishizō Tsukahara 

at Tinian, in the Marianas.68 The Eleventh Air Fleet consisted of the 21st, 24th, 

25th, and 26th Air Flotillas. It was responsible for securing eastern New Guinea, 

the Bismarck Archipelago, the Marshalls, Wake Island, the eastern Carolines, and 

the area around the Japanese homeland. It was also to cooperate with the Fourth 

and Fifth Fleets.69 The 24th and the 25th Air Flotillas were attached to the South 

Seas Fleet until control returned to the Eleventh Air Fleet on 17 April. The 24th 

Air Flotilla was redeployed out of the area, leaving only the 25th Air Flotilla to 

support the Fourth Fleet. The 25th Air Flotilla’s headquarters, under Rear Adm. 

Sadoyashi Yamada, was moved to Rabaul on 29 March and was activated on 1 

April. The 25th Air Flotilla was designated the 5th Air Attack Force (5th AAF) for 

operational purposes.70

In the spring of 1942, the Allied theater organization in the southern and the 

southwestern Pacific was divided between two theater-strategic commands (see 

map 2). The entire Pacific had been designated as an area of U.S. strategic responsibility. On 9 March 1942, the Allies formally divided the Pacific theater into three 

large “areas” (or in modern terms, theaters of war): the Southwest Pacific Area 

(SWPA), the Southeast Pacific Area, and the Pacific Ocean Areas (POA).71 Gen. 

Douglas MacArthur was appointed as the Commander, SWPA (COMSWPA); he 

formally assumed this responsibility on 18 April 1942. The ANZAC Area was formally abolished on 22 April, and to replace it Admiral Leary was appointed Commander, Allied Naval Forces. 

MacArthur was directed by the Joint Chiefs of Staff to accomplish the following 

objectives: 

a. Hold island positions between the United States and Southwest Pacific 

Area necessary for the security of lines of communications and for supporting naval, air, and amphibious operations against the Japanese. Hold 

key military regions of Australia as bases for future offensive action against 

Japan, and strive to check Japanese aggression in the SWPA.
J

C

A N

A D

A

U N I T E D S T

A T E S

U. S. S. R.

C H I N

A

I N D I

A

A U S T R

A L I A

Map 2: 

PACIFIC OCEAN AREA (P

O

A) AND I

TS ST

R

U

CTURE

FORMOSA

PHILIPPINE

IS.

GUAM

SOLOMON IS.

CANTON

SAMOA

FIJI

NEW ZEALAND

MID

WAY

HAWAIIAN IS.

J A P A N

NETHERLANDS INDIES

NEW GUINEA

NORTH 

PACIFIC ARE

A (NOR

PAC)

(JCS DIRECTIVE 

TO CINCPac)

(APPROVED B

Y PRESIDENT 30 MAR 1942)

CENTRA

L

PACIFIC ARE

A (CEN

PAC)

(JCS DIRECTIVE 

TO CINCPac)

(APPROVED B

Y PRESIDENT 30 MAR 1942)

Boundary moved to 18° 30’N, June 1944

SOUTH 

PACIFIC ARE

A (SO

PAC)

(JCS DIRECTIVE 

TO CINCPac)

(APPROVED B

Y PRESIDENT 30 MAR 1942)

(JCS DIRECTIVE TO SOUTHWESPAC)

(APPROVED BY PRESIDENT

30 MAR 1942)

(U.S. STR

ATEGIC DIRECTION)

(APPROVED B

Y PRESIDENT 30 MAR 1942)

PACIFIC THE

ATER

SOUTHEAST

PACIFIC AREA

(SE

PAC)

(U.S. N

AVY

DIRECTIVE

TO COMSE

PAC)

(APPROVED BY

PRESIDENT

30 MAR 1942)

P

A C I F I C O C E

A N

A R E

A S

SOUTHEAST ASIA

COMMAND

(COMBINED U.S.-U.K.

STR

ATEGIC DIRECTION)

SOUTHWEST

PACIFIC

AREA

INDIAN OCEAN AND

MIDDLE EAST

THE

ATER

(U.K. STR

ATEGIC DIRECTION)

0°

80°60°40°20°20°40°60°

160° 140° 120° 100° 80° 60° 180° 160° 140° 120° 100° 80°

Map 2

Structure of the POA
b. Support the operations of forces in the SWPA. Check the enemy advance 

across Australia and its essential lines of communications by the destruction of enemy combatant, troop, and supply ships, aircraft, and bases in 

eastern Malaysia and the New Guinea–Bismarck–Solomon Islands region.

c. Contain the Japanese forces within the Pacific theater. Exert economic 

pressure on the enemy by destroying vessels transporting raw materials 

from recently conquered territories to Japan.

d. Support the defense of the continent of North America. Maintain the Allied position in the Philippine Islands.

e. Protect the essential sea and air communications. Protect land, sea, and air 

communications within the SWPA and its close approaches.

f. Prepare for the execution of major amphibious operations against positions held by Japan, the initial offensives to be launched from the South 

Pacific Area and SWPA. Route shipping in the SWPA.

g. Support operations of friendly forces in the Pacific Ocean Area and in the 

Indian theater.

h. Prepare to take the offensive.72

On 3 April, the POA was subdivided into three (in modern terms) theaters of 

operations: the North Pacific Area (above latitude 42° north), the Central Pacific 

Area (from north latitude 42° to the equator), and the South Pacific Area (south 

of the equator and between the eastern boundary of the SWPA and longitude 110° 

west).73

Nimitz took officially the post of Commander in Chief, Pacific Ocean Areas 

(CINCPOA) in addition to that of CINCPac at 1100 on 8 May 1942, when the 

battle of the Coral Sea was almost over. Nimitz’s responsibilities as CINCPOA were 

as follows:

• Hold the island positions between the United States and the Southwest Pacific Area necessary for the security of the lines of communications between 

these regions; support naval, air, and amphibious operations against the 

Japanese forces

• Support the operations of the forces in the SWPA

• Contain the Japanese forces within the Pacific theater

• Support the defense of the continent of North America

• Protect the essential sea and air communications

• Prepare for execution of major amphibious offensives against positions held 

by Japan, the initial offensives to be launched from the South Pacific Area 

and SWPA.74

Nimitz was directed to appoint a commander for the South Pacific (SOPAC)

Area, who, “acting under his authority and general direction, would exercise command of the combined armed forces, which at any time might be assigned that 

area.”75 However, that post was not filled until 19 June 1942, when Vice Adm. Robert 
J

L. Ghormley assumed command of SOPAC. He initially established his headquarters at Auckland, New Zealand. 

Nimitz exercised command over all U.S. naval forces in the Pacific theater, including those in the Coral Sea, by virtue of his authority as CINCPac, but the Coral 

Sea itself was formally part of MacArthur’s SWPA. Nimitz and Rear Adm. Frank 

Jack Fletcher, Commander, Task Force 17 (CTF 17), had no control over supporting 

forces, such as Army Air Forces elements, which were provided by MacArthur. The 

resolution of this problem was that when American carriers and British or Australian forces operated in the same general area, the carrier task force commander 

would be in overall command. In all other cases, the senior commander, of any of 

the three nations, would be in command.76 The part of the SWPA in which combat 

actions took place during the battle of the Coral Sea was bounded by a line from 

longitude 130° east at the equator running eastward along the equator to longitude 

165° east, thence southward to latitude 10° south, and southwesterly to latitude 17°

south, longitude 160° east, and thence south.77 The SOPAC was bounded on the 

west by the SWPA and on the north by the equator. It encompassed New Zealand, 

New Caledonia, the Loyalty Islands, the New Hebrides and the Santa Cruz Islands, 

and the Solomons Archipelago.78 The separation line between SWPA and SOPAC 

caused problems during the battle of the Coral Sea because the Allied naval forces 

were subordinate to CINCPac but operated almost entirely within COMSWPA’s 

area of responsibility.

The Preliminaries

After the capture of Rabaul and other points in the Bismarck Archipelago, the Japanese moved quickly to expand their control in the southwest Pacific. On 29 January, IGHQ issued a directive to the CINC of the Combined Fleet that “the Army 

and Navy working together will occupy the Lae and Salamua sectors as quickly as 

possible. At the proper time the Navy will independently occupy Tulagi and secure 

a civilian seaplane base. If possible the Army and Navy will work jointly and occupy Port Moresby after the occupation of Lae and Salamua.”79 It also directed the 

Fourth Fleet on 2 February to attack and capture “strategic areas” in British New 

Guinea and the Solomons as soon as possible.80 The first operational objective was 

to seize the ports of Lae and Salamaua in the Huon Gulf, on the southeastern coast 

of New Guinea (the SR operation). On 13 February the Japanese navy and army 

signed an Army-Navy Local Agreement setting execution of the SR operation for 

25 February.81 On 16 February, Inoue and Maj. Gen. Tomitarō Horii, commander 

of the South Seas Force (or Detachment) agreed that the 2nd Battalion of the 144th 

Infantry Regiment, reinforced by one mountain artillery battery and other units, 

would attack Salamaua, while one battalion would capture Lae.82

In mid-February, Admiral King transferred temporarily Task Force (TF) 11, 

based on the carrier USS Lexington, to the ANZAC Area. Admiral Leary, together 
with CTF 11, Vice Adm. Wilson Brown, was planning to attack Rabaul. B-17 heavy 

bombers based at Townsville would strike Rabaul at the same time.83 On 20 February, TF 11 reached a point about 350 miles south of Rabaul, where Japanese landbased aircraft detected it. In the ensuing encounters the Japanese lost eighteen aircraft and the Americans only two;84 however, the element of surprise had been lost, 

and hence the carrier attack on Rabaul was abandoned.85 A major effect of this 

aborted raid was that Inoue decided to delay the SR operation until 8 March.86

On 4 March, the 24th Air Flotilla started raids on Port Moresby, Lae, and Bulolo 

(some thirty-seven miles southwest of Lae). The next day the Japanese convoy, escorted by the 6th Destroyer Squadron and the 6th and the 18th Cruiser Divisions, 

sortied from Rabaul bound for the Huon Gulf.87

Two days later, the convoy split into two groups, one to Lae and the other to 

Salamaua. On the night of 7–8 March, the Japanese landed, quickly captured both 

without opposition, and immediately started to build bases.88 By seizing control of 

the Huon Gulf the Japanese obtained control of the straits between northeast New 

Guinea and New Britain, as well as positions from which they could support further advances to the south.89

In early March, the Allies had TF 11 (with Lexington) and TF 17 (with Yorktown

and a screen of eight cruisers and fourteen destroyers) operating in the Coral Sea. 

The original plan was to conduct a moonlight air attack on Rabaul and Gasmata 

about three hours before sunrise. However, this plan was abandoned, because the 

majority of the Yorktown pilots were not qualified in night landings. The decision 

was then made to launch an attack at dawn on the enemy shipping and shore installations at Rabaul and Gasmata by cruisers and destroyers. If the enemy was alerted, 

the cruisers and destroyers would rejoin the task force without attacking.90 On 7 

March, Nimitz received information from Admiral Leary that an enemy convoy 

of one cruiser and several destroyers and transports had been sighted off Buna. 

The next day, Leary informed Nimitz that an enemy force of eleven warships, including four cruisers or destroyers, had started shelling Salamaua and Lae in the 

early morning and that a landing had followed. Searches conducted by the RAAF 

revealed that only three transports were at Rabaul and no shipping was at Gasmata. 

Yet on the previous day twenty-eight ships had been sighted at Rabaul.91

Nimitz reacted strongly and quickly to these reports and to reported movements of enemy forces toward the eastern coast of New Guinea. He directed both 

carrier groups to concentrate in the Gulf of Papua, from where they were to carry 

out attacks on the ships at Salamaua and Lae. The main reason for this decision 

was to surprise the enemy. A position eastward of Salamaua and Lae would not 

have ensured surprise, because these waters were patrolled by enemy ships; the 

Gulf of Papua offered more security from repeated attacks by aircraft at Rabaul and 
J

Gasmata. It also would allow a lower speed of approach and withdrawal, thereby 

preserving fuel. A major disadvantage of the attack from the Gulf of Papua, however, was that the carrier aircraft had to fly about a hundred miles over wild and 

poorly charted terrain and high mountain ranges often obscured by clouds.92

The plan also envisaged that a special group of four heavy cruisers and four 

destroyers under Rear Adm. John C. Crace, Royal Navy, would remain in the vicinity of Rossel Island (the easternmost island of the Louisiades) to cover carrier 

operations in the Gulf of Papua, intercept any enemy surface force striking at Port 

Moresby, and cover the arrival of Allied troops at New Caledonia.93

On 10 March, 104 Allied aircraft attacked Japanese shipping in the Huon Gulf 

from a position about fifty miles southwest of Port Moresby.94 The aircraft achieved 

complete surprise, approaching through the 7,500-foot pass over the Owen Stanley Range.95 Japanese sources cited their own losses as four transports sunk, three 

ships damaged moderately and three lightly, eleven fighter aircraft lost, and 130 

men killed and 245 wounded. Among the damaged ships were one seaplane tender, 

two light cruisers, and one destroyer.96 Allied postwar sources claimed much larger 

Japanese losses: thirteen out of eighteen transports sunk or damaged, of which several had to return to Japan for repairs.97 About four hundred Japanese were killed 

in the attack.98 The losses in shipping could not be replaced quickly. That was one 

reason that Inoue decided to postpone the Port Moresby–Solomons operation for 

one month; another reason was increased Allied air strength over New Guinea.99

On 16 March, Admiral Brown advised King, Nimitz, Leary, and Fletcher that 

in his view the Japanese air-early-warning system would not allow further surprise 

carrier raids like the one conducted against Rabaul on 20 February. Because of the 

350-mile gap between the Louisiades and Solomons, the cost of access to Rabaul 

from the south was increasingly more prohibitive.100

Allied and Japanese land-based aircraft conducted sporadic attacks on each 

other’s airfields starting in late January. The Allies raided Rabaul with small numbers of aircraft every other night from 24 January to 3 February. On 22 February, 

B-17s made their first attack on Rabaul. Allied attacks on Rabaul intensified in 

April. B-26 medium bombers struck on 9, 11, 12, 18, and 19 April. On the 11th and 

13th, an attack on Lae by a small number of medium bombers and fighters caused 

extensive damage, forcing the Japanese to move aircraft to Rabaul. After further 

raids on Rabaul on 22 and 23 April, Allied attacks there used only two to three 

medium bombers, leading the Japanese to believe erroneously that the enemy’s air 

strength at Port Moresby was greatly reduced. In fact, however, the Allies had reinforced Port Moresby, deploying additional P-39 fighters and basing B-25 bombers 

on Horn Island, off the York Peninsula.101

Japanese aircraft from Rabaul attacked Port Moresby for the first time on 3 February. On 14 March, nine Japanese land-based attack aircraft attacked Port Moresby. 
The same day the Japanese attacked Australia’s mainland for the first time, raiding 

Horn Island.102 The Japanese conducted extensive enemy air reconnaissance of Port 

Moresby, and on 18 March twin-engine planes bombed Tulagi and Gavutu. Port 

Moresby was attacked on 19 March by eight Japanese heavy bombers and on the 

next day by one heavy bomber and four fighters.103 On 21 March, the Japanese also 

conducted reconnaissance of the Allied bases at Townsville and Cooktown.104

On 11 April, the commander of the 25th Air Flotilla directed that the “operational policy,” of the 5th AAF, was to destroy enemy forces in northeast Australia, 

New Caledonia, and the Fiji area to prevent buildups in enemy air strength; to 

patrol the southern area of British New Guinea and the seas to the east, destroying 

mobile forces and disrupting supply lines; to cooperate with invasion operations; 

and to seek out and destroy the enemy fleet.105 The 25th Air Flotilla intensified its 

attacks on Port Moresby in early April, using bases at Rabaul and Lae. On 5–6 April 

the Japanese mounted large attacks on Port Moresby from Rabaul and Lae. Another 

raid was conducted on 7 April, and another on 10 April. The Japanese raids generally used only about half a dozen land-based attack aircraft and several fighters;106

for this reason, these attacks were not decisive.107

The Japanese attacks on Port Moresby were delayed by a week after 10 April 

because of the need to repair damaged aircraft. On 14 April, the number of serviceable aircraft in the entire 25th Air Flotilla did not exceed three fighters and three 

attack aircraft. The flotilla resumed full-scale raids on Port Moresby on 17 April, 

with fifteen fighters and seven attack aircraft, striking thereafter almost daily until 

the beginning of May.108 On 30 April, fourteen Japanese aircraft attacked the Allied 

airfield on Horn Island. Tulagi was bombed on 25 and 30 April.109

Japanese Information on the Enemy

The Japanese plans for the Port Moresby–Solomons operation were based on generally poor knowledge of the whereabouts and movements of enemy naval forces, 

the carriers in particular. This was a major reason for several decisions that were to 

cause major problems and setbacks for the Japanese in the course of the operation. 

Their main sources of information were visual observation by land-based search 

aircraft and submarines, interrogations of captured airmen, analysis of combat 

experience, and intercepts of plaintext messages. The Japanese, unable to decode 

Allied radio traffic, lacked direct knowledge of enemy plans and intentions, but 

their analysis of open sources, such as the Allied broadcasts and printed media, was 

generally good. 

The Japanese relied on land-based medium bombers, flying boats, floatplanes, 

and ship-based aircraft for sea reconnaissance. They rarely used carrier aircraft for 

scouting. The Japanese had fairly accurate information on the strength of enemy 

garrisons and air elements. For example, on 23 April the Fourth Fleet estimated 

correctly that Tulagi had a small garrison but that Port Moresby was defended by 
J

about five thousand troops. The Japanese assessed (again correctly) that Allied air 

strength in Australia had been increased, to probably two hundred first-line aircraft. They knew that the Allies had concentrated air strength in the Port Moresby, 

Port Darwin, and Townsville areas and that air activity in those areas was intense.110

However, the Japanese had very poor knowledge of the overall strength of enemy forces in the southern and southwestern Pacific. Their single greatest mistake 

was to assume, in the absence of information to the contrary, that “there [was] little 

probability of the existence of a powerful force in the area after the withdrawal 

of US task force.”111 Yet they also believed that it was “not unlikely that the enemy 

might conduct their own operations against our South Seas Fleet operational area 

east or south. The only U.S. carrier believed to be in the area is the Saratoga.”

112

These estimates were based on information from a Japanese picketboat that the 

Americans had employed three carriers in their raid on Tokyo on 18 April. However, from interrogations of captured pilots the Japanese learned that only two 

carriers (Enterprise and Hornet) had taken part. This meant, they assessed, that 

two others, Yorktown and Saratoga, were available. They erroneously believed that 

Lexington had been sunk by a Japanese submarine in January 1942. The Japanese 

did not know that Saratoga had sustained damage and was under repair. In any 

case, having observed no enemy carriers in the southern area since 10 March, the 

Japanese assumed that only one large carrier (Saratoga) would be operating there. 

They believed that the Royal Navy might have in Australian waters a battleship, two 

or three heavy cruisers, one light cruiser, and several destroyers. They also assumed 

that “even if enemy submarines are not particularly active, there is a strong chance 

that at least two or three” would operate in the area.113

Japanese Plans and Preparations

Operational planning in the Japanese army and navy was conducted by the respective general staffs and major field commands. The Army and Navy Sections 

were organized along similar lines. Operational plans were developed separately 

in the First Bureaus of the respective general staffs.114 However, there was a written law that the army had primary responsibility for strategic planning on Asia’s 

mainland and the navy in the Pacific; they shared these responsibilities in the 

southwest Pacific.115 Often, army-navy disagreement over specific joint operations 

led to delay or even cancellation. Even when an agreement was reached, the operation would normally be executed not by a joint commander but by respective service commanders. Unity of effort would be ensured by the terms of the pertinent 

Army-Navy Central Agreement.116 For joint operations planned by the numbered 

fleets, Army-Navy Local Agreements had to be signed to ensure unity of effort by 

both services. 

Inoue, of the Fourth Fleet, and his staff were primarily responsible for planning 

the employment of naval forces and Base Air Forces (i.e., naval land-based aircraft) 
in the southwest and South Pacific. Maj. Gen. Tomitaro Horii of his South Seas 

Force (or Detachment, a brigade-sized force) and his staff planned the employment 

of the army troops. The Fourth Fleet received on 29 January 1942 IGHQ’s great 

Naval Directive No. 47 directing the army and navy to cooperate in seizing Lae and 

Salamaua. Afterward, the navy, alone, would seize Tulagi and Guadalcanal. Both 

services would cooperate in seizing Port Moresby in early March. Afterward, New 

Caledonia, Fiji, and Samoa would be captured, thereby cutting off communications 

between the United States and Australia.117

IGHQ stipulated that Port Moresby and Tulagi should be seized immediately after Lae and Salamaua. That is, the Port Moresby–Solomons operation would be executed in March 1942, supported by land-based aircraft from Rabaul and seaplanes 

from bases to be constructed at Lae, Salamaua, and Finschafen.118 The original assumption that the enemy would have no carriers in the area became invalid in the 

light of the raids of February and March 1942. Also, enemy air strength in Australia 

was growing. In Inoue’s view the capture of Port Moresby and Tulagi would entail 

much more risk than initially envisaged and would need strong support by the 

large carriers. However, Yamamoto needed all five large carriers (Kaga had been 

damaged in a grounding in February 1942) and four battleships for raids against 

Ceylon and in the Bay of Bengal in early April (Operation C).119

Inoue sent a message to the Combined Fleet on 20 March arguing that considering the experience of the Lae-Salamaua operation, especially the appearance of the 

enemy carrier force, “it would be very difficult to assign protection for the transport convoy by land-based air units, and to protect the airbase establishment and 

the landing point after disembarkation.” He continued, “I would like to see discussion during a central agreement to doubly ensure the strengthening of land-based 

air units and the cooperation of a fully equipped aircraft carrier for the coming 

operation.”120

Final plans for the Port Moresby–Solomons operation were developed by the 

Fourth Fleet and its subordinate commanders during April 1942. The plans were 

considerably affected by Yamamoto’s decisions regarding the timeline of the MidwayAleutians operation and the availability of carriers. The Fourth Fleet also depended 

on the Combined Fleet for additional cruisers, destroyers, and land-based naval 

aircraft.

On 5 April Admiral Ugaki, Yamamoto’s chief of staff, circulated an outline of 

organizational changes based on IJN Directive No. 86. Among other things, the 

Port Moresby operation, to be code-named MO Operation, would take place in 

early May, prior to the Midway-Aleutians operation. From 20 April to 10 May the 

Combined Fleet would attach to the South Seas Fleet the large carrier Kaga, one 

seaplane tender, CruDiv 5 (Haguro and Myoko), CruDiv 6 (Aoba, Kinugasa, Kako, 

and Furutaka), and Destroyer Divisions 7 and 27.121 Inoue also learned that 24th 
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and 25th Air Flotillas would return to the direct control of the Eleventh Air Fleet 

commander, Admiral Tsukahara.122 In addition, the Combined Fleet attached the 

light carrier Shōhō from the 4th Air Flotilla to the Fourth Fleet; until then it had 

been used only for ferrying aircraft. Initially scheduled to take effect on 10 May, the 

command changes were later advanced to 20 April.123

On 5 April, Yamamoto directed Inoue that all plans for the Fourth Fleet had to 

be completed by 10 May. It was this change, combined with the advancement of 

the date for the execution of the Midway-Aleutians operation to early June, that 

had made it impossible to provide the frontline, large-carrier division Inoue had 

been promised in March. If the MO Operation had taken place in late May, Inoue 

would have been able to get two or more large carriers. Inoue had been a strong 

opponent of the Midway operation, because the Fourth Fleet would have to garrison and supply the island after its capture.124 He was now even more distressed 

that only one large carrier would be assigned to the MO Operation, and he asked 

the Combined Fleet to reconsider. Only three weeks earlier, he had been promised 

a carrier division of two large carriers. Inoue specifically requested that Carrier 

Division (CarDiv) 2 (Sōryū and Hiryū) be assigned to the operation, in addition 

to Kaga; CarDiv 2 was considered one of the most effective formations in the entire navy. Another problem with the schedule was that the 25th Air Flotilla would 

not have sufficient time to neutralize air opposition in the area prior to the start 

of the operation; its major components would not be ready for combat until 20 

April.125

The Combined Fleet’s staff duly reconsidered the question of carrier support 

for the MO Operation. Yamamoto, however, was reluctant to assign CarDiv 2 to 

the Fourth Fleet. That division, together with CarDiv 1, would be part of the pending Midway-Aleutians operation. Also, both carrier divisions needed refitting and 

training upon their return from the Indian Ocean. Yamamoto therefore decided 

on 10 April to allocate to the South Seas Fleet CarDiv 5, composed of the new carriers Shōkaku and Zuikaku, and two destroyer divisions. CarDiv 5 was the least 

experienced carrier unit in the Combined Fleet. This order became effective on 18 

April.126

On 17 April, Inoue directed CarDiv 5 to sail for Truk after a brief stay at Formosa. 

At that time, CruDiv 5 and six submarines of SubRon 8 assigned to the operation 

were in home waters. Inoue hoped to assemble at Truk and Rabaul the major part 

of the forces assigned to the operation in the third week of April.127

Not until 18 April did the Army General Staff provide specific instructions or 

exercise leadership concerning the pending operation. On that day, when the chief 

of the staff of the South Seas Force asked for instructions, IGHQ responded that 

the “Port Moresby offensive is essential for later operations, and should be carried 

out according to the commander’s judgment. This campaign is an opportunity to 
test army and navy cooperation for later operations, and should be executed by 10 

May at the latest.”128

Landing Options 

The Fourth Fleet’s planners considered three options for seizing Port Moresby: a 

land approach over the Owen Stanley Range, a barge “mobilization,” and a standard 

landing operation. Capturing Port Moresby by advancing over land was feasible if 

a road were built over difficult mountainous terrain. Some army commanders preferred this option to the risks of embarking troops on ships, which could be sunk.129

“Barge mobilization” meant landing troops in the southeastern part of New 

Guinea and transporting them on by self-propelled barges to successive points along 

the coast in the vicinity of Port Moresby. These landings would be conducted during the night to reduce the threat of air attack. The Japanese estimated that moving 

in darkness an average of sixty-eight miles each night, the barges would need about 

five days to reach Port Moresby. The problem was that the sea approaches to Port 

Moresby were navigationally very difficult, due to reefs and other obstacles; the 

barges would have to sail far from the shore. Barge mobilization would thus have 

been extremely difficult, but Inoue believed it feasible and in early April directed 

studies for transportation of food and munitions, embarkation rosters, cooking arrangements, etc.130 But in the end a standard landing was adopted, despite high 

risks for the convoy and covering forces; the strengthening of the Fourth Fleet had 

given its planners increased confidence in that option.131

The Japanese conducted extensive reconnaissance of the area of Port Moresby 

and the sea routes from Rabaul westward and southward. The army commander 

had asked the navy to obtain photographs of the landing area at Port Moresby and 

of the sea area between there and the island of Samarai, in the China Strait. Army 

officers accompanied reconnaissance flights over the landing area after 10 April.132

Yet after numerous reconnaissance and photographic flights, the Japanese acknowledged that they still lacked accurate information on facilities and enemy strength.133

As the Japanese usually did in preparing for amphibious landings, the 24th Air 

Flotilla in March conducted reconnaissance flights over the projected route to determine the best sites for seaplane bases; the 25th Air Flotilla did the same in midApril. Japanese search aircraft reconnoitered the islands of Gizo, Tetepare (in the 

central Solomons), Kiriwina, Normanby, Deboyne, Rossel, Samarai, and Abau, as 

well as Egum Atoll, Paria Reef, the Louisiades, Eagle Point, and Keppel Point for 

suitable places for seaplane bases. The Japanese surveyed waterways east of Australia, confirmed the accuracy of charts, reconnoitered the airfield on Horn Island, 

and photographed both landing sites at Port Moresby and potential barge routes 

from Samarai to Keppel Point.134 For some of these purposes the Japanese used 

short-range, single-float, reconnaissance biplanes that operated from shore bases 

established by tenders or from the tenders themselves. Submarine Division 33 at 
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Truk was directed to conduct extensive reconnaissance of the area to check the accuracy of charts.

On 16 April, Inoue convened a two-day staff meeting to discuss the plan and arrange final orders. Many subordinate commanders voiced strong misgivings. One 

major problem was the vulnerability of the MO Invasion Force along the southern 

coast of Papua New Guinea; enemy air bases were only about three hundred miles 

away. Within a circle of 275 miles from that area was a chain of numerous islands 

surrounded by reefs, severely restricting passage by ships.135

Sea Routes

The MO Invasion Force had three main routes available: the 670-mile-long westward route via the China Strait, a 950-mile route eastward around the Louisiades, 

and an 840-mile route southward through the Louisiades via the Jomard Passage 

and then across the Coral Sea to Port Moresby. The route through the China Strait 

was the shortest and ran mostly over deep water; it was also least exposed to air 

attacks. However, ships would have to sail in a single column. The eastward route 

was free of navigational obstacles but 110 miles longer than the southward route; 

it was also more exposed to attack by submarines. The southward route was less 

navigationally difficult than going westward and more secure than the eastward 

route; planners adopted it as a compromise.136

The plan was to organize a convoy of five ships from the army and six from 

the navy. The convoy, after departing from Rabaul, would run through St. George’s 

Channel and then south-southwest to west of Bougainville, turn southwest, and 

when eastward of Woodlark Island (Muyua today) head toward Deboyne Island 

and then enter the Coral Sea through the Jomard Passage, some 420 nautical miles 

south of Rabaul. Thereafter, and for the remainder of its advance to the objective, 

the convoy would be open to attack from enemy bases at Townsville and Cooktown. 

The planners calculated that if the Jomard Passage was navigated during the evening 

and a constant speed of eleven knots was maintained, the convoy would be exposed 

to attack in the Coral Sea for the next twelve hours.137 Hence, it was critical that the 

MO Carrier Force obtain local sea control in the Coral Sea. The basic idea for doing 

so was to send the MO Carrier Force sweeping around to the east of the Solomons 

(to avoid air searches), entering the Coral Sea from the southeast as the MO Main 

Force passed to the westward (see sidebar, “Japanese Order of Battle, May 1942”).138

Another problem was inadequate protection for the convoy from air attack. The 

navy believed that powerful carrier forces would compensate for the low speed of 

the convoy. However, General Horii was not convinced and expressed his fears on 

24 April to Rear Adm. Masao Kanazawa, commander of the Rabaul base detachment. In turn, Kanazawa contacted Inoue and suggested that a representative be 

sent to Rabaul to meet with Horii. On 25–26 April Horii and his staff met with 
Japanese Order of Battle, May 1942

CINC, Combined Fleet: Adm. Isoroku Yamamoto

Commander, Fourth Fleet (South Seas Fleet): Vice Adm. Shigeyoshi Inoue (Flagship CL 

Kashima, Rabaul)

Moresby (MO) Main Force

(Rear Adm. Aritomo Gotō, Commander, CruDiv 6)

CruDiv 6 (4 CAs—Aoba, Kako, Kinugasa, Furutaka)

DesDiv 7 (1 DD—Sazanami)

1 Light Carrier (Shōhō—12 A6M Zero fighters and 9 B5N Type 97 [Kate] torpedo bombers)

Tulagi Invasion Force

(Rear Adm. Kiyohide Shima, Commander, CruDiv 19)

CruDiv 19 (1 CM—Okinoshima, minus Tsugaru and Tokiwa)

DesDiv 23 (2 DDs—Kikuzuki, Yūzuki)

2 Transports (Azumasan Maru, Kōei Maru)

Minesweeper Flotilla 14 (Hagoromo Maru, Noshiro Maru No. 2)

2 Special Minesweepers (Wa No. 1, Wa No. 2)

SC Squadron 56 (Toshi Maru No. 3, Tama Maru No. 8)

Base Units (400 men of Kure 3rd Special Unit, part of the 7th Construction Bn., two 80 mm AA guns of 3rd 

Base Unit, one 130 mm MG of 3rd Base Unit, two 80 mm AA guns of 8th Base Unit)

Moresby (MO) Invasion Force

(Rear Adm. Sadamichi Kajioka, Commander, Torpedo Squadron 6)

Torpedo Squadron 6 (1 CL—Yubari)

DesDiv 29 (2 DDs—Oite, Asanagi) 

DesDiv 30 (3 DDs—Mutsuki, Mochizuki, Yayoi) 

DesDiv 23 (1 DD—Uzuki, minus Yūnagi, Kikuzuki, and Yūzuki)

1 Repair Ship (Ojima)

1 Special Minesweeper (Wa No. 20)

Transport Unit 

(Rear Adm. Kōsō Abe) 

1 CM (Tsugaru)

11 Transports: 5 navy (Mogamigawa Maru, Akihasan Maru, Chōwa Maru, Goyō Maru, Shōkai Maru), 6 army

(China Maru, Daifuku Maru, Asakayama Maru, Matsue Maru, Mito Maru, Nichibi Maru)

South Seas Force (5,000 men) 

Base Units (embarked; some 500 men of 3rd Kure Special Naval Landing Force, 10th Construction Section, 

four 120 mm AA guns and two 80 mm AA guns of 8th Base Unit, two 80 mm of 4th Base Unit, 

part of the Base Unit–Communication Personnel, Transportation Section)

Moresby (MO) Support Force (Covering Force)

(Rear Adm. Kuninori Marumo, Commander, CruDiv 18)

CruDiv 18 (2 CLs—Tenryu, Tatsuta)

2 AVs (Kiyokawa Maru, Kamikawa Maru)

Gunboat Division 5 (2 XAVPs—Nikkai Maru, Keijō Maru) 

1 Transport (Shōei Maru)

Minesweeper Flotilla 14 (Hagoromo Maru, Noshiro Maru No. 2)

Base Units (part of Kure 3rd Special Unit, part of the Communication Personnel of 8th Unit)

Moresby (MO) Carrier Force

(Vice Adm. Takeo Takagi, Commander, CruDiv 5)

CruDiv 5 (2 CAs—Myōkō, Haguro, minus Nachi)

CarDiv 5 (5th Air Flotilla), Rear Adm. Chūichi Hara, Commander (2 CVs—Zuikaku, Shōkaku)

(Shōkaku—21 A6M Zero fighters, 20 D3A Type 99 [Val] dive-bombers, 19 B5N Type 97 [Kate] 

torpedo bombers)

(Zuikaku—21 A6M Zero fighters, 21 D3A Type 99 [Val] dive-bombers, 20 B5N Type 97 [Kate] 

torpedo bombers)

DesDiv 27 (4 DDs—Shigure, Yūgure, Ariake, Shiratsuyu)

DesDiv 7 (1 DD—Shioakebono, minus Sazanami)

1 Fleet Tanker (Tōhō Maru)
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Capt. Iwao Kawai of the Fourth Fleet to discuss air protection of the convoy. Horii’s 

chief of staff suggested that the light carrier Shōhō from the Port Moresby Invasion 

Force be attached to CarDiv 5, thereby adding twenty aircraft to the force. Captain 

Kawai disagreed. The decision was made to keep Shōhō in direct escort of the convoy at all times. In the end, Horii and his staff were satisfied with that arrangement.

The Japanese planners also grappled with the problem of the barrier reef fronting Port Moresby. The reef is a natural fortress, running along the coast from the 

eastern tip of New Guinea to Port Moresby at a distance of from two to ten miles. 

Passage by landing craft was impeded at both low and high tides. Outside Port 

Moresby the large Sinavi and Nateara Reefs had to be penetrated, by one of three 

possible routes: the Liljeblad Passage, the Basilisk Passage, and the Padana Nafua. 

Vice Adm. Teruhisa Komatsu, Commander, Sixth Fleet

Advance Expeditionary Force

(Capt. Mitsunage Iwagama)

Eastern Detachment, SubRon 8 (Patrol/Scouting Group) (I-21, I-22, I-24, I-28, I-29, plus one) 

SubGru 21 (Raiding Force) (RO-33, RO-34)

Supply Force

2 Fleet Tankers (Ishirō, Hōyō Maru)

Bismarck Area (R) Defense Force

(Rear Adm. Masao Kanazawa, Commander, 8th Base Unit)

8th Signalss Unit

8th Submarine Base Force

81st Garrison Rabaul Unit

Gunboat Div 5 (Seikai Maru)

SC Div 56 (Kotobuki Maru No. 5)

MO Invasion Army Units

(Maj. Gen. Tomitarō Horii)

144th Infantry Regt.

1st Co., 55th Cavalry Regt.

1st Bn., 55th Mountain Engineer Regt.

2nd Co., 47th Mobile AA Bn.

6 Army Transports (part of the MO Invasion Force)

25th Air Flotilla (5th Air Attack Force)

(Rear Adm. Sadoyashi Yamada, Commander, 25th Air Flotilla)

1st Force (Tainan Air Group, at Rabaul, Lae) (18 Zero and 6 Type 96 fighters)

2nd Force (4th Air Group, at Rabaul, Lae) (17 Type 1 land-attack bombers)

3rd Force (Motoyama Air Group, at Rabaul) (26 Type 96 land-attack aircraft)

4th Force (Yokohama Air Group, at Tulagi, Shortland Island, Deboyne Island) 

(12 Mavis reconnaissance aircraft, 9 Zero Model 21 fighters)

Special Duty Force (1 AV—Mogamikawa Maru)

Nauru and Ocean Island Invasion Force

(Rear Adm. Kiyohide Shima, Commander, CruDiv 19)

CruDiv 19 (Okinoshima, Tsugaru, minus Tokiwa)

DesDiv 23 (2 DDs—Kikuzuki, Yūzuki)

2 Transports (Kinryū Maru, Takahata Maru)

6th Base Naval Landing Party

Kashima Naval Landing Party

1 CL (Tatsuta); 1 CM (Tsugaru) (after 11 May)

Sources: Bates et al., Battle of the Coral Sea, app. 1, p. 8; Bullard, trans., Japanese Army Operations in the South Pacific Area,

pp. 53, 56–57.
The Liljeblad Passage was within range of the Paga coast defense battery south of 

Port Moresby, the current there is swift, and sunken reefs lie in the passage and en 

route to harbor. This route, then, was unsuitable for a large landing force. The Basilisk Passage was a standard waterway but was in the direct line of fire from coastal 

batteries. The Padana Nafua route avoided these problems and was considered by 

the planners the most favorable.139

There was also the problem of sustaining troops once they landed. The Port 

Moresby area, poor in water resources, relied on rainwater; it was estimated that 

only four or five thousand troops could be stationed there.140 Supplies would have 

to reach a Japanese garrison by a long and vulnerable sea route either from Rabaul or the Huon Gulf, or by land over the fourteen-thousand-foot Owen Stanley 

Range. The ever-increasing enemy air strength in northern and eastern Australia 

would make it difficult for the Japanese to hold Port Moresby even if the landing 

were successful.

On 23 April, Inoue issued Order No. 13 as the basic directive for the MO Operation.141 It directed the South Seas Fleet and the South Seas Force to seize Port 

Moresby, important positions in southeastern New Guinea, and Tulagi Island in the 

lower Solomons; to establish air bases; and to intensify air operation around Australia. The services reconciled differences in a new Army-Navy Local Agreement 

on 25 April, and details were worked out by 3 May.142 On 28 April IGHQ issued 

directives for the execution of the operation. For the Japanese high command, the 

overall strategic objective remained isolation of Australia from the United States 

and other Allies. The long-deferred capture of Port Moresby and Tulagi would be 

followed by the occupation of important points in New Caledonia, Fiji, and Samoa. 

From these new bases, the Japanese aircraft and submarines would interrupt, if not 

cut off entirely, the flow of the troops and materiel to Australia and prevent it from 

becoming a base for a counteroffensive.143

On 28 April, Vice Adm. Takeo Takagi, commander of the MO Carrier Force, issued orders to his forces. As directed by Inoue, his plan included strikes against the 

bases in northeastern Australia. Rear Admiral Hara, commander of CarDiv 5, was 

very dissatisfied with the role assigned to his carriers. He was especially critical of 

the task of conducting strikes against northeastern Australia; in his view, it was too 

risky to operate carriers within the effective range of enemy land bases. Another 

problem was the presence of reefs and other navigational hazards, which would 

limit the maneuvering area for his carriers. Logistical sustainment under way was 

also inadequate; only a single fleet oiler was assigned to CarDiv 5 and its destroyers. On 29 April Inoue modified his order and left it to Takagi’s discretion whether 

to attack enemy air bases or not—Takagi was allowed to cancel the planned strikes 

if he failed to achieve surprise. However, on the same day Yamamoto directed Inoue to cancel all strikes on northeastern Australia. The MO Carrier Force was to 
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focus exclusively on the enemy carriers. Attacks on Australia’s mainland would be 

conducted by naval land-based aircraft. On 30 April, Inoue formally canceled the 

strikes, at the same time directing Takagi to have CarDiv 5 embark eighteen A6M 

Zero fighters for the 25th Air Flotilla and ferry them to Rabaul.144 The decision 

was made to ferry half of that force to Rabaul on 3 May and the remainder on the 

morning of 4 May.145

Inoue’s plan was extremely complex (see map 3). The planners sequenced the 

objectives and events with little consideration for potential difficulties due to long 

distances, poor radio communications, bad weather, and unforeseen events. The 

Fourth Fleet planners assumed that the enemy commander would be aware of the 

movements of the Port Moresby Invasion Force and would deploy a force into the 

Coral Sea to intercept it. The Japanese nevertheless took it for granted that they 

would achieve surprise. The most fateful mistake, which the Japanese would repeat 

on many occasions in the Pacific War, was to assume that the enemy would passively accept the Japanese narrative and react in a preordained way.146

General Horii, the South Seas Force’s commander, issued his orders for the operation on 29 April. They specified that the main forces would land at Taurama 

after passing through the Padana Nafua. Elements of the 1st Battalion of the 144th 

Infantry Regiment would pass through the Liljeblad Passage and land on the coast 

at Oiso. These landings would be completed by early dawn on 10 May. The Japanese also planned attacks on the enemy airfield north of Port Moresby.147

The commander of the 25th Air Flotilla, in his Operational Order No. 3, directed the 5th AAF to cooperate in intensified raids against northern Australia 

and Port Moresby after 1 May; patrol the route of the movement of the MO Carrier Force toward Port Moresby; patrol Tulagi and the route of the Tulagi Invasion 

Force; provide air protection for the convoy and over Port Moresby; and conduct 

reconnaissance of the landing sites. The 5th AAF, in turn, in Operational Order 

No. 2 updated its “operational policy.” Specifically, the entire force would “patrol 

the seas,” provide “speedy information concerning enemy naval activities,” and 

seek and destroy the enemy; conduct “repeated attacks and crush the enemy’s air 

strength” in New Guinea with the full strength of the 1st Force (Tainan Air Group) 

and 2nd Force (4th Air Group) prior to the start of the Port Moresby operation; 

patrol the skies over Rabaul and, in cooperation with the army, seek and destroy 

enemy aircraft; conduct reconnaissance over New Guinea and then over northern 

Australia; cooperate with the Port Moresby invasion; carry out various reconnaissance duties; provide air protection for the Port Moresby invasion convoy; attack 

and destroy enemy military installations in Port Moresby; and, after the enemy air 

strength in the Port Moresby area was destroyed, “seek out and destroy powerful air 

units in northeast Australia.” The patrol plan of the 25th Air Flotilla for the operation envisaged eight patrol sectors (A through I), originating at Lae (sector A); at 
145°E 150°E 155°E 160°E 165°E 5°S 10°S 15°S 20°S 5° 10° 15° 20° 145° 155° 160° 165° 00°S 150° 00° TRUK

A U S T R A

L I A

Cooktown

Townsville

Rabaul

Tulagi

Choiseul

Bougainville 

Santa Isabel

NewIreland

Guadalcanal 

Malaita

Rennell 

SanCristobal 

0 100 200

Miles

New

Caledonia

Nouméa

Cape

York

Horn 

TORRES STRAIT

Charters Towers

Cloncurry

Kavieng

Madang

Lae

Salamaua

Port Moresby

N E W G U I N E A

GREEN Is 

QUEEN

 CAROLINE HARBOR

Buka

Buin

Shortland 

Samarai 

Rossel 

RUSSELL

Is

SANTA CRUZ

Is

Tontouta

LO

YALTY

Is

Efate 

Espiritu

Santo 

GULF OF

PAPUA

JOMARD PASSAGE

CHINA STRAIT

HUON GULF

BISMARCK

ARCHIPELAGO

Cape Nelson

Deboyne 

1

4

X+5

Air Strikes Formally

Canceled on

30 April

Misima

X–5 

X+2

MO CARRIER FORCEMO IN

VASION FORCE

TULAGI IN

VASION FORCE

MO MAIN FORCEMO SUPPORT FORCENAURU & OCEAN ISLANDIN

VASION FORCE

10 M

AY 1942

SUBMARINESEAPLANE BASE

LEGEND

X-D

AY

X+2

X–4/X–3

X–6

1

2

5 AAF

RECEIVES FIGHTERS

X–4

X–5

Ferrying18 Zeros

X–8

X–11

X–6

Nauru &

Ocean

Island

X+0

New Brita ni

Map 3

Japanese operational idea 

(scheme)
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Rabaul (sectors B and C); at Shortland Island (sectors D and E); at Tulagi (sectors F 

and G); and at Deboyne Island (sector I)—all out to 680 miles.148

Task Organization

Normally in Japanese joint operations, unity of command was rare. Separated 

command for army and naval units was the general practice. However, the Japanese made an exception for the Port Moresby–Solomons operation. Inoue exercised full command and control over all navy and army forces in the operation. 

Rear Adm. Aritomo Gotō was in command of all the invasion forces, and Major 

General Horii was in command of the army units assigned for the occupation of 

Port Moresby.149

Operational Design

The capture of Port Moresby was the principal and ultimate objective of the entire 

operation. It was an operational objective, in terms of its scale. The Japanese believed that by controlling Port Moresby they would deny the enemy a major air base 

within effective range of Rabaul. From Port Moresby the Japanese could dominate 

the whole of New Guinea and threaten northern Australia.150 Port Moresby would 

be valuable as a springboard for the subsequent Japanese operations against New 

Caledonia, Fiji, and Samoa. It would also help secure Lae and Salamaua ports from 

air attacks. For its part, the Combined Fleet believed that the MO Operation could 

induce the U.S. Pacific Fleet to respond, thereby setting a trap for its destruction.151

However, there was a serious mismatch between ends and means. Even if successful 

in this operation, the Japanese clearly lacked sufficient air strength to counter the 

growing Allied air capabilities in northeastern Australia. Enemy aircraft would be 

still able to attack Japanese forces in the western Coral Sea.152

The capture of Tulagi was a supporting and major tactical objective. A seaplane 

base there would protect the left flank of Japanese forces moving to seize Port 

Moresby. It would allow the Japanese to extend their search coverage farther eastward. Also, the Japanese believed, a seaplane base at Tulagi would make it difficult 

for the enemy to conduct reconnaissance from Nouméa and Port Moresby to track 

Japanese movements.153 The Japanese, in contrast, would be able to search east of 

the Solomons and over the eastern Coral Sea. The plan also envisaged the capture of 

Samarai Island, a mile and a half across, as the key to control of the China Strait.154

The Japanese made a major error in trying to capture Tulagi and Deboyne Island 

(where a seaplane base would be established) in the course of the MO Operation; 

it might have been better to do so beforehand, making the MO Operation itself 

simpler and more executable. However, the single greatest error in the designing 

of the Port Moresby–Solomons operation was failure to obtain local control in the 

Coral Sea. This should have been the initial and the principal supporting objective 

of the entire operation. The main prerequisite of success was the destruction or 

serious weakening of the enemy’s operational center of gravity, his carrier force; 
only after that was accomplished would the other objectives have been achievable. 

Instead, the Japanese believed that all force elements could be deployed and sent to 

the objective area almost simultaneously. 

In addition, the plan for logistical sustainment of naval forces was inadequate, 

because of the lack of the fleet oilers capable of underway refueling.155 The supply 

group consisted of only two fleet oilers (some sources say three). Only one was assigned to the MO Carrier Force. This greatly increased the time required for the 

carriers to refuel at sea and thereby made them more vulnerable to submarine and 

air attack.

Although the Port Moresby–Solomons operation had unity of command to a 

degree unusual for a Japanese operation in the Pacific War, the majority of naval 

units did not belong organically to the Fourth Fleet. The navy’s land-based aircraft 

were subordinate to Admiral Tsukahara, commander of the Eleventh Air Fleet, 

and the submarines were under the control of Vice Adm. Teruhisa Komatsu, commander of the Sixth Fleet. CarDiv 5 and CruDiv 5 were temporarily under Inoue’s 

command; by the end of May 1942 they were to return to their organic forces.156

Vice Admiral Takagi was the commander of the MO Carrier Force. However, because he had little experience in air operations, Rear Adm. Chūichi Hara was in 

tactical command of CarDiv 5.157

Operational Idea. The Japanese operational idea (scheme) for the Port Moresby–

Solomons operation was very complex. The invasion force was divided into nearly 

a dozen smaller force elements, fragmenting and greatly weakening its overall 

strength. Inoue and his planners divided available seagoing forces into nine elements for the Port Moresby–Solomons operation and one for the separate Nauru–

Ocean Island operation. A short timeline meant that several force elements had to 

be assigned multiple tasks.158 The operational idea was intended to ensure speed in 

action—almost all forces taking part in the operation would converge toward the 

exit from the Louisiades. The outcome of the entire operation hinged on achieving surprise. Yet the planners did not develop any deception plan to enhance the 

chances of doing so. The basic idea was to envelop the enemy carrier force, with the 

MO Carrier Force sweeping around to the east of the Solomons and then entering 

the Coral Sea from the southeast, and the MO Main Force coming from the northeast to the area west of the Solomon Islands.159

The MO Operation was to be completed within twelve days, from the first force 

deployment to the landing at Port Moresby. No flexibility was incorporated to provide for delays due to unforeseen events or enemy action. Specifically, the landing at Port Moresby would take place on 10 May (X-day). Tulagi would have been 

captured on X–7 (3 May). A seaplane base would be established at Tulagi on X–6 

(4 May), on Deboyne Island on X–4 (6 May), and on Samarai on X+2 (12 May). 
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Naval construction troops would repair the airfields and receive the fighters of the 

5th AAF at Lae on X+2 (12 May). The Nauru-Ocean Invasion Force, sailing out of 

Kavieng, would seize these two islands on X+5 (15 May).160

The initial task of the MO Main Force was to provide distant cover for the Tulagi landing and then antiaircraft (AA) defense of the MO Invasion Force.161 Inoue 

wanted the light carrier Shōhō to be part of the MO Carrier Force. However, as 

noted above, at the insistence of General Horii Shōhō was assigned to the MO Main 

Force.162 The Japanese apparently believed the Allies would react strongly to the 

capture of Tulagi and that the MO Main Force should be positioned some 150 miles 

west of Tulagi so as to cover either Tulagi or the MO Invasion Force. However, 

Gotō’s force was not strong enough to defend either force against determined attack 

by enemy carriers.163 The MO Support Force (also called the Moresby Escort Fleet) 

was to support both the Tulagi and Port Moresby landings.164 On X–5 (5 May), 

the Support Force would reach Deboyne Island to construct a seaplane base from 

which floatplanes would search to the south and cover the convoy as it transited 

through the Jomard Passage on X–5/X–4 (5/6 May). On X+2 (12 May) it would 

establish at Samarai Island a seaplane/supply base to protect the supply line to Port 

Moresby.165

The Zuikaku and Shōkaku carrier groups were organized as a single force, thereby greatly increasing their offensive capabilities.166 The principal tasks of the MO 

Carrier Force were to provide distant cover and protection to the MO Invasion 

Force and to destroy the enemy fleet if it appeared.167 On the way, it was to pass 

within 350 miles of Rabaul to ferry eighteen Zero fighters there on X–8 (2 May).168

It would then sail east of the Solomons, providing direct support to the Tulagi Invasion Force, and then on X–5 (one day after the flying boats started to use the Tulagi 

base) enter the Coral Sea to support the MO Invasion Force as required. If a strong 

enemy force were detected, the MO Carrier Force would attack and destroy it; otherwise, it would prepare for a decisive encounter while protecting the MO Invasion 

Force. After the landing at Port Moresby, the MO Carrier Force would remain five 

more days in the area to counter any powerful enemy naval force that appeared in 

the Coral Sea. Afterward, it would provide direct support to forces taking part in 

the invasions of Nauru and Ocean Island.169

The Advance Expeditionary Force (Submarines) would destroy the enemy striking forces in the Coral Sea, destroy enemy shipping, and conduct reconnaissance.170

Most submarines that took part in the Port Moresby–Solomons operation belonged 

to the Eastern Detachment of SubRon 8. These submarines were planned to leave 

for Truk in mid-April.171 The task of SubRon 8 was “to prepare for the enemy fleet, 

deploy, and wait for the enemy.”172 On X–5, four submarines from SubRon 8 would 

establish a scouting line about 285 miles southwest of Guadalcanal to intercept any 

enemy force passing from Brisbane and Sydney toward Tulagi. Also, one submarine 
would patrol off the eastern Australian coast and another near Nouméa.173 The two 

submarines of SubGru 21 (the Raiding Force) would reconnoiter the approaches 

to Port Moresby, attack enemy ships, and guide the invasion convoy to the outer 

harbor.174 However, the submarine force was numerically too weak to reconnoiter 

so large an area as the Coral Sea.175

Deployment. Though execution of the operation was to be almost simultaneous, 

the actual departures of the forces taking part were staggered; basing areas were 

widely separated, distances to the objective areas were long, and speeds of advance 

varied greatly. The Tulagi Invasion Force and the MO Support Force would sail on 

29 April from Rabaul and Truk, respectively. The MO Main Force would leave Truk 

on 30 April, and the MO Carrier Force would sortie from Truk the next day. The 

MO Invasion Force would sail from Rabaul on 4 May.176

Information Available to the Allies

Communications intelligence (COMINT) was the U.S. Navy’s principal source of 

intelligence on the IJN at the beginning of the war in the Pacific. The Japanese 

radio messages were at that point intercepted by stations in Hawaii, in the Philippines, on Guam, and on Bainbridge Island (in the state of Washington), as well 

as by a network of direction-finding stations. Two categories of intelligence were 

used: decryption intelligence (DI) was that derived from the text of a message, 

while traffic intelligence (TI) was obtained from a message’s externals, such as its 

originator or addressees. Both DI and TI played major roles in the battle of the 

Coral Sea, and Midway as well.177

By the spring of 1942, three centers were analyzing Japanese radio traffic, all 

regularly exchanging data to assist each other in traffic analysis, call-sign recovery, 

and decryption. In Washington, D.C., was Section G, the Communication Security 

Section (code name NEGAT) of the Office of Naval Communications. The other 

two stations serving the Allied commanders in the Pacific were Fleet Radio Unit 

Pacific (FRUPAC, also known as the station HYPO) at Pearl Harbor and CAST at 

Cavite and later on Corregidor in the Philippines. In April 1942, CAST personnel 

was moved to the newly established inter-Allied signal station, Fleet Radio Unit 

Melbourne (FRUMEL). (FRUMEL was often referred to as BELCONNEN, after 

the Australian Belconnen Naval Transmitting Station, near Ginninderra Creek, 

northwest of Canberra.)178 FRUMEL was subordinate to SWPA command. On the 

CNO staff (known as OpNav), the Navy Radio Intelligence Section, Op-20G, was 

responsible for integrating all COMINT on the IJN.179

The version of the Japanese cryptographic system, Naval Codebook D, used at 

the beginning of war was known to the Americans as JN-25B. Just prior to the war 

the Japanese implemented a random additive table that greatly concerned American cryptanalysts until in February 1942 they concluded that it did not constitute a 
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completely new codebook. HYPO concentrated on JN-25B, in concert with CAST 

(then on Corregidor). NEGAT reinforced the efforts on JN-25B and monitored the 

Japanese diplomatic code, known as “Magic.” The three stations exchanged data 

and reviewed findings through a radio network known as COPEK.180

About half the high-level communications in the IJN used JN-25. This codebook consisted of a printed list of thirty thousand five-digit numbers, each of which 

stood for a unit designation, a technical term, a verb, and so on. Separate ciphers 

for dates, grid locations, and geographic places also appeared within the messages. 

Before transmission of a message, a series of five-digit numbers taken from a list of 

up to fifty thousand random groups was an enhancement to the cipher. The system 

was primitive in comparison to electrical cipher machines then in use, such as the 

U.S. ECM (Sigaba) and the German Enigma. Nevertheless, the Japanese code system itself was formidable.181

In the spring of 1942 American naval cryptanalysts could not read all, or even 

most of, the messages sent in the JN-25 system. Nor could they analyze more than 

a fraction of the many thousands of communications transmitted by the IJN in 

any one day. What they were mostly able to do was recognize associations, linking 

specific units on the basis of the appearance together of their call signs. Although 

they had deduced the meanings of some code groups, they could rarely read more 

than 10 to 15 percent of the text. By April, the cryptanalysts were deciphering more 

and more of what they analyzed. The Japanese had used the JN-25B version for 

many months, giving the cryptanalysts more time than usual to work on it. The IJN 

planned to issue a new Naval Codebook D edition in April 1942. However, delays 

in distribution postponed the changeover first to 1 May and eventually to 27 May.182 

Had the Japanese gone over to the new edition as originally scheduled, American 

cryptanalysts would have been in the dark for many weeks at a critical time. 

The most revealing indicators of Japanese future intentions were the digraphs 

and trigraphs used as designators throughout the IJN. They represented specific 

places, throughout the Pacific, and often conveyed organizational information. For 

example, digraphs beginning with A applied to American targets in the Central and 

North Pacific. Australian targets in the Papua/Solomons area were given the initial 

letter R, and groups beginning with D designated British/Australian targets in the 

Indian Ocean. COMINT analysis used that system to identify Japanese targets.183

COMINT remained the single most valuable source of accurate and timely information on enemy intentions for Admirals King and Nimitz and the major naval 

commanders in the Pacific. This information was especially critical early in the 

war, when the Allies were numerically inferior to the Japanese. Timely information 

on where the Japanese carrier forces were allowed Nimitz and King to employ their 

own carrier forces for raiding newly acquired Japanese positions.184 Such knowledge 

would soon allow prompt deployment of carrier groups to thwart major Japanese 
thrusts, notably, as will be seen, in the Coral Sea and at Midway. MacArthur relied 

less on COMINT than did Nimitz and King and far more on visual reconnaissance, 

such as aerial scouting and that from coast watchers.185

In the first two weeks of March 1942, a daily CINCPac Combat Intelligence Bulletin, based on COMINT supplied mainly from Hawaii but with occasional contributions from Corregidor, were sent as messages to all task force commanders. The 

series was replaced on 17 March by the CINCPac Intelligence Bulletin, also based 

on communications intelligence, with contributions from Melbourne. After midMarch the COMINT centers sent bulletins to CINCPac, usually based on translations that originated each day in HYPO. A Commander, 14th Naval District (COM 

14) Radio Digest was usually sent onward by CINCPac almost verbatim, as well as 

the COM 14 COMINT summary.186 Intelligence officers and cryptanalysts worked 

together to evaluate the texts of decrypted messages; the intelligence officers of 

the various commands then combined radio intelligence with combat intelligence 

information to produce balanced estimates. 

The most important center for this work in the Pacific was CINCPac Fleet 

Intelligence, under Lt. Cdr. Edwin T. Layton.187 Layton supplied information on 

enemy forces and possible intentions for use by CINCPac’s War Plans Section in 

its situation estimates. Each day he composed a summary of pertinent intelligence 

data, the CINCPAC Intelligence Bulletin, and sent it by radio to COMINCH, OpNav, all CINCPac task force commanders, the Australian and New Zealand naval 

boards, Admiral Leary’s SWPA naval forces, the commander of the British Eastern Fleet in the Indian Ocean, and the U.S. Special Liaison Officer stationed in 

London for cooperation with the Admiralty. Leary’s staff provided valuable intelligence summaries based on data from the FRUMEL station and aircraft sightings. 

OpNav’s Office of Naval Intelligence broadcast general information on estimated 

Japanese fleet movements and forthcoming operations. The urgency or special 

nature of intelligence information often required that Nimitz’s and Leary’s intelligence officers send specific dispatches to task force commanders for immediate 

action. 

The Allied cryptanalysts read and decoded in spring 1942 a large number of 

IJN messages directly or indirectly related to Japanese plans for the Second Operational Stage of the war. On 29 January they had decoded the first messages indicating that the Japanese were conducting searches south of Rabaul;188 in February the 

COMINT centers in Hawaii and Melbourne and on Corregidor issued warnings 

to King, Nimitz, and Adm. Thomas C. Hart, commander of the Asiatic Fleet. Admiral Leary received warnings of the Japanese future operations in the direction 

of Lae, Port Moresby, and the Solomons. Collectively, these warnings convinced 

Nimitz in late February that a Japanese offensive was planned for the Port Moresby area. Within a week, U.S. task forces had been alerted.189
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The Allies learned on 21 March of the presence in the New Britain area of two 

cruiser divisions (CruDivs 6 and 18), one destroyer squadron (DesRon 6) and one 

gunboat division (Gunboat Division 8).190 But the first specific indication of the 

pending operation against Port Moresby was a decoded Japanese message of 25 

March: “All attack forces continue operations in accordance with [an unidentified message reference]. . . . On 26th #2 [Air] Attack Force continues to support 

main task and using fighters assist #5 [Air] Attack Force in RZP campaign and 

with scouts carry out patrol in your assigned area. #5 [Air] Attack Force continue 

attacks on RZP and . . . and carry out patrol in your assigned area.”191 Cryptanalysts 

tentatively placed “RZP” in the Port Moresby area. Initially, they believed that both 

RZP and RZQ referred to the Port Moresby area; later they concluded that RZQ 

was a seaplane base in Port Moresby and that RZP was the town itself.192

Reportedly, Allied analysts read all the Japanese messages in April and May 

1942. They were able gradually to discern Japanese intentions from the movements 

of various naval and air units and arrivals at Truk and New Britain. They received 

such a vast number of messages that even without decoding them all they gave 

Nimitz warning in time to move carrier forces into the Coral Sea.193

Good indicators of Japanese preparation for a major offensive operation in the 

southwest Pacific were attempts to disguise radio call signs and the use of a new 

code system. The Japanese intention to mislead the Allies (the deceptive calls were 

those of various air groups in the home islands) was nullified because the Allied 

cryptanalysts read the very message that ordered the practice to be initiated.194 Also, 

prior to the execution of the Port Moresby–Solomons operation the Allied traffic 

analysts learned about the Fourth Fleet’s orders to various units and the times for 

their execution. The Allies were also able to obtain knowledge on search sectors 

given to the Japanese aircraft, detection reports on Allied forces, and the actions 

then taken.195

In April, Allied DI/TI revealed the scope of the pending operation against Port 

Moresby. COMINT regularly recorded movements of the Japanese ships, aircraft, 

equipment, and personnel into the Rabaul area.196 For example, on 1 April COMINT 

learned that two cruisers of CruDiv 6 were present in New Britain, that the remainder of CruDiv 18 and DesRon 6 were in same vicinity, and that the Taichu 

Air Group was expected in the Marshalls–New Britain area shortly. The presence of CruDiv 7 and DesRon 4 south of Bougainville was also noted. On 2 April 

COMINT noted that the Japanese expected enemy air strength in the New Britain 

area to be greatly strengthened in the immediate future.197 COM 14 messages on 

the same day highlighted numerous indications of an impending offensive from 

Rabaul: the enemy was augmenting and reorganizing its air units in the area, and 

there were numerous movements of seaplane tenders from Truk to Rabaul and 

transfers of aircraft to Rabaul.198
The Allied cryptanalysts read on 5 April of the Combined Fleet’s assignment 

of Kaga to the Fourth Fleet; Kaga was an addressee in communications between 

Fourth Fleet and the Combined Fleet regarding the Port Moresby operation. Within a few days cryptanalysts linked Kaga and the “RZP campaign,” understood to 

refer to Port Moresby. On 10 April Allied COMINT deduced that Kaga and a new 

Shōkaku-class light carrier, whose name was erroneously transliterated as Ryukaku

(actually Shōhō) might be used for offensive operations.199 Another indication of 

the possible employment of the Japanese forces in the Coral Sea had come on 7 

April, when the Allies learned that the aircraft based in the Salamaua area had been 

directed to extend their searches up to six hundred miles, from the southeast to 

the south.200 The Japanese commander of an air group in Rabaul informed another 

commander in the Truk–New Guinea area that his unit was conducting searches in 

the sector from 150° to 200° and out to a distance of five hundred miles.201

The Allies decrypted a message on 8 April indicating that reorganization of air 

forces in the Marshalls and New Britain areas was in progress. When completed, 

the Japanese were expected to have in the New Britain area about eighty bombers, 

plus fighters and one squadron of patrol aircraft.202 The next day, analysts decrypted 

a message revealing that Kaga was still at Sasebo but was expected to proceed to the 

New Britain area in the latter part of April.203 On 9 April the Australian FRUMEL 

station decrypted a message from Yamamoto requesting a report on progress of 

repairs on Kaga. He needed Kaga, it said, as soon as possible, because it was to take 

part in the RZP campaign.204

Allied intelligence estimated on 10 April that all the available enemy large carriers were then in the Indian Ocean and that it would be several weeks before 

any would be available to the South Seas Fleet. The U.S. cryptanalysts apparently 

missed the fact that Kaga was not part of the Striking Force, operating in the Indian 

Ocean. However, their British counterparts at Colombo quickly learned of the two 

carriers of the Striking Force that were to operate in the southwest Pacific. They 

decoded almost in its entirety a message sent to Inoue on 13 April advising that 

CarDiv 5 (Shōkaku, Zuikaku), after detaching near Singapore, would stop on 18 

April at Bako, in the Pescadores, and then proceed to Truk, arriving on the 28th. 

The British Admiralty passed this information to King, who in turn warned Nimitz 

and Leary on 15 April.205

On 14 April, the American analysts learned by decoding a radio message that 

“Ryukaku” would arrive at Yokosuka on 20 April and by 25 April at Truk, with more 

than twenty aircraft.206 The same day they learned that CarDiv 5 was near Bako; it 

was expected to be in the Truk area by the end of April. They also believed that 

the movement of CruDiv 5 with two heavy cruisers was possibly linked with the 

deployment of “Ryukaku” to Truk, speculating that CruDiv 5 would be assigned to 

the Fourth Fleet.207 A British radio intercept on 15 April indicated that the Japanese 

carrier striking force was leaving the Indian Ocean and that CarDiv 5 would be 
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detached to proceed to Truk, arriving about 21 April. This, combined with a report 

of Capt. Joseph Rochefort, the officer in charge at HYPO, on the southward movement of the Japanese units and supplies, convinced Nimitz that an “offensive in the 

southwest Pacific is shaping up.”208

On 17 April, the Australian Combined Operational Intelligence Centre (established on 5 March 1941) in Melbourne outlined “indications of an imminent 

move by Japan against Australian territory.” It concluded that the enemy intended 

to carry out an offensive from the Truk–New Britain area, probably during the first 

week of May, with the major objective of seizing control of the New Guinea–Torres 

Strait area, involving the occupation of Port Moresby. The review also stated that 

the aircraft carriers Zuikaku and Shōkaku were in transit from Formosa to Truk, 

to arrive on 28 April. The report estimated that the Japanese naval forces for the 

pending offensive would consist of two or three aircraft carriers (Zuikaku, Shōkaku,

and “Ryukaku”), five heavy cruisers, four light cruisers, twelve destroyers, and a 

submarine force.209

Also on 17 April, a message from COM 14 highlighted the activity of the enemy 

aircraft in the Rabaul area. It noted that the Tainan Air Group had been operating 

from the Rabaul area since 7 April. That unit would receive on 25 April nine divebombers being carried by “Ryukaku.” The 5th (Air) Attack Force was composed 

of heavy bombers and patrol aircraft and was involved in the operations over Port 

Moresby.210 COM 14 pointed out a large increase in the Japanese air strength in the 

New Britain area; a new air group (the Taichi Air Group) had arrived at Rabaul. It 

also believed that “Ryukaku” and CruDiv 5 might be connected with movements 

of shore-based units into Rabaul area.211 On 21 April U.S. COMINT reported that 

the Tainan Air Group had arrived at Rabaul on the 10th. The seaplane tender Kenjo 

Maru was in Rabaul, and another tender, Fujikawa Maru, was en route from Palau 

to Rabaul.212

On 21 April, station BELCONNEN, together with the radio intelligence team 

of the Royal Australian Navy (RAN), estimated that intensified air attacks on Port 

Moresby clearly showed that it was the main Japanese objective. Nimitz decided to 

direct TF 17 (then in the vicinity of the Coral Sea) and TF 11 (two days out of Pearl 

Harbor and heading south) to block the Japanese move against Port Moresby.213

Admiral King requested HYPO’s analysis of the situation in the southwest 

Pacific. Rochefort indicated in his reply, on which Nimitz was an “information” 

addressee, that there was a consensus that the Japanese operations in the Indian 

Ocean had ended and that the Japanese planned a new offensive against eastern 

New Guinea and in the Coral Sea. The enemy objectives were not clear, but there 

was no evidence that the Japanese intended to invade Australia. A light carrier 

(“Ryukaku”) had been assigned, along with a cruiser division, to cover movements 

into the Rabaul area.214
MacArthur’s intelligence section was very skeptical about Japanese intentions 

against Port Moresby. On 21 April, Col. Charles A. Willoughby, MacArthur’s assistant chief for intelligence, prepared for his chief of staff, Lt. Gen. R. K. Sutherland, 

a status report based on (but not attributed to) COMINT from Melbourne. 

Willoughby questioned the Navy’s view of Japanese naval and ground-based air 

strength in the Fourth Fleet area. He (erroneously) believed the buildup posed more 

of a threat to the coast of Australia and New Caledonia than to Port Moresby.215

On 22 April, there were strong indications of an impending concentration of 

Japanese forces in the Truk area, involving CarDiv 5, CruDiv 5 (less heavy cruiser 

Nachi), “Ryukaku,” and DesDiv 4. CarDiv 5 was expected to arrive at Truk on 28 

April and thereafter probably to move to the New Britain area. The carriers Sōryū

and Ryūjō were en route to Japan. Additional heavy bombers had arrived at the 

Rabaul area on 19 April. For the cryptanalysts, it was obvious that a major fleet 

operation centering on the New Britain area would start very soon.216

On 23 April, messages decoded by HYPO and NEGAT and a report from Melbourne indicated that the Port Moresby force included CruDiv 5, CarDiv 5, and possibly submarines and the light carrier “Ryukaku.” However, it erroneously placed Kaga 

in the Truk area.217 The Allies learned the same day that Inoue had issued Operation 

Order No. 13 to the South Seas Fleet to initiate operations against Port Moresby.218

On 25 April, Op-20G intercepted a very important message sent by the Fourth 

Fleet the preceding day. That message directed subordinate commands to amend 

the naval call list and thereby revealed the task organization for the Port Moresby–

Solomons operation. Specifically, the No. 3 Truk (Fourth Fleet) Communications 

Section was on 25 April to change page 5 of “naval call list number 117,” inserting 

the following addressees: MO Fleet, MO Occupation Force, MO Attack Force, RZB 

Occupation Force, RY Occupation Force, and 3rd and 5th Special Base Forces. The 

analysts asserted that designator “MO” stood for Port Moresby and “RXB” for Tulagi; “RY” was not definitely known but was believed to be the Gilbert Islands.219

The Allies learned on 25 April that reinforcements continued to arrive at New 

Britain. The units of Gunboat Division 8 were en route from Sasebo to Rabaul.220

On the 26th American analysts deduced that three carriers—“Ryukaku,” Zuikaku,

and Shōkaku—were en route to Truk and would arrive there about 26 April.221 Another strong indicator of the pending operation against Port Moresby was a request 

on 18 April for a thousand copies of some documents, including charts of Australia, to be sent via transport aircraft departing Yokohama on 20 or 21 April.222 The 

Allied analysts believed that on that day the seaplane tender Kasuga Maru was at 

Truk or south of Truk.223 Cryptanalysts falsely believed that the 5th Air Attack Force 

was based in the Carolines (actually in New Britain) and that the urgency of sending these documents indicated that it would be actively engaged in “that sector 

[Australia] shortly.”224
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On 27 April Allied cryptanalysts noticed increased air and submarine activity. A decoded message dated 21 April indicated the employment of SubRon 7. 

SubRon 8 was believed to have been in the Rabaul area on 22 April. The CINC of 

the Fourth Fleet addressed CarDiv 5, CruDiv 5 (less Nachi), the cruiser “A KU 3,” 

and DesDiv “RI TE 9” (the latter believed to be DesRon 1, plane guards for CarDiv 

5). COM 14 mistakenly placed the 4th, 5th, and 6th Air Attack Forces in Rabaul; 

the 3rd, it assessed, was in Malaya and the 1st between Wake and Rabaul.225 Actually, only the 5th AAF was in Rabaul. Air reinforcements for the New Britain area 

were arriving from the Marianas and the Marshalls. CarDiv 5, CruDiv 5, and several destroyers were reported operating to the southward of Truk. The Allies also 

learned that the Japanese had detected an Allied task force composed of one carrier, 

one cruiser, and two destroyers at about 230 miles southeast of Rabaul at 1200 on 

26 April.226

Especially valuable was a Japanese message decoded on 27 April that read, “The 

Mandates force will operate as follows. Comdr . . . , with four unidentified units 

[probably those in the heading], departs Truk and join . . . for operation against 

enemy in RX area. If no contact is made search with RQ as reference point [the next 

part was vague but dealt with responsibilities and orders of various units and ships]. 

With reference to operations of the First Air Fleet and . . . these orders remain in 

effect until canceled.”227 Also on 27 April, the commander of the Fourteenth Naval 

District at Pearl Harbor reported his belief that air reinforcements for New Britain 

would arrive from the Marianas and Marshalls in the immediate future. There were 

more indications that CarDiv 5 and CruDiv 5 (less Nachi) and destroyers would 

operate southward of Truk.228

On 28 April, COM 14 learned that the Fourth Fleet had directed four units 

to join another group to search for and engage the enemy eastward of New Britain. The analysts believed that this other force consisted of units from CruDivs 

6 and 18, strengthened by at least one carrier, “Ryukaku,” and perhaps two heavy 

cruisers of CruDiv 5.229 The commander of the Fourth Fleet now sent an urgent 

dispatch that represented an operation order for offensive operations in the southeast theater. The addressees were the Fourth Fleet, CruDiv 5, CarDiv 5, “Ryukaku,”

Kamikawa Maru, two or three destroyer divisions, plane guards, the commander of 

submarine forces, and the 4th and 5th Air Attack Forces.230

In late April, a serious breach of security happened in MacArthur’s headquarters. On 27 April several newspapers in Washington, D.C., published a story that 

read, “Japanese naval forces including ships, planes, supplies and men are concentrating in Marshall Islands apparently preparing for new operations.” King was furious and sent a sharply worded protest to Marshall. On the 30th the War Department warned MacArthur to tighten censorship at his headquarters. This story was 

potentially dangerous because it might have indicated to the Japanese that their 
codes had been broken. However, nothing happened; Japanese agents apparently 

did not pick up the story.231

The main sources for tactical (as opposed to strategic and operational) intelligence were the reports of land-based reconnaissance aircraft based in northeastern Australia and at Port Moresby, flying boats at Nouméa, submarines, and the 

coast-watcher service. The SWPA’s search of the prospective operating area was 

hampered by long flying distances and corresponding long transits. Flights had to 

be staged through Horn Island. The lack of good bases and of adequate numbers of 

patrol aircraft was sorely felt.232

In preparation for the operation, as he informed Fletcher, MacArthur modified existing search plans. Specifically, SWPA aircraft flew flank-reconnaissance 

patrols around Thursday Island, Port Moresby, and Rabaul. They also extensively 

reconnoitered the Solomon Islands and the area southeastward to the boundary 

of the Southwest Pacific Area, as well as the Solomon Sea west of Tulagi. In addition, SWPA aircraft patrolled from Buna southeastward along the north coast of 

New Guinea and the Louisiades, and then westward, south of the Louisiades, to 

Port Moresby. The area around Townsville was patrolled out to five hundred miles. 

Allied search aircraft conducted routine patrols across the mouth of the Gulf of 

Carpentaria and off Darwin. SWPA bombers and fighters at Port Moresby also 

often conducted photographic and armed reconnaissance around Salamaua, Lae, 

Madang, Gasmata, and Buna. After 1 May, however, no searches east of the Solomon Islands were conducted by either the RAAF from Tulagi or the U.S. Army Air 

Forces in Australia or at Port Moresby.233

Prior to 2 May, the SWPA’s Allied Air Forces operated only three bases for reconnaissance missions. The lack of aircraft and flying boats prevented scouting more 

than one of the allocated search areas more often than once a day. The search areas 

barely overlapped and only in two locations: the Solomon Sea and the Solomons. 

The area around the Louisiades was covered by aircraft flying from Townsville, 

Port Moresby, and Tulagi. After Tulagi was abandoned on 2 May, the area over the 

Solomons south of Bougainville and that between Rossel and Rennell Islands were 

left uncovered. The loss of Tulagi was not offset by changing the boundary between 

the SWPA and POA; almost the entire area in which the battle of the Coral Sea was 

to take place was within the SWPA.234

Subordinate to Nimitz was the seaplane tender Tangier, at Nouméa; it had six 

Catalinas available for search. From 1 through 4 May they flew daily patrols in a 

northwesterly sector out to seven hundred miles. Three Catalinas were used in parallel searches separated by fifty miles (their assumed radius of visibility was twentyfive miles).235 Because of their small numbers, the Catalinas could search only once 

a day. This was not sufficient to ensure detection of enemy forces entering the Coral 

Sea from the eastward around San Cristobal Island or through any of the passages 
J

northwestward of that island. Had the Catalinas redeployed to, or staged through, 

Efate, their effective search could have been extended up to 180 miles on the western leg, far enough to include Tulagi, and 210 miles on the eastern leg, seventy-five 

miles to seaward of Malaita. This would probably have resulted in detection of the 

Japanese carrier force on 5 May. Conducting the search from Espiritu Santo Island 

would have extended the radius even farther to the northwest to the tip of Choiseul Island, providing coverage seventy-five miles to the eastward of the Solomon 

Islands.236

Divided theater command hampered significantly the process of obtaining 

comprehensive and timely information on the whereabouts and movements of 

enemy forces both prior to and during the operation. MacArthur had sole responsibility for land-based aircraft operating over the Coral Sea, on which, by 

decision of the Joint Chiefs of Staff, Nimitz was not allowed to intrude; the consequence was that a large part of the Coral Sea was not searched.237 Another problem was that Allied land-based aircraft crews were poorly trained for maritime 

reconnaissance. The long flying hours caused fatigue. Also, the number of landbased search aircraft was limited; during the operation, CTF 17, Rear Admiral 

Fletcher, would be forced to supplement them with carrier-based planes.238

The coast-watcher service had been organized in 1939 by the RAN, which 

had been made responsible for establishing such a service on the northern 

Australian mainland, the Torres Strait islands, New Guinea, New Britain, and 

the Solomon Islands. Coast watchers were drawn from civilian administration 

officers, teachers, planters, missionaries, and other coastal residents. By 1939 

close to seven hundred volunteer coast watchers had been recruited; in early 1941 

Townsville became the coast-watching service’s coordination center. An Area 

Combined Headquarters was also established in Townsville in January 1941 to 

coordinate the defense of maritime shipping. The coast-watcher service reported 

on shipping movements and other unusual activities along some 2,485 miles of 

coastline of Australian New Guinea, the Admiralties, the Bismarck Archipelago, 

the Solomons, and the New Hebrides.239

The Allies had relatively good knowledge of the Japanese air facilities and 

air strength in the newly occupied areas of eastern New Guinea, the Bismarck 

Archipelago, and the Solomons. However, they estimated inaccurately that on 25 

April the Japanese had sixty-eight aircraft (fourteen fighters, forty bombers, and 

fourteen patrol aircraft) deployed in Rabaul and about twenty-four aircraft (all 

fighters) at Lae.240

Allied Plans and Preparations 

In early 1942 Australian Papua New Guinea was weakly defended and open to 

Japanese attack. By early April 1942 Port Moresby had a small garrison of three 

infantry battalions and several gun batteries.241 Despite public statements that he 
was committed to the defense of Australia by holding New Guinea, MacArthur 

deployed only one brigade of militia to Port Moresby and sent no reinforcements 

until 14 May, when the battle of the Coral Sea was over, although he had four experienced Australian Imperial Force brigades and the U.S. 41st Division. The SWPA 

had to rely almost exclusively on land-based aircraft and naval forces to defend Port 

Moresby.242

The SWPA’s Allied Air Forces, under Lt. Gen. George Brett (who had taken the 

post on 20 April 1942), consisted of six groups—three pursuit, one light bombardment, one medium bombardment, and one heavy bombardment—and four RAAF 

squadrons. This force was impressive, but only on paper. There were about a hundred medium bombers and forty-eight heavy bombers, but less than half were operational.243 Brett deployed at Port Moresby three Australian search squadrons and 

one fighter squadron, plus one U.S. squadron of dive-bombers. The major part of 

the Allied air forces was at airfields in Townsville, Cooktown, and Charters Towers. 

Squadrons were sometimes able to put no more than a single plane in the air. Out 

of about five hundred aircraft in the Allied Air Forces inventories, only about two 

hundred, or 40 percent, could support the Coral Sea operation.244

SWPA Allied Naval Forces, under Vice Admiral Leary, were small and inadequate for defending Port Moresby from an enemy landing. Most of the SWPA’s 

surface forces were actually controlled by Fletcher. The submarine force consisted 

of eleven old, S-class boats. Only four to six could be on patrol at any given time; 

they were usually employed around Rabaul and off the eastern New Guinea coast.245 

The Australians were unable to hold their position in the Solomons, because of the 

lack of air cover; they had at Tulagi only about fifty men and a seaplane base with 

four Catalinas, which patrolled out to New Britain and Bougainville. They decided 

on 2 May to evacuate Tulagi after receiving warning from the coast watchers that 

an enemy force was on the way from Rabaul.246

In early April, Nimitz had only one carrier task force at sea—TF 17, with Yorktown, under Fletcher—in the eastern part of the Coral Sea. Task Force 11, with 

Lexington, had steamed into Pearl Harbor on 26 March. Lexington was planned to 

complete docking and refit by 15 April. Task Force 16, under Vice Admiral Halsey, 

in Enterprise, was at Pearl Harbor. The new TF 18, Capt. Marc A. Mitscher’s new 

carrier Hornet with several escorts, was expected to sail in the first week of April 

from the West Coast to Hawaii. On 2 April, Nimitz’s staff discussed whether TF 11 

should join TF 17 in the southern Pacific or remain in Hawaii and train together 

with TF 1, commanded by Vice Adm. William S. Pye and composed of old battleships. On 3 April, Rear Adm. Aubrey Fitch relieved Vice Admiral Brown as CTF 

11. Nimitz directed Fitch to sail on 15 April and exercise near Palmyra until 4 May, 

when TF 1 would return to Pearl Harbor. Four days later he informed Fletcher that 

he had taken over command of the SOPAC. Nimitz directed Fletcher to sail east to 
J

Tongatabu for replenishment. Task Force 17 would depart Tongatabu on 27 April 

and head back to the Coral Sea. 

Since the 10 March attack on shipping in the Huon Gulf, there had been no 

significant actions by Allied carriers in the South Pacific. However, MacArthur 

wanted them to remain in the area, and on 17 April he expressed concern that carriers were leaving the Coral Sea for Tongatabu. He wrote to Nimitz, “[I] consider it 

necessary that one task force [be] maintained in that area at all times to check further enemy advance.” Nimitz was surprised at the message but assured MacArthur 

that TF 17 was being withdrawn only to replenish and deal with problems with its 

fighter aircraft. He strongly agreed on the desirability of maintaining a force in the 

Coral Sea and would try to do so.247 But Nimitz privately told King, “It is my conviction that enemy advance should be opposed by force containing not less than two 

carriers.” He again recommended to King that TF 11 be sent to the Coral Sea to join 

TF 17. Nimitz did not want TF 1 to be employed beyond the Palmyra–Christmas 

line and in fact wanted it returned to San Francisco.248

Although he held the posts of CINCPOA and CINCPac, Nimitz did not have 

control over Enterprise and Hornet in April 1942. In January 1942 King and his 

staff planned a diversionary raid (later popularly known as the “Doolittle Raid”) 

on Japan to raise the nation’s morale after a string of Allied defeats in the Pacific. In 

consultation with General Arnold, King decided to use Hornet, which would carry 

sixteen B-25 long-range heavy bombers of the 17th Bombardment Group (Medium), under the command of Lt. Col. James H. Doolittle. Enterprise, under Halsey, 

would accompany the raiding force in support. The two task forces joined on 13 

April, and Halsey incorporated Hornet into TF 16. The bombers would be launched 

at a distance of 450 miles from their targets on 18 April. From decoded enemy radio messages, U.S. planners knew that the Japanese carriers were still far south of 

Japan and would not interfere with the operation. However, this diversionary raid 

resulted in half of Nimitz’s carrier strength being tied up and unable to take part 

in the operations elsewhere in the Pacific. Otherwise, Nimitz would have had four 

carriers (Lexington, Yorktown, Hornet, and Enterprise) to oppose the thrust toward 

Port Moresby and probably would have inflicted much larger losses on the Japanese.

Halsey’s TF 16 (Enterprise, plus Hornet attached for the Tokyo raid) was expected to return to Pearl Harbor on 25 April. It could sail for the South Pacific by 

the end of April and join Fletcher’s TF 17 on about 14 May. The only concern was 

whether Hornet would have its full complement of aircraft. A force of seven fleet 

tankers could support both carrier task forces in the South Pacific until about 1 

June. Afterward, chartered tankers would have to be diverted from West Coast–

Hawaii runs to Fiji and Samoa. Task Force 16 would operate with TF 17 and then 

relieve it when Fletcher left the South Pacific about 15 May, because Yorktown

needed dry docking and overhaul. Lexington could stay until 1 June, when it 
would go to Hawaii for dry docking as well. The Catalinas at Nouméa would be 

increased from six to twelve. The SWPA would provide land-based air support. 

A group of cruisers and a half-dozen submarines would be deployed from Hawaii 

to the South Pacific and five more to observe Truk.249

Plans to counter the pending Japanese offensive against Port Moresby were prepared independently by the SWPA and POA staffs. On 4 April, an Australian study 

argued that the key to the defense of Australia was Port Moresby.250 After the Japanese occupation of Rabaul and points on the New Guinea coast, MacArthur decided to strengthen Allied positions in New Guinea and develop Port Moresby as a 

major air and land base. Though, as noted above, he sent no troops to Port Moresby, 

he directed the expansion of air facilities in northeastern Australia, specifically 

at Townsville and Cloncurry, for its defense; this program was in its early stages 

in late April 1942. MacArthur also made extensive preparations to thwart the 

Japanese attempt to seize Port Moresby. Among other things, he directed SWPA’s 

Allied Air Forces to intensify reconnaissance and concentrate striking forces at 

Townsville and Cloncurry airfields. He planned to conduct repeated air attacks 

against Rabaul in early May; long-range heavy bombers would also attack Lae, 

Deboyne Island, and convoys in adjacent areas. The garrison commanders in 

northeastern Australia and at Port Moresby were alerted to the possibility of the 

enemy landings. Allied Naval Forces also sent three cruisers, organized as TF 44, 

under Rear Admiral Crace to join with TF 17 in the Coral Sea.251

For its part, Nimitz’s staff produced on 22 April a detailed estimate of the 

situation. It assumed that a Japanese offensive in the New Guinea–New Britain–

Solomons area would begin about 3 May. For Nimitz the problem was how to 

stop the pending Japanese advance in the southwestern Pacific and yet ensure 

the security of Hawaii and of lines of communications with the West Coast. He 

delegated authority to conduct operations directly to Fletcher. When TF 16 arrived, Halsey would take overall command.252 Had Halsey’s carrier group entered 

the Coral Sea, therefore, he would have commanded all Allied naval forces in the 

battle.253 

To divert Japanese attention from the movements of the U.S. forces in the 

South Pacific, Nimitz planned to send the light cruiser Nashville from Pearl Harbor on 2 May to the Japanese fishing grounds off Kamchatka (after stopping at 

Midway) to destroy fishing boats. Nashville would transmit messages mimicking 

the presence of a U.S. carrier task force. However, Nashville ran aground leaving 

Midway, and the mission was abandoned. 

The U.S. carrier groups in the Coral Sea had only two fleet oilers for underway 

refueling: the 21,077-ton, 16.5-knot Neosho, and the 17,070-ton (full), ten-knot 

Tippecanoe. There were two more oilers available in Australia, but they were not 

equipped for underway replenishment. Carriers and their escorts consumed very 
J

large quantities of fuel, especially at high speed in combat. Fortunately, carriers 

and cruisers could carry sufficient fuel to give them long range and endurance. For 

example, Yorktown carried 7,500 tons of fuel, enough for seventeen days at twenty 

knots. But the 1,900-ton U.S. destroyers of 1942 carried only about five hundred 

tons of fuel, giving them an endurance at fifteen knots of about 4,700 miles, or 

thirteen days. At thirty-four knots—in combat action or when screening fast carriers—their endurance was only thirty-two hours, about 1,100 miles.254 Carriers and 

cruisers often refueled the short-legged destroyers and more quickly than oilers 

could, but to do so the entire task group had to be withdrawn from the operating 

area.

The shortage of fleet oilers was a major Allied weakness and potential vulnerability. Fletcher tried always to keep an oiler with his carrier group, except during 

the actual strike operations. He was also greatly concerned that the Japanese not 

discover that he had only two fleet oilers. If the Japanese attacked them, U.S. carrier 

operations in the Coral Sea would be severely restricted.255 

Compared to the Japanese plans, the Allied plan was simple and straightforward. The single and the most important objective was to prevent the enemy invasion forces from reaching and landing troops at Port Moresby. The prerequisite was 

to deny local control of the Coral Sea to the enemy. This objective could be accomplished by the destruction or neutralization of the enemy’s greatest critical strength, 

his carrier force—in modern terms, his operational center of gravity. 

Nimitz issued his Operation Plan 23-42 to Halsey on 29 April. In it he instructed 

Halsey to oppose the enemy advance in the New Guinea–Solomon Islands area. 

Nimitz explained that there were indications that the Japanese would launch an offensive in the southwest Pacific in the first week of May 1942. Probable objectives 

were Port Moresby, the Solomon Islands, and further positions in the Gilbert Islands, with a “possible extension of effort to include strong raids against New Caledonia and/or Fiji islands.”256 Nimitz directed that TF 17, composed of the existing 

TF 17 plus TF 11, would operate in the Coral Sea starting on 1 May. These forces 

would be put under command of CTF 16 (Halsey) upon his arrival in the Coral Sea. 

Depending on the situation, TF 17 might be withdrawn to the Central Pacific about 

15 May and TF 11 about 1 June. The seaplane tender Tangier and its twelve patrol 

aircraft, based at Nouméa, would operate as directed by the senior task force commander in the area, as Task Group 17.9.257 Nimitz also informed Halsey that General 

MacArthur had directed his submarine force to start patrolling on 28 April the Port 

Moresby–Rabaul and Louisiades–Samarai Island areas. SWPA forces would search 

the general area, coordinating their actions and cooperating with the other naval 

task forces operating in the South Pacific. MacArthur had made available the Australian cruisers Australia and Hobart, the U.S. cruiser Chicago, and two 1,200-ton 

destroyers for the operations with the Pacific Fleet task forces. It had been agreed by 
the Allied governments that the senior U.S. naval officer commanding a carrier task 

force would, regardless of relative rank, exercise tactical command of the combined 

units operating in the southern and southwest Pacific.258

On the basis of Nimitz’s Operation Plan 23-42, Fletcher issued his Operation 

Order No. 2-42, in which he stated that the mission of TF 17 was to “destroy enemy 

ships, shipping, and aircraft at favorable opportunities in order to assist in checking further advances by enemy in the New Guinea–Solomon area.”259 He also wrote, 

“This force will operate about seven hundred miles south of Rabaul. Upon receiving intelligence of enemy surface forces advancing to the southward, this force will 

move into a favorable position for intercepting and destroying the enemy.”260 An 

annex to the operation order contained information on the Japanese air strikes 

against Horn Island, Port Moresby, and Tulagi. It estimated the enemy’s land-based 

air strength at 102 aircraft (forty-two fighters, thirty-six bombers, twenty flying 

boats, and four floatplanes). The enemy searches would, it assessed, extend out to 

six hundred miles from Rabaul and the Shortland Islands. Fletcher anticipated that 

the enemy offensive would start around 28 April. 

Fletcher’s estimate of the enemy’s carrier forces was largely accurate. Among 

other things, it stated that the frontline carriers Zuikaku and Shōkaku had sixtythree aircraft each (twenty-one fighters, twenty-one dive-bombers, and twenty-one 

torpedo bombers). However, “Ryukaku” was wrongly estimated to carry eighty-four 

aircraft (twenty-one fighters, forty-two dive-bombers, and twenty-one torpedo 

bombers; the air complement of the actual Shōhō was much smaller). In addition, it 

was believed that the 17,400-ton converted carrier Kasuga Maru would be present, 

carrying some forty-five aircraft. These forces were supported, the order stated, by 

two heavy cruisers, three light cruisers, sixteen destroyers, two converted seaplane 

tenders, one submarine tender, six submarines, eight gunboats, and nineteen transports and auxiliary vessels.261

Execution

The Port Moresby-Solomons operation was executed between 27 April and 11 May 

1942. Combat took place between 3 and 8 May, and the decision was reached in 

a carrier engagement on 8 May (see map 4). In the process both sides made numerous errors in identifying opposing forces. Many wrong decisions were made 

because commanders either received incorrect information on the whereabouts 

and movement of enemy forces, lacked that information entirely, or exercised poor 

judgment.

The major combat involved in the operation can be divided into three phases. 

Phase I comprised the deployment of combat forces and the Japanese landing on 

Tulagi (27 April–3 May), II the Allied attack on Tulagi and preliminaries (4–7 May), 

and III the carrier engagement and withdrawal of forces (8–11 May). 
J

Map 4

The execution

29

April–3 May

7 May–11 May

7 May–11 May

29 April–3 May

x

x

0 5 MILES

150°E 155°E 160°E

5°S

10°S15°S

160° 155°

5°

10°

0 50 100 150 200

MILES

REFUELING

C O R A L S E A

Attack group launched

DD Sims

sinks

1130

7 MAY

AO Neoshosinks155011 May

CV Lexington sinks19568 May

Debarking Pt. No. 1

Cleared channel

22009 MAY

20009 MAY

Main Landing PARI

144i(I) 1 mt arty bn

Anchorage

DAUGO IS

Barracks

Military installationCoast artillerySeaplane base

22009 MAY

Debarking Pt. No. 2

HAIDAN

I/ 144i

A

ROKU

HUHUNAMO

PORTMORESBY

PORT MORESB

Y IN

VASION PLAN

North Airfield

Kilakila Airfield

BASILISK ASSAGE P Legend 1030

0500

10 MAY

0600 7 MAY

1130

1800

2000

1300

0900

1630

04007 MAY

24006 MAY

24007 MAY

04008 MAY 0710

8 MAY

Attack group launched0822–0915

Attack group launched

0840–0915

07008 MAY

1100

2400

8 MAY

0200

9 MAY 0730

6 MAY

GUADALCANAL

SANCRISTOBAL 2400

5 MAY

0715

11 MAY

RENNELL

1500

TULAGI

11305 MAY

MALAITA

SANTA ISABEL

CHOISEUL

BOUGAINVILLE 

STRAIT

NEW GEORGIA

GROUP

KIETA

BUKA

SOLOMON SEA

BOUGAINVILLE

10507 MAY

MISIMA DEBOYNE

D’ENTRECASTEAUXIs

WOODLARK

MILNE BAY

GOODENOUGH

BUNA

PORT MORESBY

HUON GULF

VITIAZ STRAIT

DAMPIER STRAIT MADANG

PAPU

A

C. GLOUCESTER

OWEN STANLEY RANGE

BISMARCK SEA

C. ST. GEORGE

RABAUL

BISMARCK

ARCHIPELAGO

TALASEA

24004 MAY NEW

BR

TI A

NI

NEW IRELAND

GASMATA

LAE

SALAMAUA

JOMARD

PASSAGE

CHINA STRAIT

SOLOMON

ISLANDS

LEGEND

MO CARRIER FORCEMO INVASION FORCETULAGI INVASION FORCEMO MAIN FORCEMO SUPPORT FORCE

00005 MAY

08003 MAY

TF 11

LILJEBLAD

ASSAGE P

2400

10 MAY

TF 17 0800

9 MAY 0700

3 MAY

20004 MAY

08003 MAY

19305 MAY

00105 MAY

0630

4 MAY

ALLIES

TF 17 (ENLARGED)TF 17TF 11TF 44TG 17.3TG 17.6

JAPANESE

TG 17.3

SHORTLAND

PADANA NAFUA

1400

7 MAY

TO

AUSTRALIA

TG 17.3DETACHED0645 7 MAY

0900

4 MAY

TFs 11 & 44

JOIN

0730

6 MAY

TFs 11 & 44

JOIN TF 17

15304 MAY

TIME ZONE (-11)

WEATHER FRONT

24006 MAY

11357 May

ROSSEL 

19306 MAY

TF 44 from Australia

0820

3 MAY

09454 MAY

0820

3 MAY

2400

4 MAY
Phase I (27 April–3 May)

The Japanese forces deployed for the Port Moresby–Solomons operation in nine 

force elements, each proceeding toward its assigned area independently. On 29 

April four submarines of SubRon 8 (I-22, I-24, I-28, and I-29) left Rabaul and headed to their assigned patrol area some 285 miles southwest of Guadalcanal; another 

submarine (I-21) took up a station off Nouméa. In early May, two boats of SubGru 

21 (RO-33 and RO-34) sailed out of Rabaul for the waters south of Osprey Reef, 205 

miles north-northeast of Cairns, Australia; they were then to proceed to the approaches of Port Moresby.262 On 29 April, the MO Support Force sailed from Truk 

southward to pass west of Buka Island and then turn south and eastward toward 

a position west of Tulagi. The next day the MO Main Force sortied from Truk, 

steamed southward toward the passage between Bougainville and Choiseul, and 

then pushed eastward toward a point some 150 miles west of Tulagi. The Tulagi Invasion Force, with about four hundred troops of the 3rd Kure Special Unit, sortied 

from Rabaul on 29–30 April. The MO Carrier Force sailed from Truk on 1 May to 

pass eastward of San Cristobal and enter the Coral Sea. Finally, on 4 May the MO 

Invasion Force, with five thousand troops of the South Seas Force and five hundred 

of the 3rd Kure Special Unit, sailed from Rabaul and proceeded southward toward 

Jomard Passage.

On the Allied side, TF 17 spent seven days at Tongatabu for provisioning and 

upkeep. It sailed out of Tongatabu on 27 April and three days later reentered the 

Coral Sea. In the meantime Task Force 11 left Pearl Harbor for the South Pacific. 

At 0615 on 1 May TF 17 and TF 11 met some three hundred miles southwest of 

the New Hebrides. Task Forces 17 and 11 were vulnerable there to surprise enemy 

attack, because, as noted, Allied land-based aircraft did not patrol the central and 

eastern parts of the Coral Sea and there was no coverage of a potential approach by 

the enemy carrier forces eastward of the Solomon Islands.263 Fletcher sent TF 11 to 

join the oiler Tippecanoe, with the cruiser Chicago and destroyer Perkins, at latitude 

16° 00′ south, longitude 161° 45′ east, to take on as much fuel as possible before the 

oiler returned to Efate as directed by Nimitz and to rejoin TF 17 the next morning. 

Fletcher wanted to leave as much fuel as possible on Neosho as a reserve.264

Allied cryptanalysts continued to provide valuable information to Nimitz, 

Fletcher, and Fitch. For example, on 29 April, COM 14 decoded several messages 

sent by the Fourth Fleet clearly indicating that the MO Operation was under way. 

Fourth Fleet’s Operation Order No. 13 was read in its entirety. It stated that the 

objective of the MO Operation was, first, “to restrict the enemy’s movements and 

[this] will be accomplished by means of attacks on outlying units and various areas 

along the north coast of Australia. The Imperial Navy will operate to its utmost 

until this is accomplished. Further we will continue to operate against all bases used 

by enemy aircraft.”265
J

On 30 April, COM 14 reported that the enemy units active in the New Britain 

area were CruDiv 5, CarDiv 5, “Ryukaku,” and Kamikawa Maru. Kasuga Maru was 

due at Kwajalein on 2 May. COM 14 reaffirmed that the impending offensive was 

meant to capture Port Moresby; the Japanese had intensified aerial reconnaissance 

of Cape Nelson, Samarai Island, and Cape Rodney, combined with intensified 

bombing of Port Moresby and Tulagi. A decoded radio message identified the Port 

Moresby Occupation Force, the Deboyne Detachment, the Rodney Detachment, 

and the Samarai Detachment.266

On that same day, the Allied analysts learned from a decoded message that 

two Japanese merchant vessels had been ordered to depart about seven days 

prior to the Port Moresby landing and rendezvous with the Saipan base force 

off Deboyne Island. The message also mentioned Samarai and Cape Rodney. All 

these places were in the southeastern part of New Guinea and were good indications of Japanese intentions. The message also revealed that the enemy planned 

to capture Samarai and Tulagi.267 The Fourth Fleet ordered a search for the Allied 

naval task force, sending air patrols into the sector 080°–120° from Rabaul to a 

distance of seven hundred miles. Air patrols from Maloelap and Kwajalein in the 

Marshalls were extended to six hundred miles.268 Nimitz’s fleet intelligence officer 

(Lieutenant Commander Layton) commented that the Port Moresby operations 

“will begin very soon.”269

Also on 30 April, the Japanese tried to change their locator system. However, 

HYPO intercepted a Fourth Fleet message that contained lists of both old and new 

designators. That message had been sent to CruDiv 5, CarDiv 5, the Eleventh Air 

Fleet, the 4th and the 5th Air Attack Forces, the seaplane tender Kamikawa Maru,

the carrier “Ryukaku,” destroyer divisions, and air personnel in the Rabaul area.270

From it HYPO constructed a remarkably accurate Japanese order of battle for the 

Port Moresby–Solomons operation. The Allied cryptanalysts also deduced that the 

operation was already under way but that Australia was not among its objectives. 

They learned that the major force elements taking part in the operation included 

CarDiv 5, CruDiv 5 (less Nachi), CruDiv 18, DesRon 6, and Gunboat Division 8. 

The air units based in the Rabaul area were the 5th AAF with the Tainan Air Group 

and the 4th Force (Yokohama Air Group). Vice Admiral Takagi with CruDiv 5 was 

commander of the Carrier Striking Force, while the CINC of the Fourth Fleet was 

in overall command of the operation. An unspecified number of seaplane tenders 

and transports, the light carrier “Ryukaku,” and one submarine squadron were also 

part of the operation. Melbourne analysts disagreed with some points of HYPO’s 

analysis. However, both stations agreed that the Port Moresby–Solomons operation 

was in progress. The Japanese surface forces taking part were estimated at three 

hundred ships of all types, including three carriers, nine heavy cruisers, fourteen 

destroyers, eight submarines, and thirty-three other warships.271
Extensive security measures were introduced throughout the Combined Fleet 

on 1 May, extending through 5 May. In the Fourth Fleet, changes in the tactical 

call signs of ships and the call signs of all shore stations, the use of false call signs 

by ships of the Port Moresby force, and a marked increase in the volume of highpriority communications complicated temporarily the task of analyzing the fleet 

communications structure.272

On 1 May, COM 14 concluded from the analysis of intercepted and decoded 

enemy messages that the “MO campaign” was under way. The area involved was 

southwestern New Guinea and the Louisiades. The enemy forces will consist of 

CarDiv 5, CruDiv 5 (less Nachi), CruDiv 18, DesRon 6, Gunboat Division 8 (now 

called 19th Division); New Britain Air which is known as 5 Air Attack Force and 

consists of Tinian Air Group, 4th Air Corps, and Yokohama Group; first two land 

bombers and fighters; the last one of seaplanes. The Fourteenth Naval District 

estimated that the enemy had sixty-five bombers, sixteen scouting aircraft, and 

an unknown number of fighters. It also believed that the carrier “Ryukaku” and 

one submarine squadron were part of the operation. It estimated that CruDiv 5 

and the CINC of the Fourth Fleet would arrive at Rabaul on 1 May. COM 14 also 

correctly concluded that although the enemy message included Townsville as a 

reference point, Australia would not be attacked in the near future, except by 

submarines.273

The MO Carrier Force had been tasked to ferry eighteen Zero fighter aircraft 

from Truk to Rabaul, flying them off on 2 May. Unforeseen events caused this 

simple task to disrupt the timetable for the entire operation.274 Everything went 

according to plan until the 2nd, when the force reached a position about 240 miles 

northeast of Rabaul. That day and the next Takagi tried to launch Zeros but failed 

because of bad weather, which also prevented the carriers from refueling. Takagi 

then decided to refuel on the 4th and make another attempt (which was apparently 

successful) before resuming his southerly advance. The loss of two days derailed 

the meticulous synchronization of the plan.275 As it turned out, the MO Carrier 

Force could not be in a position to protect Tulagi until 5 May, too late to have any 

real impact on the situation.276

In the morning of 2 May TF 17 completed refueling from Neosho, but Fletcher was disappointed to receive a message from Fitch that TF 11 would not complete refueling until noon on 4 May. Fletcher also learned, from MacArthur’s 

dispatches, that the enemy was making final preparations for the advance on 

Port Moresby. Because his own force was too far away, he directed Fitch to fuel 

his destroyers on a northwesterly course at night and rejoin TF 17 at daylight 

on 4 May at latitude 15° south, longitude 157° east. Task Force 44 was also to 

join TF 17 at that point (see sidebar, “Allied Task Organization”).277 Task Forces 

17 and 11 steamed at low speed while being refueled. Their tracks crossed and 
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recrossed in the forty-five-by-sixty-mile general area. These maneuvers were 

dangerous, because the Coral Sea was known to be the operating area of the 

enemy submarines.278

On 2 May, the Allied cryptanalysts deduced that two heavy cruisers (Atago and 

Takao) were to arrive at Rabaul at 0800 on 3 May. They also learned that the enemy 

was planning an offensive action against Ocean Island.279 They believed too that 

because of bad weather, the ferrying of ten aircraft to “RR” (Rabaul) had been postponed until 3 May. Enemy messages also revealed that CarDiv 5, after the aircraft 

had been ferried ashore, would refuel at the first supply point and arrive on 7 May 

at a position of about fifty miles from an unidentified island.280 Allied analysts also 

decoded a message stating the Japanese objective of the “East New Guinea campaign” as the “destruction of the enemy forces in the area and reduction and occupation of air bases.” They also knew that the enemy forces operating in the New 

Britain area included CruDiv 5, CarDiv 5, “Ryukaku,” and Kamikawa Maru. They 

knew that enemy aircraft had been directed to search in the sector 80° to 120° from 

Rabaul and out to seven hundred miles. However, the analysts falsely reported that 

“heavy raids will be made upon Townsville and Cooktown.”281

At about 0800 on 3 May, the Japanese forces landed at Tulagi. The MO Support 

Force set up a direct screen, while the MO Main Force provided distant cover for 

the Tulagi Invasion Force. By dawn on 3 May, the MO Main Force was about 180 

miles west of Tulagi. Aircraft from Shōhō supported the invasion there. However, 

Gotō was unable to stay in the area long, because he had to support the MO Invasion Force.282 Hence, his force departed at about 1100 the same day on a northwesterly course toward Queen Caroline Harbor, on Buka Island, for refueling. The MO 

Support Force was about sixty miles west of the MO Main Force, on its way to join 

the MO Invasion Force, then preparing to leave Rabaul. The MO Carrier Force was 

about 210 miles northeast of New Ireland and about 630 miles northwest of Tulagi, 

on a southeasterly course.283

At about 0800 on 3 May, TF 17 was at 16° 43′ south, 159° 24′ east (or about five 

hundred miles south from Tulagi), sailing on a northwesterly course, while TF 11 

was at 16° 26′ south, 161° 50′ east, on a westerly heading. The distance between these 

two forces was about a hundred miles. Fletcher for some reason did not think it necessary to combine TF 17 and TF 11 into a single force. This is somewhat surprising, 

because Nimitz had directed him to combine them—at Point Buttercup, some 320 

miles south of San Cristobal Island. Fletcher had received information that the enemy would probably start his operation by 28 April, and he knew about the presence 

of CarDiv 5 at Truk. He should have also assumed that the enemy’s highest priority 

would be to cover his landings with air and surface forces. With TF 11 and TF 17 as 

a single force, Fletcher could have delivered a much more powerful attack against 

the Japanese force that landed in Tulagi. Task Force 11 had completed refueling early 
and was ready for action, but that was apparently unknown to Fletcher. The two 

forces were beyond visual distance, and it was not desirable to break radio silence.284

At 1900 on 3 May Fletcher received a message from MacArthur, who informed 

him of the presence of five or six enemy ships at 1700 on 2 May off the southern 

tip of Santa Isabel Island, possibly moving toward Tulagi. MacArthur also stated 

that two enemy transports had been sighted at Tulagi unloading onto barges, at an 

“unspecified time.” Fletcher now regretted that the entire force was not combined 

and able to deliver a powerful strike at daylight the next day. Fletcher directed 

Neosho with one destroyer to proceed to latitude 15° 00′ south, longitude 157° 00′

east to meet TF 11 and Crace’s group at about 0800 on 4 May. Afterward, those 

forces would steam eastward and join TF 17 at latitude 15° 00′ south, longitude 

160° 00′ east at daylight on the 5th.285

Allied radio intercepts at this time revealed Inoue’s orders to subordinate forces. 

In a message decoded on 3 May, Inoue directed that “if the enemy (Carrier) Striking Force is determined to be in . . . the MO Striking Force will operate as follows: 

Pass [north-northeast?] of RX, thence south; at 0600 on 5 May, after arrival . . . 

proceed in accordance with further orders; if no further orders received, proceed to 

RXB. If plane search is required in southern and . . . sectors ComCarDiv 5 will send 

carrier bombers to RXB at dawn. . . . will proceed to RXB after taking stores.” The 

cryptanalysts believed that “RX” referred to Bougainville and “RXB” to Tulagi.286

Phase II (4–7 May)

This phase of the operation began with an Allied carrier attack on Tulagi on 4 May. 

For the next three days the opposing carrier forces tried to locate each other. They 

misidentified ships they sighted, and that led to strikes against unintended targets. 

However, by the end of 7 May each side knew the location of the other and was 

prepared for the decisive carrier engagement the next day.

The Japanese landing at Tulagi on 3–4 May was unopposed. Three seaplane tenders arrived to Tulagi from Santa Isabel on the night of 3 May. The Support Force 

provided a direct screen, while Gotō’s MO Main Force provided distant cover. By 

dawn on the 3rd these forces were positioned about 180 miles west of Tulagi. From 

that position, about twenty aircraft from Shōhō supported the Tulagi Invasion 

Force until, as noted, Gotō had to move away to support the MO Invasion Force.287

The MO Invasion Force, escorted by one light cruiser and six destroyers, left 

Rabaul on 4 May and sailed southward. It planned to transit the Jomard Passage 

around midnight on 6–7 May and sail around the tip of Papua New Guinea toward Port Moresby.288 Both the MO Main Force and the MO Support Force having 

withdrawn, the Tulagi Invasion Force was left without cover. Yet this seemed to the 

Japanese to pose no immediate danger, because they expected no enemy reaction 

to their landing at Tulagi. In any case, CarDiv 5 was supposed to be about 120 miles 

north of Tulagi and from there would be able to cover it. Unfortunately for the 
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Japanese, Takagi’s force, having been delayed ferrying Zeros to Rabaul, was actually 

340 miles north.289

On 4 May at about 0630, from a position of some 150 miles southwest of the 

island, Yorktown launched the first of three strikes against the enemy ships at Tulagi 

and positions ashore. The first-wave attack was delivered between 0815 and 0830. 

By about 0900, TF 11 and TF 44 were joined, about 250 miles south of TF 17.290 Yorktown’s second wave was conducted between 1210 and 1410 and the third between 

1500 and 1515.291 Some sixty aircraft in all took part in these strikes. Despite a large 

number of bombs and torpedoes dropped, the results were disappointing. Only 

a single enemy destroyer, one auxiliary, and two special-duty minesweepers were 

sunk; four other ships were damaged.292 The remaining enemy transports and minelayers and one destroyer immediately left the Tulagi harbor.293 The Japanese lost five 

seaplanes, while the Allies suffered three aircraft lost and eight others damaged.294

The Japanese continued to build their seaplane base, which became operational on 

6 May and conducted its first reconnaissance flights.295

The MO Carrier Force was refueling about 350 nautical miles north of Tulagi when 

a report of the enemy attack was received by Takagi. He stopped the refueling and 

directed his force to sail southeast and search for the enemy carriers in the Solomons 

area. These searches were unsuccessful. The Japanese were greatly surprised by the attack on Tulagi. Until then they had firmly believed that the enemy would be forced to 

react to their moves; they now learned that the situation was the other way around.296

MacArthur transmitted during the execution phase of the operation a number of 

reports to Fletcher on the type, positions, and movements of enemy forces, including those he was likely to encounter at Port Moresby. MacArthur also summarized 

enemy activity at Tulagi, Savo, and Guadalcanal, and west of Bougainville, on the 

basis of aerial reconnaissance.297 Because of the poor training of the pilots and inadequate number of aircraft, however, searches by SWPA’s land-based aviation were 

unsuccessful in locating the enemy forces on 5 and 6 May.298

On 4 May, a message was received from FRUMEL outlining the Japanese timeline for the MO Operation. It was similar in content to the message decoded by the 

U.S. analysts on 3 May. The difference was that FRUMEL’s message stated that the 

MO Striking Force (carriers) would be on X–3 (7 May) southeast of Port Moresby 

and would launch attacks in the Moresby area.299

On 5 May Nimitz informed Fletcher and Fitch that there were reliable reports 

as of 3 May that the “Orange [i.e., Japanese] Moresby Striking Force composed of 

CruDiv 5 and CarDiv 5 will launch attacks on the Allied bases Port Moresby areas 

on X-Ray minus three, or minus two, days. These attacks will be launched from the 

southeast. X-Ray day is not known but one indication points to 10 May as X-Ray 

day. Above attacks to be carried out until successful completion by Orange.”300 The 

Allied commanders also learned that the MO Carrier Force would be joined by the 
Tulagi Invasion Force at 1400 on 6 May. The combined formation would leave the 

Coral Sea at about 1800 on 7 May and steam south of Emerald Reef, in Milne Bay.301

After receiving this message, Fletcher decided to start refueling, move toward the 

Louisiades the next day, and fight a carrier engagement on the 7th.302 Both of Fletcher’s carrier groups sailed on a westerly course; Crace’s TF 44 was about fifty miles 

ahead. In the meantime, Takagi’s force turned northwest, passed Rennell Island, and 

sailed toward Guadalcanal. Gotō’s force began to refuel in the Solomon Sea south 

of Bougainville. Neither the Japanese nor the Allied commander knew about the 

other’s presence.303

On 5 May, Allied intelligence reported that the Japanese might land at Port 

Moresby between 5 and 10 May. SWPA B-17 and B-26 bombers were put on alert.304 

MacArthur’s headquarters also published a translated intercept supporting the 

strong probability that the carrier and its escorts were part of the “occupation force.” 

On 5 May, an intercepted radio message gave a location for the MO Invasion Force 

identical to the one mentioned in aerial reconnaissance reports. MacArthur sent to 

Fletcher and Nimitz a translated intercept from FRUMEL that at 0600 on 5 May the 

MO Invasion Force would be at latitude 8° south, longitude 155° east at a speed of 

twenty-three knots on course 300°. It would leave the Solomon Sea before 7–8 May, 

after the Tulagi force joined it.305

The ships of TF 17, on southwesterly courses, were refueled by Neosho on 5 and 

6 May. At 0735 on the 6th, Fletcher put his Operation Order No. 2-42 in effect.306

His task organization combined Task Forces 17, 11, and 44 into an enlarged TF 17, 

which now consisted of two large carriers with 116 aircraft, seven heavy cruisers, 

one light cruiser, thirteen destroyers, two fleet tankers, and a seaplane tender. Tactically, it was divided into five groups (see sidebar, “Allied Task Organization”).307 Task 

Group (TG) 17.2 had a dual mission of operating against the Japanese force advancing southward and protecting the carriers against air and submarine attacks. The 

main task of TG 17.3 was to defend the carriers. These two groups were so organized 

that they could, depending on the situation, carry out each other’s missions. Fletcher 

believed that four destroyers screening each carrier provided sufficient protection.308

Because he was senior to Fletcher and the more experienced aviator, Fitch became 

officer in tactical control of all air operations. The enlarged TF 17 would operate 

generally in the Coral Sea, about seven hundred miles south of Rabaul, outside the 

range of Japanese land-based aircraft.309

On 6 May Kamikawa Maru, one of the two seaplane tenders of the Support Force, 

was detached at Deboyne Island to establish a seaplane base. That base became operational the next day. Afterward, the rest of the Support Force was to withdraw 

north-northeast near D’Entrecasteaux Island to protect the right flank of the MO 

Invasion Force.310

Continued on page 59
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Allied Task Organization

POA Forces

(Adm. Chester W. Nimitz, CINCPac, Pearl Harbor)

Task Force 17

(Rear Adm. Frank Jack Fletcher, Yorktown)

TG 17.2 (Attack Group, Rear Adm. Thomas C. Kinkaid)

TU 17.2.1 (2 CAs—Minneapolis, New Orleans)

TU 17.2.2 (3 CAs—Astoria, Chester, CA 33 Portland)

TU 17.2.4 (5 DDs—Phelps, Dewey, Farragut, Aylwyn, Monaghan)

TG 17.3 (Support Group, Rear Adm. John G. Crace)

17.3.1 (2 CAs—HMAS Australia, Chicago; 1 CL—HMAS Hobart)

17.3.4 (2 DDs—Perkins, Walke)

TG 17.5 (Air Group, Rear Adm. Aubrey W. Fitch)

TU 17.5.1 (2 CVs—Yorktown, Lexington)

(Yorktown—17 F4F Wildcat fighters, 18 SBD-2 Dauntless dive-bombers, 13 TBD-1 Devastator 

torpedo bombers)

(Lexington—21 F4F Wildcat fighters, 18 SBD-2 Dauntless dive-bombers, 17 SBD-2 Dauntless 

dive-bombers [scouts], 12 TBD-1 Devastator torpedo bombers)

TU 17.5.4 (4 DDs—Morris, Anderson, Hamman, Russell)

TG 17.6 (Fueling Group)

2 AOs (Neosho, Tippecanoe)

2 DDs (Sims, Worden)

TG 17.9 (Search Group)

1 AV (Tangier)

VP-71 (6 PBY-5s) 

VP-72 (6 PBY-5s) 

SWPA Forces

(Gen. Douglas MacArthur, Brisbane)

Allied Naval Forces 

(Vice Adm. Herbert F. Leary)

TF 42 Eastern Australia Submarine Group

(Rear Adm. Francis W. Rockwell)

Task Group 42.1 (Capt. Ralph Waldo Christie) 

1 AS (Griffin, at Brisbane)

SubDiv 53 (S-44, S-45, S-46, S-47)

SubDiv 201 (S-37, S-38, S-39, S-40, S-41)

TF 44 

(Rear Adm. John G. Crace, RN; temporarily assigned to TF 17)

1 CA (HMAS Australia)

1 CL (HMAS Hobart)

Allied Air Forces 

(Lt. Gen. George H. Brett, Melbourne)

3rd Bombardment Group (light) (Charters Towers) 52 bombers (19 B-25s, 19 A-24s, 14 A-20s)

8th Light Bombardment Squadron 

13th Light Bombardment Squadron 

90th Light Bombardment Squadron 

22nd Bombardment Group (medium) (Townsville Area) 92 bombers (12 B-25s, 80 B-26s)

90th Light Bombardment Squadron 

13th Light Bombardment Squadron 

19th Bombardment Group (heavy) (Cloncurry) 48 B-17s 

30th Bombardment Squadron

40th Reconnaissance Squadron

93rd Bombardment Squadron 

435th Bombardment Squadron

8th Pursuit Group (Townsville Area, Port Moresby) 100 fighters (50 P-39s each)

35th Fighter Squadron 

36th Fighter Squadron 
In the early morning of the 6th Takagi’s carrier force was about 120 miles southwest of the western tip of Guadalcanal. At that point a flying boat from Tulagi 

detected the U.S. task force and accurately reported its position. Headquarters in 

Rabaul received the report and relayed it to Takagi. Allied cryptanalysts picked up 

the signal;311 Takagi, however, would not receive this information until 7 May.312 

Meanwhile, also on the 6th, Takagi started refueling his ships about 180 nautical 

miles west of Tulagi in preparation for a carrier engagement the next day. Gotō’s 

MO Main Force was south of Bougainville and about five hundred miles to the 

northwest of TF 17.313

At 0735, four U.S. B-17 heavy bombers from Port Moresby detected the MO 

Main Force some twenty-five miles east of Misima Island, in the Louisiades. At 

that time the enemy transports were seventy to a hundred miles to the northwest 

of other forces.314 The U.S. bombers attacked but inflicted no damage. The MO 

35th Pursuit Group (Sydney) 100 fighters (P-39s/P-38s) 

49th Pursuit Group (Darwin) 90 fighters (P-40s) 

7th Fighter Squadron 

8th Fighter Squadron

9th Fighter Squadron 

Photographic Squadron; 4 aircraft Flight A, 8th Bombardment Squadron

Royal Australian Air Force

No. 11/20 Squadrons (Gavutu-Tanambogo, Tulagi) 4 PBY-5 Catalinas (withdrawn on 2 May 1942)

No. 24 Squadron (Townsville) 3 Wirraways (trainers used as fighters)

No. 32 Squadron (Port Moresby) Hudson bombers

No. 75 Squadron (Port Moresby) 3 P-40s

Tulagi

2/1 Independent Company, Australian Imperial Force (24 commandos)

(withdrawn on 2 May 1942)

Port Moresby 

Garrison

(Maj. Gen. B. M. Morris, some 5,000 troops) 

39th Infantry Bn.

49th Infantry Bn.

53rd Infantry Bn.

13th Field Regt.

23rd Heavy AA Battery

Detachment, 1st Independent Co.

30th Infantry Bde. Signal Section 

30th Infantry Bde. HQ Defense Platoon 

Fixed Defenses

Moresby Fixed Defenses Fortress Engineers 

Moresby Fixed Defenses AA Artillery (six 3-inch guns)

1st Army Troops Co. 

7th Field Co. 

New Guinea Volunteer Rifles

Papuan Infantry Bn.

8th Military District Section Intelligence Corps 

15th Supply Personnel Co. 

Base Hospital 

Sources: Bates et al., Battle of the Coral Sea, app. 2, table 1; Coulthard-Clark, ”RAN and RAAF Involvement in the Battle of 

the Coral Sea,” p. 66.
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Invasion Force was detected by three B-17s at 1300, heading for the Jomard Passage. Inoue knew that at least two of his ship groups had been detected. However, 

he was certain that the Americans had not detected the MO Carrier Force.315 At 

0810 Japanese search aircraft reported sighting what seemed a large enemy force 

about 485 miles south of Rabaul.316

At about 1000, a reconnaissance flying boat from Tulagi detected TF 17. Takagi 

received that report about 1050, when his force was about three hundred nautical 

miles north of TF 17, still refueling. He sent both carriers, accompanied by two 

destroyers, southward at twenty knots to reduce the distance to the enemy carrier 

force. According to Japanese reports, Takagi believed that the chance to attack the 

enemy carrier force had been lost and turned north at 1800 to await another opportunity to attack during the following day.317 At that point the presence of Takagi’s 

force some seventy miles north of TF 17 was unknown to Fletcher. The Japanese 

carriers were shielded by the overcast of a cold front, and search aircraft did not 

detect them. Takagi, for his part, failed to carry out long-range searches on either 

5 or 6 May.318

At about 1030 four B-17s from Cloncurry, staged through Port Moresby, unsuccessfully attacked Shōhō some sixty miles south of Bougainville. At around 1300, 

Allied search aircraft detected the MO Invasion Force sailing southward toward 

the Jomard Passage.319 By midnight on 6–7 May, the MO Invasion Force was northward of Misima Island; the MO Main Force, with Shōhō, was some ninety miles 

northeast of Deboyne Island.320 Not until the afternoon of 6 May did Fletcher get 

a reliable picture of the situation: the MO Invasion Force would come through the 

Jomard Passage between Misima and Tagula Islands, off the tail of New Guinea, on 

7 or 8 May. The MO Carrier Force was about 350 miles to the southeast searching 

for the enemy carrier force.321

At 0625 on 7 May, TF 17 was about 115 nautical miles south of Rossel. Fletcher 

would write in his postaction report that he had planned to use the morning air 

search on the 7th to locate the most suitable objective for attack and to obtain positive or negative information regarding enemy carriers, on which he had obtained 

nothing since the previous afternoon. However, searches to the east and northeastward were not completed, owing to bad weather.322

During the night of 6 May, Fletcher had received reports from SWPA landbased aircraft of enemy transports and light cruisers heading toward the Jomard 

Passage. For this reason he directed at 0645 on 7 May that Crace’s TG 17.3, plus 

the destroyer Farragut, proceed northward and block the passage.323 As TG 17.3 

approached, a Japanese seaplane detected it, mistakenly reporting “one battleship, 

two heavy cruisers and three destroyers.” At about 1430, TG 17.3 was attacked by 

twelve torpedo bombers and nineteen land-attack aircraft from Rabaul. All these attacks were skillfully avoided by the Allied ships.324 Crace’s force was also mistakenly 
attacked by three high-level B-17 heavy bombers, but all their bombs fortunately 

missed their intended targets.325

At 1526, Crace reported to Fletcher that he was unable to complete his mission 

without air cover and would withdraw to a position some 220 miles southeast of 

Port Moresby. From there TG 17.3 would be able to intercept any enemy force exiting the Louisiades and advancing toward Port Moresby. TG 17.3’s ships, however, 

were low on fuel. Crace also did not have information on the location of TF 17 

or know Fletcher’s intentions. Nonetheless, because of TG 17.3’s presence Inoue 

ordered the invasion convoy to loiter north of the Jomard Passage and await the 

outcome of the pending carrier battle.326

Fletcher had been well aware that Crace would be operating without air cover, 

but he intended that the enemy convoy not slip through the Jomard Passage and 

reach Port Moresby. Fletcher later explained that he had sent Crace north to ensure 

that the invasion was thwarted even if the enemy carriers finished off TF 17 in the 

expected duel.327 Fletcher would also claim, in an interview after the war, that he 

“feared the opposing carriers would quickly neutralize each other,” recalling the 

examples of “many prewar tactical exercises.” In his view, Crace’s group would be 

able to prevent the enemy invasion force from exiting the Jomard Passage whether 

the Allied carriers intervened or not.328

Nonetheless, Fletcher made a wrong decision in detaching TG 17.3. It was too 

risky to employ a surface force without air cover in an area known to be within effective range of enemy land-based aircraft. It was pure luck (notwithstanding the 

skill of his ships) that Crace’s force was not seriously damaged or destroyed; Fletcher 

had had no way of knowing what would happen. Also, by detaching Crace’s force 

Fletcher seriously weakened the antiair and antisubmarine defense of his carriers, 

which were, in today’s terms, the “friendly operational center of gravity.” With the 

detachment of an additional destroyer during the night of 7–8 May, TF 17 was left 

with twelve instead of nineteen escorts for the decisive engagement that occurred 

on the 8th.329 Had TF 17’s carriers been destroyed, the enemy would have had no 

difficulty destroying TG 17.3 as well.

In the morning on the 7th, Takagi still did not know the whereabouts of any 

enemy carrier force. He made a decision, based on Admiral Hara’s recommendation, to search southward to make sure that no enemy carrier force was in his 

rear as he moved westward to provide cover for the MO Invasion Force.330 Both 

land-based and carrier-based Japanese search aircraft misidentified enemy ships 

on several occasions that morning. For example, at 0522 a land-based aircraft reported the presence of one enemy carrier about 460 miles southwest of Tulagi. At 

0640, a seaplane reported “one battleship, one cruiser, seven destroyers, and what 

looks like one aircraft carrier” about ninety-five miles south of Rossel Island.331 At 

0722, an aircraft from Shōkaku reported enemy ships about 160 miles away; this 
J

was actually TG 17.6, the Fueling Group, Neosho and the destroyer Sims, misidentified as one cruiser and three destroyers. At 0800, without waiting to confirm the 

accuracy of the report, Hara launched against it seventy-eight aircraft (eighteen 

fighters, thirty-six dive-bombers, and twenty-four torpedo bombers). At 0915, 

they sighted Neosho and Sims and attacked, twelve torpedo bombers with fighters 

in the first wave, followed by twenty-six heavy bombers.332 At 1051 the Shōkaku

pilots realized the mistake in identification, but it was too late. Neosho was hit by 

seven bombs and was heavily damaged, later sinking; Sims was hit by three bombs 

and sank immediately. 

Fletcher believed that the enemy carrier force was somewhere north of his force 

near the Louisiades. Actually, Takagi’s force was about three hundred miles east of 

TF 17. At 0619 Fletcher directed Yorktown to launch ten dive-bombers as scouts. 

About 0815, these search aircraft reported “two carriers and four heavy cruisers” 

a short distance northeast of Misima Island, or some 175 miles northwest of the 

Allied carriers. Fletcher immediately decided to launch an all-out attack against 

these ships. By 1000 ninety-three aircraft (fifty-three dive-bombers, twenty-two 

torpedo bombers, and eighteen fighters) were airborne. At that time, his carriers 

were in the weather front, hidden by overcast, while Gotō’s force, which he had 

just detected, was in broad sunlight. However, after the Allied aircraft were in the 

air it was discovered that this report had been improperly decoded: the pilot had 

actually observed only two enemy heavy cruisers and two destroyers, in addition to 

the reported carrier.333 The attack groups from both Yorktown and Lexington were 

directed to attack what proved to be Shōhō.

334

At 1140 Shōhō, defended by only eight fighters and surrounded by cruisers, was attacked by Allied aircraft from both carriers.335 Shōhō was hit with seventeen bombs and five torpedoes. It sank at 1235. Fifteen out of its twenty-one 

aircraft went down with it; 638 men were killed and seventy-three wounded—

Japanese destroyers rescued about a hundred men. The Allies lost only three aircraft.336 Despite the success in sinking Shōhō, the Allied aircraft should have attacked other ships in Gotō’s force also and thereby inflicted much higher losses, but 

they did not. Instead they returned to their carriers about 1340; within an hour all 

were rearmed and ready for action. But Fletcher was still in the dark regarding the 

whereabouts of the enemy carrier force. Even if it were sighted that afternoon, it 

would be too late to launch a successful attack. He decided to turn southwest and 

mount a strike the next day. 

At about 1240, Takagi received a report from a seaplane based at Deboyne 

Island of an enemy force some eighty miles south of Deboyne. That was Crace’s 

group. A plane from Rabaul erroneously reported at 1315 sighting an enemy force 

including “two carriers” about 115 nautical miles southwest of Deboyne. Takagi 

then turned his force to a westerly course. About 1500, he informed Inoue that the 
enemy carriers were about 430 miles west of his force. Hence, he would not be able 

to launch an all-out attack until the next day. 

Shortly after 1500, Takagi received an erroneous report from a seaplane based 

on Deboyne that the enemy carrier force (actually TG 17.3) had changed course to 

the southeast. Hence, at 1515, Hara sent eight bombers to confirm the report by 

searching two-hundred-nautical-mile sectors to the west of the Japanese carriers. 

However, before hearing from them, Hara made a hasty and unsound decision to 

launch an attack on the supposed enemy carrier group; at 1615 he sent twelve divebombers and fifteen torpedo bombers with his most experienced pilots and crews 

to search westward out to 280 miles. In the meantime the first group of aircraft 

returned without having found the enemy ships. At 1747 Yorktown’s radar detected 

the second group; at that time the Japanese carriers were some two hundred miles 

east of TF 17. Yorktown’s eleven fighters were vectored to intercept the incoming 

Japanese aircraft. In the ensuing dogfights, several enemy aircraft were shot down 

and one was damaged, while the Allies lost three. The Japanese pilots now became 

disoriented; at about 1900, six of them tried to land on Yorktown, mistaking it for 

their own carrier until they encountered AA fire and turned away. In addition, 

eleven aircraft were lost trying to make night landings on the Japanese carriers.337 

Only sixteen out of twenty-seven aircraft made it back to their decks.338 By 2000 on 

7 May, when the last Japanese aircraft landed, the opposing carrier forces were only 

about a hundred nautical miles apart.

Phase III (8–11 May)

The two opposing carrier forces did not detect each other until the morning of 8 

May. At about 0615, the Japanese carrier force was about 140 miles east of Rossel 

Island. Hara launched seven torpedo bombers to search from southeast to southwest out to 250 miles; several aircraft from Rabaul and Tulagi assisted. CarDiv 5’s 

screen was reinforced by two heavy cruisers from Gotō’s force. The MO Invasion 

Force was directed to steam to a position forty miles east of Woodlark Island and 

await the outcome of the coming battle. At that time TF 17 was some 180 nautical 

miles southeast of the Louisiades. 

At 0635, Fitch launched eighteen bombers to search in all directions out to 

about two hundred nautical miles. The Allied carriers were under mostly clear 

skies; visibility was about seventeen miles. In contrast, the enemy carriers were 

now under a warm frontal zone, with low-hanging clouds and heavy overcast; visibility varied from two to fifteen miles. Nonetheless, Lexington’s aircraft sighted the 

enemy carriers at about 0820, and a few minutes later the Japanese aircraft spotted 

the American ones. The opposing carriers were then about 210 nautical miles from 

each other. The two sides were almost even in strength; the Allied carriers had 116 

aircraft (118 were operational), while the Japanese had 121. The Japanese carriers 
J

had a screen of four heavy cruisers and six destroyers, while the American carriers 

had five heavy cruisers and seven destroyers.

Between 0822 and 0915, the Japanese carriers launched a combined strike group 

of sixty-nine aircraft (eighteen fighters, thirty-three dive-bombers, and eighteen 

torpedo bombers). In contrast, the Allied carriers launched their strikes separately. 

From 0840 through 0915, Yorktown sent forty-one aircraft, and all but four reached 

their targets. Lexington launched within the same time frame forty-three aircraft, 

but only twenty-one reached their targets.339 Yorktown’s dive-bombers arrived first 

over the Japanese carriers but had to wait for the torpedo bombers. Shōkaku and 

Zuikaku were about ten thousand yards apart, hidden under a rainsquall and protected by about sixteen fighters. Yorktown’s aircraft did not find Zuikaku and so focused all their attention on Shōkaku, attacking at 1100. The torpedo bombers failed 

to achieve any hits.340 Yorktown’s dive-bombers obtained only two bomb hits;341

however, one of them rendered Shōkaku unable to launch aircraft. Lexington’s aircraft arrived over their targets at 1130; two dive-bombers attacked Shōkaku and 

scored one hit; two other dive-bombers attacked Zuikaku but missed.342

In the meantime, at 1044, the Japanese aircraft attacked the Allied carriers. 

Lexington’s radar detected the enemy aircraft at a range of about seventy miles, and 

nine fighters were sent to intercept. However, six of them flew too low and missed 

the enemy aircraft. The Allied carriers were about three thousand yards apart. At 

1113 the Japanese started their attack, giving most of their attention to Lexington.

Yorktown received one bomb hit, and Lexington was struck by two torpedoes and 

two bombs.343 Lexington was heavily damaged and unsalvageable; it was sunk by a 

destroyer that evening to prevent it from falling into enemy hands. Nimitz in his 

action report noted that in contrast to the attacks with entire squadrons the Americans practiced, in the Coral Sea the enemy squadrons broke up into small groups 

that attacked from multiple directions.344 After the engagement the Allied carriers 

were left with at least forty-nine operational aircraft, while the Japanese had only 

thirty-nine available to fight the next day.345

Takagi mistakenly believed that both enemy carriers were sinking and so decided in the early afternoon that he could send the damaged Shōkaku back to Truk.346 

He was not entirely wrong in doing so. As Takagi and Hara informed Inoue, they 

were unable to launch a second strike that afternoon, or probably the next day either, for reasons of low aircraft strength, pilot fatigue, and low fuel in the screening 

ships. Because of the repeated interruptions between 4 and 8 May, the MO Carrier 

Force had never fully refueled; some destroyers had only 20 percent of their fuel 

capacity remaining, the rest of them 40 percent.347

In late afternoon on 8 May, Inoue and his staff made a detailed estimate of the 

situation. Only Zuikaku was left undamaged, and it had only half its aircraft. In his 

view, the enemy had lost one carrier and probably another. The question for Inoue 
was whether the MO Invasion Force could proceed to Port Moresby. He believed 

that a single weakened carrier air group was incapable of protecting it from the 

land-based aircraft in Australia. Also, the Japanese forces needed to regroup. Inoue 

decided to delay the attack on Port Moresby until 3 July. Hence, Inoue directed the 

MO Invasion Force to return to Rabaul. He also decided to hold Tulagi but to abandon the seaplane base at Deboyne as untenable for the time being.348

Inoue’s decision greatly angered Yamamoto, who was convinced that the Japanese had sunk two enemy carriers and won the battle. Yamamoto, who did not 

know that the Japanese carriers had few aircraft remaining, saw no reason why the 

operation should not continue. He could do nothing about the postponement of 

the landing at Port Moresby, but he did not want the enemy naval forces to escape; 

he ordered Inoue to resume his pursuit and “annihilate the remaining enemy force.” 

At about 2300 on 8 May, Inoue directed Takagi and Gotō to resume their attack. 

At 0200 the next day, Zuikaku and its escorts changed course to the southeast and 

then southwest. About one hour later Gotō’s force was joined by Zuikaku’s group. 

Shortly afterward, Inoue changed his mind again and directed both groups to reverse course and head northward. On 11 May, Takagi received orders to leave the 

area entirely.349 The Port Moresby–Solomons operation was over.

Aftermath and Assessment

After the loss of Lexington, TF 17 sailed southward to regroup. On the morning of 

9 May a scout plane from Yorktown sighted the enemy carrier force 175 miles to 

the northwest. Fletcher prepared his force for possible attack and launched a strike. 

He also asked for help from SWPA air forces. Brett responded by sending fourteen 

bombers, which reached the target at the same time as the Yorktown group. However, the target proved to be a reef. That afternoon Nimitz directed Fletcher to return to Pearl Harbor or the West Coast with both carriers (Nimitz had not yet been 

informed of the loss of Lexington) and the screening ships of the original TF 17. 

Kinkaid’s TG 17.2 would join TF 16. The same day, Fletcher detached Crace’s force 

and brought TF 44 back into existence. Task Force 44 then proceeded to Brisbane 

for refueling.350

The Allied cryptanalysts learned on 9 May that the enemy MO Carrier Force 

south of the Solomons included CarDiv 5, CruDiv 5, CruDiv 18, and CruDiv 6; 

Gunboat Division 8 was also in the area with landing and occupation forces; “Ryukaku” might also be in the New Britain area. They also learned that Zuikaku and 

Shōkaku were damaged and withdrawing northward.351

On 10 May, Fletcher sent a message informing Nimitz that he planned to stop 

at Tongatabu on the way to Pearl Harbor.352 Also on 10 May, the Allies learned from 

reading enemy messages that the Port Moresby operation had been postponed, 

that the occupation force would return to Rabaul, and that CruDiv 5 and CarDiv 

5 would refuel in the Bougainville area and then cover the occupation of Ocean 
J

and Nauru Islands. CruDiv 6, with two heavy cruisers of the Aoba class, plus gunboats and destroyers, would support the Nauru-Ocean invasion.353 Fletcher did not 

respond to these movements. At 1600 on 11 May, Fletcher detached Kinkaid to 

Nouméa, while one heavy cruiser was to rejoin TF 17 at Tongatabu.354

On 12 May, all indications in Allied COMINT showed that the enemy bombers in the Marshalls would be moved to Rabaul, though this movement might be 

canceled as a result of the postponement of the Port Moresby offensive. Evidence 

showed that the covering force for the Nauru-Ocean occupation would consist 

of Zuikaku, two Haguros, two Aobas, and one division of destroyers as a screen. 

Zuikaku might be withdrawn to Japan because of the condition of its aircraft. Part 

of the occupation force would leave the Rabaul area around 10 May, with 14 May as 

the date for the assault on Nauru and Ocean Islands.355

Task Force 16, with Enterprise and Hornet, sailed from Pearl Harbor on 30 April 

for the Coral Sea but did not reach the scene of action in time. Instead, it made a 

feint toward Nauru and Ocean Island. On 15 May, Inoue received a report from 

search aircraft of the presence of enemy carriers some 450 miles east of Tulagi. 

Shortly afterward, he directed the Nauru-Ocean Island Invasion Force to return to 

Truk (the two islands were eventually captured by the Japanese, on 25–26 August 

1942).356 On 16 May, TF 16 reversed its course toward Pearl Harbor, arriving ten 

days later. 

The battle of the Coral Sea was the first in which surface ships did not see each 

other and so had no opportunity to use their guns or torpedoes. All losses on both 

sides were caused by air strikes. The Japanese sank a fleet oiler and a destroyer 

and so heavily damaged a large carrier that it had to be sunk. The Japanese lost 

only one small carrier and a few small ships at Tulagi. They also lost sixty-nine 

aircraft (twelve fighters, twenty-seven dive-bombers, and thirty torpedo bombers) 

and 1,074 men; the Allies lost sixty-six aircraft and 543 men.357 One Japanese large 

carrier was heavily damaged, and the lost aircraft and experienced pilots were hard 

to replace; CarDiv 5 did not rejoin the fleet for more than two months.358 Nonetheless, the Japanese achieved a clear tactical victory. The operational victory, however, 

belonged to the Allies, because the Japanese attempt to capture Port Moresby by 

sea was stopped and the entire operation delayed. Further, the damage inflicted 

on Shōkaku and losses to Zuikaku’s air wing prevented both carriers from taking 

part in the Midway-Aleutians operation the next month. Had they been available 

then, the chances of Allied victory would have been much lower. After Midway, the 

Japanese decided to seize Port Moresby by land, across the Owen Stanley Range; 

that attempt ultimately failed. 

Conclusion and Operational Lessons Learned 

The Japanese strategic decision in January 1942 to expand their defensive perimeter in the aftermath of their initial successes in the Pacific War was due to what has 
been called “victory disease.” The Japanese were surprised by their quick victories 

and small losses. The leaders of the IJN were far more aggressive than those of the 

army in wishing to prevent the enemy from gaining time and mounting a counteroffensive. Yamamoto was keenly aware that decisive victory against the U.S. Pacific 

Fleet was the key to consolidating Japanese strategic success before the industrial 

power of the United States became overwhelming. In trying to expand Japan’s defensive line in the Pacific and the Indian Oceans, however, naval and army leaders 

clearly did not match their strategic ends and means. Differences between the Naval General Staff and the Combined Fleet on whether the main thrust in the Second Operational Stage of the war should be in the South, Central, or North Pacific 

resulted in a bad compromise plan. The subsequent changes in timing of the Port 

Moresby–Solomons and Midway-Aleutians operations, coupled with Yamamoto’s 

inability to assign adequate forces to either major operation, were perhaps the main 

reason that both ultimately failed. 

A major problem for the Japanese was a lack of centralized planning at the strategic level. The Army and Naval General Staffs had to negotiate their differences in 

planning any major army-navy operation. In the IJN’s case, the situation was even 

more complicated because the Combined Fleet, led by Yamamoto, exercised often 

much greater influence in operational planning than the Naval General Staff did. 

In sequencing major operations in two widely separated parts of a theater, strategic 

leadership should make sure that adequate forces are available or becoming available 

for the accomplishment of each operational objective. Also, sufficient time should be 

given for redeployment, upkeep, and rest of forces taking part in the successive major 

operation. Otherwise, the risk of ultimate failure in one or both major operations will 

be considerably increased. Planning of major operations and campaigns should be 

vested in the hands of a single operational commander; competing planning responsibilities result in a compromise plan and often lead to a failure.

In early 1942, the problem for the Americans was how to check further Japanese advances in the southern and southwestern Pacific. Admiral King was the 

most vocal proponent of the view that the Allies should strengthen their defenses 

in the South Pacific and prevent any additional gains by the Japanese; otherwise, 

he argued, it would take much more time and sacrifice to roll back the Japanese 

conquests. The Allied strategy of fighting Germany first was fundamentally sound. 

However, General Marshall and other Army leaders were too rigid in pursuing 

their Germany-first strategy. They fended off King’s efforts to deploy more troops, 

better equipped and trained, to the South Pacific. King’s strategy was vindicated 

by the eventual Allied success in protecting the links between Australia and New 

Zealand and the United States. In determining the main and secondary theaters of 

war, the strategic leadership should not go to extremes and assign almost all the besttrained and -equipped forces to the main theater; the principle of economy of effort 
J

requires that numerically sufficient and highly capable forces be assigned to the theater of secondary effort as well.

The weather played a prominent role in both the Japanese and the Allied carrier operations and greatly influenced the outcome of the engagement on the 8th. 

If the Allied carriers had been protected by low-hanging clouds and poor visibility 

as their Japanese counterparts were, the Japanese aircraft might not have been successful. Planning and preparation for a major naval operation or campaign require 

thorough study of all aspects of the operating area. Despite all technological advances, 

the weather and climate considerably affect the employment of naval forces and aircraft. Operational commanders and planners should properly evaluate their potential 

impact on all phases of a major operation or campaign. 

The Port Moresby–Solomons operation was conducted over a major part of the 

Coral Sea and the adjacent Louisiades and the Solomons Archipelago, as well as 

the southeastern part of New Guinea and the Bismarck Archipelago. Allied forces 

deployed from bases in New Caledonia, the New Hebrides, and eastern Australia. 

This part of the southwestern Pacific was militarily undeveloped, lacking naval and 

air bases and support facilities adequate for surface combatants, submarines, or aircraft. The Japanese controlled a number of well-developed naval bases and airfields 

in the Bismarcks and the Carolines and on the southeastern coast of New Guinea. 

The Bismarcks and Solomons provided many natural harbors and anchorages that 

could serve as advance bases or havens for surface ships and as seaplane bases. The 

Allies were less fortunate in that there were very few good bases and airfields in the 

South Pacific; those in eastern Australia were too far away. A major problem for 

both the Japanese and the Allies was the lack of repair facilities for aircraft carriers. Forces taking part in a major operation or campaign will have great difficulty in 

accomplishing their objectives without a well developed theaterwide infrastructure. 

Hence, whenever possible, adequate naval bases and airfields and supporting structures should be developed ahead of time, in peacetime.

Relatedly, Japanese naval forces and aircraft occupied central positions and so 

operated along relatively short, interior, and divergent lines. Their bases of operations flanked the sea routes from the U.S. west coast and the Panama Canal to 

Australia and New Zealand. The Allied base of operations in the South Pacific was 

unfavorable for the employment of naval forces and aircraft. During the operation, 

Allied carrier forces occupied a central position. In contrast, the Allied land-based 

aircraft deployed in eastern Australia and New Caledonia occupied an exterior position and operated along very long and converging lines of operation. Naval warfare is invariably aimed at obtaining, maintaining, or disputing control of particular 

oceans or seas. It cannot be conducted without access to bases or ports and airfields 

in the littorals. Such positions and their location, as opposed to enemy positions, still 
have considerable influence on the successful employment of naval forces. However, 

control of positions means little unless it is combined with the factor of force. Operational commanders and planners should not overestimate the importance and value 

of either central or exterior positions and resulting lines of operation or communications. They should try in every way to maximize the advantages and minimize the 

disadvantages of given positions for the employment of their combat forces. Yet what 

counts most is not the geography of the situation but the combat readiness, morale, 

and the skills of the operational commanders in employing their forces in combat.

Both the Japanese and the Allies had undeveloped command structures in the 

theater. The Japanese structure was highly fragmented. The parochialism of the 

two services, a major problem for the Japanese throughout the war in the Pacific, 

was particularly evident at the general-staff level. However, in the planning and 

execution of the Port Moresby–Solomons operation, the Japanese ensured unity of 

effort through unity of command. Admiral Inoue, as the Fourth Fleet commander, 

was responsible for the command and control of all navy and army forces. Yet he 

depended on the Combined Fleet for additional forces and had no influence on 

Yamamoto’s decision to change the operation’s timetable. Operational commanders 

should have sufficient organic forces to ensure that assigned objectives can be accomplished; otherwise, it is difficult to exercise mission command. Optimally, they should 

also have full command and control over all subordinate forces during planning and 

the execution of a major operation or campaign.

In contrast to the Japanese, the Allies established at least the rudiments of a 

theater or operational command organization. The Southwest Pacific Area and the 

Pacific Ocean Areas were, in modern terms, “theater-strategic commands.” Most 

combat actions were conducted within the SWPA, under MacArthur. Nimitz, as 

CINCPOA/CINCPac, had exclusive authority over the employment of Task Forces 

17 and 11. As a result, a divided theater command existed both prior to and during 

the battle of the Coral Sea. This created numerous problems in organizing comprehensive searches by land-based aircraft and in intelligence sharing. Giving operational control over TFs 17 and 11 to MacArthur was effectively impossible. Neither 

Nimitz nor King would allow the employment of carrier forces by an Army general; 

the carriers were the only major striking force left in the Pacific Fleet and could not 

be put at risk. Another problem was the lack of an intermediate command level for 

the South Pacific. Nimitz, some four thousand miles from the scene of action, was 

unable to form an accurate and timely picture of the situation in the South Pacific. 

Optimally, in planning and execution of a major operation or campaign, all subordinate forces should be controlled by a single commander. This would ensure the most 

effective control over operational intelligence, fires, logistics, and protection. Theaterstrategic commanders should delegate authority to subordinate theater commanders. 
J

Boundaries between the adjacent theaters should not be so rigid as to prevent friendly 

forces from crossing them as needed. 

During the preliminaries, Nimitz employed carrier forces to great effect in reacting to Japanese advances in the Bismarcks and on the eastern coast of New Guinea. 

The Allied carrier raids in the southwest Pacific had a much greater effect on Japanese 

planning for the pending Port Moresby–Solomons operation than was realized at the 

time. The carrier raid on Tokyo on 18 April 1942 had a great psychological effect on 

the Japanese strategic leadership and people, and it reinforced Yamamoto’s decision to 

go ahead with his planned Midway operation. However, the raid deprived the Allies of 

two large carriers at a time when Admiral King had reliable information from decoded enemy messages about the acceleration of the attack on Port Moresby. Had the Tokyo raid not taken place, Nimitz would have had four carriers to oppose the Japanese 

thrust toward Port Moresby and probably would have inflicted much greater enemy 

losses. The highest strategic leadership should give to subordinate theater commanders 

full command authority over all forces deployed within their area of responsibility. Normally, the majority of one’s striking forces should be employed in the theater of main effort. Hence, these forces should not be employed in a secondary theater, thereby making it 

difficult or even impossible to reinforce the main effort in a timely way. This is especially 

true if one has timely and reliable knowledge of the enemy’s plans and intentions. Also, 

the time between consecutive operations in separate maritime theaters of operations 

should allow timely redeployment of forces from one theater to another. This, in turn, 

requires sound balancing of the operational factors of space, time, and force versus an 

operational/strategic objective. 

The Japanese had inadequate knowledge of the situation in the theater. They knew 

nothing of the enemy’s plans or intentions, because of their inability to break Allied codes and their lack of human intelligence sources. Most of their information 

was obtained by scout aircraft and seaplanes based in the Bismarcks–New Guinea–

Solomons area. Their information on the physical features of the objective area and 

on ground defenses and air strength in the southwest Pacific was accurate, but their 

knowledge of enemy carriers—their numbers, whereabouts, and movements—was a 

different matter. Apparently, the Japanese commanders and their staffs had too much 

faith in the reports of their pilots and submariners.

The Japanese seem to have based their decisions and plans on what they assessed 

as the enemy’s intentions and gave insufficient weight to the enemy’s capabilities. 

Generally, and unless the commander possesses reliable and accurate knowledge of the 

enemy’s plans, it is unwise to prepare estimates and make decisions on the basis of enemy intentions instead of his capabilities. The enemy can use deception to hide his true 

intentions and actions. 

Japanese planning for the Port Moresby–Solomons operation was deeply 

flawed. First, the plan was based on overly optimistic assumptions. The absence 
of accurate and reliable information on the whereabouts of the Allied carriers 

did not lead Inoue and his staff to assume the possibility of large enemy forces 

being present in the Coral Sea—to the contrary. The Japanese had a penchant 

for assigning multiple objectives to be accomplished simultaneously or nearly 

so. In this instance, the Japanese tried to accomplish all their objectives in a single major combat phase; they put too much emphasis on speed of action. They 

also added such minor tasks as ferrying Zeros to Rabaul without taking into account the extra time they might take. Operational commanders should not draft 

plans based on either overly optimistic or overly pessimistic assumptions. A lack 

of information on the whereabouts and the movements of the main enemy forces 

should counsel a great deal of caution in drafting operational plans. The factor of 

speed is critical for the successful employment of forces. However, a balance should 

be found between the need for speedy execution of the operation and avoidance of 

simultaneous or nearly simultaneous pursuit of multiple objectives. The mission 

given to a subordinate commander should not be changed by the addition of secondary tasks; the latter usually take more time than originally envisaged. 

The Japanese relied on the factor of surprise (and presumed enemy passivity), but they did not prepare an operational deception plan to enhance the 

chances of achieving it. Instead, they unrealistically believed that secrecy alone 

would suffice. Surprise, judiciously conceived and successfully employed, can be 

a most potent factor but should not be counted on. A plan for a major operation 

or campaign should include provision for operational deception to enhance the 

chance of surprising the enemy, but there must be means to ensure success even if 

surprise is not obtained. Secrecy alone is rarely sufficient to achieve surprise. 

The Japanese plan for the Port Moresby–Solomons operation was also overly 

complex. Its success depended heavily on precise synchronization of movements and actions of a large number of force elements, a fact that made Inoue 

reluctant to change the plan until it was too late to have any effect. No provision 

was made for unforeseen events, such as the sudden appearance of the enemy 

or his reactions, for mistakes made by the Japanese commanders, or for bad 

weather. Finally, the Japanese task organization was too fragmented. The result 

was a considerable reduction in the combat potential of the force as a whole. 

The Japanese plans could work well only if everything went according to the 

plan and the enemy reacted as envisioned. Too many intermediate objectives 

slow one’s operational tempo, and they require commitment of larger forces and 

more time for the accomplishment of the ultimate objective. They also result in 

overly complicated plans. Task organizations should be simple, straightforward, 

and logical. The principle of unity of effort through unity of command should 

be applied. Division of a force into several smaller elements should generally be 

avoided. 
J

The single greatest advantage the Allies had over the Japanese was accurate, reliable, and timely knowledge of enemy plans and intentions. The Allied commanders 

knew of the high-level Japanese debate about the Second Operational Stage of the 

war months and weeks before resulting plans were executed. King and Nimitz had 

great faith in the work of their cryptanalysts and used this tremendous advantage to 

the fullest; otherwise, they would not have been able to employ their forces so successfully. By reading and properly analyzing enemy radio messages they were able 

to concentrate and prepare TF 17 and TF 11 in the Coral Sea in time to oppose the 

advance toward Port Moresby. 

MacArthur and his staff, in contrast, apparently had little confidence in COMINT 

and instead depended on the relatively unreliable reports of land-based search aircraft based in northeastern Australia and at Port Moresby. Their information had 

only tactical value, limited by inadequate numbers of aircraft, long flying distances, 

and poor training of their crews for searches over seas and oceans. Searches by TF 

17 aircraft, for their part, were limited by divided theater command. The absence of 

searches from the Solomons was one of the main reasons why the MO Carrier Force 

was not detected prior to entering the Coral Sea. Fletcher, who was not informed 

by the SWPA of the gaps in the coverage by its aircraft, never had a full operational 

picture of the situation after the enemy forces were initially detected. In planning a 

major operation or campaign, commanders and their staffs should focus on creating an 

operational picture of all aspects of the situation in a given theater of operations. Hence 

the need to convert information obtained from strategic and tactical intelligence into 

operational intelligence; otherwise, a critically important operational perspective on the 

situation will be missing. Operational commanders should not arbitrarily decide which 

sources of intelligence are more important; all sources of intelligence should be used in 

obtaining a picture of the operational situation and its trends. 

Allied planning and preparations to counter the enemy thrust into Papua New 

Guinea started in late March 1942, when the first reliable information was obtained 

about the Japanese intentions in the southern and southwestern Pacific. The single 

major problem was how to concentrate a sufficiently potent carrier force in the Coral 

Sea. The U.S. Navy had only seven large carriers, and not all of them were available 

for action in the South Pacific. Another major problem was the shortage of oilers 

capable of underway replenishment. There was also an acute shortage of destroyers 

to screen the carrier forces and escort the transports. Fletcher’s Operation Order No. 

2-42 was a classically simple and executable plan. Nonetheless, in contrast to the Japanese, it had the Allied carriers operating separately, not as a single group. This greatly 

weakened the strike packages in combat with the enemy carrier force. Plans should be 

comprehensive but simple and logical. They should be also flexible enough to accommodate unforeseen events, due to either natural causes or the actions of commanders. Also, 

the success of a major operation at sea is heavily dependent on the logistical support 
and sustainment. Operational commanders, not logisticians, are directly responsible for 

synchronizing the operations and logistics.

The Japanese execution of the Port Moresby–Solomons operation matched the 

meticulousness, but also the rigidity, with which it had been planned. From the landing at Tulagi on 3 May until the end of the operation on 11 May, the opposing carrier 

forces made largely unsuccessful efforts to find each other, and mistaken identifications led to many minor and several major unsound decisions. Hara’s decision to 

launch a late-afternoon strike against what he believed to be an enemy carrier force 

was a reckless gamble that cost a number of hard-to-replace experienced pilots. Similarly, Fletcher’s decision to detach Crace’s TG 17.3 could have ended in the destruction of Crace’s unprotected group or greater losses for the carrier force because of 

the resulting weakening of its ship-based antiair and antisubmarine defense. Neither 

Hara’s nor Fletcher’s decision can be justified from the information each had or did 

not have at the time it was made. 

Further, and although directed by Nimitz, Fletcher ran undue risks by waiting 

until 6 May to put his operation order into effect and finally combine TF 17 and TF 

11 into an enlarged TF 17. Finally, Inoue was too slow in changing or modifying his 

plan in the face of unforeseen events, usually only after it had become obvious that 

the original plan could not be carried out. He did not display “operational vision”

—the ability to assess a situation properly, anticipate the flow of events accurately, and 

then react quickly and decisively when something unforeseen happens.

In the course of the execution of a major operation or campaign, operational commanders should keep a running estimate of the situation and make quick decisions. 

Their focus on the ultimate objective should be unwavering, but they should be willing to modify or even abandon intermediate ones. Sequencing and synchronization of 

movements should be flexible; otherwise, the plan will most likely fail. Reports from 

commanders directly involved in carrying out a task should never be exclusively relied 

on; if they cannot be cross-checked against other sources of information they should be 

treated as assumptions. As Helmuth von Moltke the Elder observed and has been often 

repeated since, no plan survives the first contact with the enemy. The enemy has a will of 

his own and will react in ways that rarely can be foreseen and that might even appear irrational. Though operational commanders and their staffs should try to obtain the best 

knowledge and understanding possible of all aspects of the situation in a theater, there 

will be always gaps, in which they must make reasoned assumptions. High-stakes risks 

must sometimes be taken, but they should be calculated—an operational commander 

must find a proper balance between overcautiousness and recklessness. Finally, friction 

can be minimized but never mastered; chance, mistakes, and pure luck are inherent to 

warfare. The knowledge, judgment, and skills of commanders and their subordinates 

therefore remain, as they have in the past, the keys to success in war. 
J

1 Steven Bullard, trans., Japanese Army Operations in 

the South Pacific Area (Canberra: Australian War 

Memorial, 2007), p. 1.

2 Louis Morton, Strategy and Command: The First 

Two Years, U.S. Army in World War II: The War in 

the Pacific (Washington, D.C.: U.S. Army Center for 

Military History, 1962; updated 1989), p. 201.

3 Toshikaze Ohmae, “The Battle of Savo Island,” in 

The Japanese Navy in World War II: In the Words of 

Former Japanese Naval Officers, ed. David C. Evans, 

2nd ed. (Annapolis, Md.: Naval Institute Press, 

1986), pp. 213–14.

4 Cited in Gary Brown and David Anderson, Invasion 

1942? Australia and the Japanese Threat, Background Paper 6 (Canberra: Parliamentary Research 

Service, 29 April 1992), p. 5.

5 John B. Lundstrom, The First South Pacific Campaign: Pacific Fleet Strategy December 1941–June 

1942 (Annapolis, Md.: Naval Institute Press, 1976), 

p. 40.

6 Brown and Anderson, Invasion 1942?, p. 6.

7 Ibid.

8 Ibid., p. 7.

9 Henry P. Frei, “Japan’s Southward Advance and Its 

Threat to Australia in the Final Stage,” cited in Mark 

Jacobsen, “US Grand Strategy and the Defence 

of Australia,” in The Battle of the Coral Sea 1942: 

Conference Proceedings, 7–10 May 1992 (Sydney: 

Australian National Maritime Museum, 1993), p. 48. 

10 Ibid., pp. 48–49. 

11 Paul S. Dull, A Battle History of the Imperial Japanese 

Navy (1941–1945) (Annapolis, Md.: Naval Institute 

Press, 1978), p. 116.

12 Ibid.

13 Lundstrom, First South Pacific Campaign, p. 42. 

14 Ibid.

15 Frei, “Japan’s Southward Advance and Its Threat to 

Australia in the Final Stage,” cited in Jacobsen, “US 

Grand Strategy and the Defence of Australia,” p. 49. 

16 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, pp. 30–31.

17 Ibid., p. 31.

18 Frei, “Japan’s Southward Advance and Its Threat to 

Australia in the Final Stage,” cited in Jacobsen, “US 

Grand Strategy and the Defence of Australia,” p. 48. 

19 Lundstrom, First South Pacific Campaign, p. 43.

20 Brown and Anderson, Invasion 1942?, p. 8.

21 “Battle of the Coral Sea: Overview and Preparations 

for Battle,” The Pacific War, pp. 5–6, www

.pacificwar.org.au/.

22 Brown and Anderson, Invasion 1942?, p. 9.

23 Lundstrom, First South Pacific Campaign, pp. 44–45.

NOTES
24 Ibid., p. 45.

25 Brown and Anderson, Invasion 1942?, annex reprinting “Battle of the Coral Sea,” Navy (April–June 

1992), p. 4. 

26 Lundstrom, First South Pacific Campaign, p. 46.

27 Ohmae, “Battle of Savo Island,” pp. 213–14; Frei, “Japan’s Southward Advance and Its Threat to Australia 

in the Final Stage,” cited in Jacobsen, “US Grand 

Strategy and the Defence of Australia,” p. 49.

28 “The US Navy Refuses to Adopt a Defensive Posture 

in the Pacific,” The Pacific War, p. 2, www.pacificwar

.org.au/.

29 Morton, Strategy and Command, p. 201.

30 Ibid. 

31 Jacobsen, “US Grand Strategy and the Defence of 

Australia,” p. 23. 

32 “US Navy Refuses to Adopt a Defensive Posture in 

the Pacific,” p. 3.

33 Lundstrom, First South Pacific Campaign, p. 92.

34 Morton, Strategy and Command, p. 204.

35 Ibid., pp. 204–205.

36 Lundstrom, First South Pacific Campaign, p. 50.

37 Jacobsen, “US Grand Strategy and the Defence of 

Australia,” p. 23.

38 Ibid., p. 49.

39 John B. Lundstrom, Black Shoe Carrier Admiral: 

Frank Jack Fletcher at Coral Sea, Midway, and 

Guadalcanal (Annapolis, Md.: Naval Institute Press, 

2006), p. 99.

40 “US Navy Refuses to Adopt a Defensive Posture in 

the Pacific,” p. 4.

41 Lundstrom, First South Pacific Campaign, p. 51.

42 “US Navy Refuses to Adopt a Defensive Posture in 

the Pacific,” p. 4.

43 Lundstrom, First South Pacific Campaign, p. 55.

44 “US Navy Refuses to Adopt a Defensive Posture in 

the Pacific,” pp. 2–3.

45 Ibid., pp. 4–5.

46 Richard Bates et al., The Battle of the Coral Sea: May 

1 to May 11 Inclusive, 1942—Strategical and Tactical 

Analysis (Newport, R.I.: Naval War College, 1947), 

p. 3.

47 Ibid., p. 4.

48 Ibid.

49 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 12.

50 Bates et al., Battle of the Coral Sea, p. 20.

51 Ibid., p. 12.

52 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 42.

53 Morton, Strategy and Command, p. 199.

54 “Battle of the Coral Sea,” p. 4.

55 Charles A. Willoughby et al., eds., Reports of General 

MacArthur: The Campaigns of MacArthur in the Pacific (Washington, D.C.: U.S. Government Printing 

Office [hereafter GPO], 1966), vol. 1, p. 46.

56 Cited in Morton, Strategy and Command, p. 199.

57 Ministry of Defence (Navy), War with Japan, vol. 2, 

Defensive Phase (London: Her Majesty’s Stationery 

Office, 1995), p. 136.

58 Bates et al., Battle of the Coral Sea, p. 22.

59 Ibid., p. 3.

60 Willoughby et al., eds., Reports of General 

MacArthur, p. 97.

61 Lundstrom, Black Shoe Carrier Admiral, p. 100.

62 Bates et al., Battle of the Coral Sea, p. 22.

63 The Fourth Fleet was reestablished on 20 October 

1937 and became subordinate to the China Area 

Fleet. On 15 November 1939, the Fourth Fleet 

became a part of the China Expeditionary Fleet; it 

became subordinate to the Combined Fleet on 15 

November 1940.

64 Bates et al., Battle of the Coral Sea, pp. 4–5. 

65 Ibid.

66 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 5.

67 Ibid., p. 52.

68 Bates et al., Battle of the Coral Sea, p. 5.

69 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 52.

70 Ibid., pp. 47–48.

71 Bates et al., Battle of the Coral Sea, p. 18.

72 Ibid.; G. Herman Gill, Royal Australian Navy, 

1942–1945 (Canberra: Australian War Memorial, 

1968), pp. 32–33.

73 Gill, Royal Australian Navy, p. 32.

74 Bates et al., Battle of the Coral Sea, p. 19; Gill, Royal 

Australian Navy, p. 32.

75 Bates et al., Battle of the Coral Sea, pp. 18–19.

76 Ibid., p. 19.

77 Ibid., pp. 18–19.

78 Ibid. 

79 Headquarters, U.S. Far East Command, Eastern New 

Guinea Invasion Operation, Japanese Monograph 

No. 96 (n.p. [Tokyo]: Military History Section, 

Special Staff, Japanese Research Division, n.d.), in 

U.S. Army Dept., War in Asia and the Pacific, vol. 5, 

The Naval Armament Program and Naval Operations

(Part II) (New York: Garland for Chief of Military 

History, 1980) [hereafter Japanese Monograph 96], 

p. 1.

80 Headquarters, U.S. Army Japan, 18th Army Operations, Japanese Monograph No. 37 (Washington, 

D.C.: Chief of Military History, n.d.), vol. 1, cited 

in Donald S. Detwiler, War in Asia and the Pacific 

1937–1949, vol. 7, The Southern Area, Part II (New 

York: Garland, 1980) [hereafter Japanese Monograph 37], p. 3. 

81 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 33. Some sources say the 

execution date was to have been 3 March.

82 Japanese Monograph 37, p. 3. 

83 Morton, Strategy and Command, p. 215.
J

84 Frederick D. Parker, A Priceless Advantage: U.S. 

Navy Communications Intelligence and the Battles of 

Coral Sea, Midway, and the Aleutians (Fort George 

G. Meade, Md.: Center for Cryptologic History, 

National Security Agency, 1993), p. 5, available at 

www.centuryinter.net/.

85 Morton, Strategy and Command, p. 215.

86 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 34.

87 Japanese Monograph 96, p. 3.

88 Morton, Strategy and Command, p. 215; Japanese 

Monograph 37, p. 3.

89 Japanese Monograph 37, p. 3.

90 Headquarters of the Commander in Chief, United 

States Fleet, Battle Experience from Pearl Harbor to 

Midway, December 1941 to June 1942: Including Makin Island Raid 17–18 August (Newport, R.I.: Naval 

War College, 15 February 1943), p. 6–1.

91 Ibid.

92 Ibid., p. 6–2.

93 Ibid. 

94 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 45.

95 Parker, Priceless Advantage, p. 6.

96 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 41; Japanese Monograph 37, 

p. 4.

97 Lundstrom, First South Pacific Campaign, p. 398.

98 Morton, Strategy and Command, pp. 214–15.

99 Lundstrom, First South Pacific Campaign, p. 398.

100 Lundstrom, Black Shoe Carrier Admiral, p. 98.

101 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, pp. 43, 54–55.

102 Ibid., p. 46. 

103 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942, folder 3222/23, box 107, Record 

Group [hereafter RG] 38, Records of the Office of 

the Chief of Naval Operations, National Archives 

and Records Administration, College Park, Md. 

[hereafter NARA].

104 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 46.

105 Ibid., p. 52.

106 Ibid., p. 48.

107 Ibid.

108 Ibid., p. 55.

109 Ibid.

110 Bates et al., Battle of the Coral Sea, pp. 5–6.

111 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 61.

112 Samuel E. Morison, History of United States Naval 

Operations in World War II, vol. 4, Coral Sea, Midway and Submarine Actions, May 1942–August 1942

(Boston: Little, Brown, 1948; repr. 1984), pp. 10–11.

113 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 61.

114 Morton, Strategy and Command, p. 237; “Notes 

by Clarke Kawakami,” folder G-15, box 9, RG 23, 

Battle Evaluation Group (BEG), Naval History and 

Heritage Command. 

115 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 4.

116 Morton, Strategy and Command, p. 235; “Interrogation of Admiral Mitsumasu Yonai,” Interrogation 

NAV No. 76, 17 November 1945, United States 

Strategic Bombing Survey (Pacific), Naval Analysis 

Division, in Interrogations of Japanese Officials

(Washington, D.C.: GPO, 1946), vol. 2, pp. 328, 330.

117 Parker, Priceless Advantage, pp. 2–3.

118 Ibid., p. 7.

119 Morton, Strategy and Command, p. 216. 

120 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 50.

121 Ibid., p. 52. Nachi, also in CruDiv 5, was not 

assigned.

122 Lundstrom, First South Pacific Campaign, pp. 46–47.

123 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 51.

124 Lundstrom, First South Pacific Campaign, p. 47.

125 Lundstrom, Black Shoe Carrier Admiral, p. 122.

126 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 52.

127 Bates et al., Battle of the Coral Sea, p. 7.

128 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 58.

129 Ibid., p. 50.

130 Ibid., p. 51.

131 Ibid., p. 58.

132 Ibid., p. 51.

133 Ibid., p. 59.

134 Ibid., p. 55.

135 Ibid., p. 49.

136 Ibid.

137 Ibid., pp. 49, 59.

138 Gill, Royal Australian Navy, pp. 40–41.

139 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 49.

140 Ibid., p. 50.

141 Lundstrom, First South Pacific Campaign, pp. 72–73.

142 Ibid., pp. 56, 59.

143 Morton, Strategy and Command, p. 217.

144 Bates et al., Battle of the Coral Sea, p. 15.

145 Ibid.

146 Lundstrom, First South Pacific Campaign, p. 73.

147 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 59.

148 Ibid., p. 60.

149 Bates et al., Battle of the Coral Sea, p. 5.

150 Ministry of Defence (Navy), War with Japan, p. 135.

151 Dull, Battle History of the Imperial Japanese Navy, 

p. 118.
152 H. P. Willmott, The Barrier and the Javelin: Japanese 

and Allied Pacific Strategies February to June 1942

(Annapolis, Md.: Naval Institute Press, 1983), p. 209.

153 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 12.

154 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, pp. 55–56.

155 Patrick H. Donovan, Oil Logistics in the Pacific War: 

In and after Pearl Harbor (Maxwell Air Force Base, 

Ala.: Air Command and Staff College, Air Univ., 

April 2001), p. 40.

156 Hiromi Tanaka, “A Japanese View: Coral Sea to 

Midway,” in Battle of the Coral Sea 1942, p. 79. 

157 Ibid., p. 78.

158 Bates et al., Battle of the Coral Sea, p. 5.

159 Gill, Royal Australian Navy, pp. 40–41.

160 Morison, History of United States Naval Operations 

in World War II, pp. 10–12.

161 Bates et al., Battle of the Coral Sea, pp. 13–14.

162 Cited in Tanaka, “Japanese View,” p. 79. 

163 Ibid., p. 15.

164 Ibid., p. 13.

165 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 57.

166 Bates et al., Battle of the Coral Sea, p. 14.

167 Willoughby et al., eds., Reports of General 

MacArthur, p. 47.

168 Samuel E. Morison, The Two-Ocean War: A Short 

History of the United States Navy in the Second World 

War (Boston: Little, Brown, 1963), p. 142.

169 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 58.

170 Bates et al., Battle of the Coral Sea, p. 13.

171 Military History Section, Headquarters Army Forces 

Far East, Submarine Operations in Second Phase 

Operations, part 1, April–August 1942, Japanese 

Monograph No. 110 (Washington, D.C.: Office 

of the Chief of Military History, U.S. Army Dept., 

1952) [hereafter Japanese Monograph 110], pp. 6–7. 

172 Gill, Royal Australian Navy, p. 40.

173 Bates et al., Battle of the Coral Sea, p. 15.

174 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 57; Japanese Monograph 110, 

p. 10.

175 Bates et al., Battle of the Coral Sea, p. 15.

176 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 58.

177 Henry F. Schorreck, “Battle of Midway: 4–7 June 

1942: The Role of COMINT in the Battle of Midway 

(SRH-230),” The Navy Department Library, p. 4, 

www.history.navy.mil/.

178 Steven E. Maffeo, U.S. Navy Codebreakers, Linguists 

and Intelligence Officers against Japan (Lanham, Md.: 

Rowman & Littlefield, 2016), p. 75.

179 Ibid.

180 Lundstrom, Black Shoe Carrier Admiral, p. 119.

181 Ibid.

182 Ibid.

183 Parker, Priceless Advantage, p. 21.

184 Lundstrom, Black Shoe Carrier Admiral, p. 119.

185 Parker, Priceless Advantage, p. 17.

186 Ibid.

187 Lundstrom, Black Shoe Carrier Admiral, p. 120.

188 Parker, Priceless Advantage, p. 7.

189 Ibid., p. 16.

190 CINCPac Intelligence Bulletins, 16 March–1 June 

1942, United States Navy Records Relating to 

Cryptology, 1918–1950, entry 9020, SRMN 001, 003, 

009, folder SRMN-004, P-20G file, box 1, RG 457, 

Records of the National Security Agency / Central 

Security Service, NARA.

191 The Role of Communications Intelligence in the 

American-Japanese War, vol. 1, August 1941–June 

1942, for 1 September 1942, Studies on Cryptology, 

1917–1977, p. 211, SRH 012, box 1, RG 457, Records 

of the National Security Agency / Central Security 

Service, NARA.

192 Ibid., pp. 211–12.

193 Rear Adm. Edwin T. Layton Papers, Series II, pp. 

26–27, Unpublished Items, SRH 012, 036, 043, 081, 

and 125, Ms. Ac. 86.10, box 15, Naval Historical 

Collection, Naval War College, Newport, R.I. [hereafter Layton Papers].

194 Ibid., pp. 27–28.

195 Ibid., pp. 28–29.

196 Schorreck, “Battle of Midway,” p. 5.

197 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942.

198 Ibid.

199 Lundstrom, Black Shoe Carrier Admiral, p. 120.

200 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942, for 7 April.

201 Layton Papers, p. 214.

202 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942, for 8 April.

203 Ibid., for 9 April. 

204 Brown and Anderson, Invasion 1942?, annex “Battle 

of the Coral Sea,” p. 5.

205 Cited in ibid., p. 122. 

206 Layton Papers, p. 215.

207 “Summary of Japanese Naval Activities on File in the 

White House Map Room, April 14, 1942,” 26 April 

Supplement, United States Navy Records Relating to 

Cryptology, 1918–1950, SRNS 013, folder 001-0352, 

box 1, RG 457, NARA [hereafter “Summary of 

Japanese Naval Activities”].

208 Edwin T. Layton, “And I Was There”: Pearl Harbor 

and Midway—Breaking the Secrets (New York: Quill, 

William Morrow, 1985), p. 382.

209 Gill, Royal Australian Navy, p. 41.

210 Layton Papers, pp. 215–16.

211 Ibid., p. 217.

212 Ibid., p. 219.

213 Layton, “And I Was There,” pp. 382–83.
J

214 Cited in ibid., p. 383.

215 Parker, Priceless Advantage, p. 22.

216 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942, for 22 April.

217 Parker, Priceless Advantage, pp. 23–24.

218 Ibid., p. 7.

219 Schorreck, “Battle of Midway,” pp. 5–6; Layton 

Papers, p. 221.

220 CINCPac Enemy Activities File, April–May 1942, 

for 25 April, Studies on Cryptology, 1917–1977, 

SRH 272, box 93, RG 457, NARA.

221 “Summary of Japanese Naval Activities,” for 26 

April.

222 Role of Communications Intelligence in the 

American-Japanese War, for 26 April, p. 225; Layton 

Papers, p. 225.

223 Layton Papers, p. 224.

224 Ibid., p. 225.

225 Ibid., p. 227.

226 “Summary of Japanese Naval Activities,” for 27 

April.

227 Role of Communications Intelligence in the AmericanJapanese War, for 27 April, pp. 227–28; Layton 

Papers, pp. 227–28.

228 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942, for 27 April. 

229 “Summary of Japanese Naval Activities,” for 28 April.

230 Role of Communications Intelligence in the 

American-Japanese War, for 28 April, p. 231; Layton 

Papers, p. 231.

231 Lundstrom, First South Pacific Campaign, p. 94.

232 Bates et al., Battle of the Coral Sea, p. 24.

233 Ibid., pp. 24–25.

234 Willmott, Barrier and the Javelin, p. 221.

235 Bates et al., Battle of the Coral Sea, p. 25.

236 Ibid., pp. 25–26.

237 Dull, Battle History of the Imperial Japanese Navy, 

p. 122.

238 Bates et al., Battle of the Coral Sea, pp. 26–27, 122.

239 Chris Coulthard-Clark, “RAN and RAAF Involvement in the Battle of the Coral Sea,” in Battle of the 

Coral Sea 1942, p. 66.

240 Bates et al., Battle of the Coral Sea, p. 20.

241 Lundstrom, First South Pacific Campaign, p. 92.

242 Ibid., pp. 92–95.

243 Ibid., p. 95.

244 Bates et al., Battle of the Coral Sea, p. 23.

245 Lundstrom, First South Pacific Campaign, pp. 94–95.

246 Ibid., p. 93.

247 Lundstrom, Black Shoe Carrier Admiral, p. 122.

248 Ibid.

249 Ibid., p. 126.

250 Lundstrom, First South Pacific Campaign, p. 92.

251 Willoughby et al., eds., Reports of General 

MacArthur, pp. 45–46.

252 Lundstrom, First South Pacific Campaign, p. 100.

253 Ibid.

254 Willmott, Barrier and the Javelin, p. 205.

255 Bates et al., Battle of the Coral Sea, pp. 28–29.

256 CINCPac Operation Plan 23-42, 29 April 1942, p. 1, 

CINCPac Jan 1942 to Apr 1942, box 20, RG 38, Records of the Office of the Chief of Naval Operations, 

Records Relating to Naval Activities during World 

War II: Plans, Orders and Related Documents, 

NARA.

257 Ibid., pp. 1–2.

258 Ibid., p. 2.

259 Lundstrom, First South Pacific Campaign, p. 100.

260 Cited in ibid., p. 101.

261 Lundstrom, Black Shoe Carrier Admiral, p. 137.

262 Japanese Monograph 110, p. 10.

263 Bates et al., Battle of the Coral Sea, p. 26.

264 “The Battle of the Coral Sea, May 4–8, 1942,” Action 

Report, Commander Task Force 17, 27 May 1942, p. 

2, RG 38, Records of the Office of the Chief of Naval 

Operations, Records Relating to Naval Activity during World War II, WW II Action and Operational 

Reports, NARA.

265 Layton Papers, p. 233.

266 CINCPac Enemy Activities File, April–May 1942, 

for 30 April.

267 “Summary of Japanese Naval Activities,” for 30 

April.

268 Ibid., for 14 April. 

269 Cited in Parker, Priceless Advantage, p. 24.

270 Ibid.

271 Ibid., p. 25.

272 Cited in ibid.

273 Role of Communications Intelligence in the 

American-Japanese War, pp. 239–40; Layton Papers, 

pp. 239–40.

274 Bates et al., Battle of the Coral Sea, p. 15.

275 Willmott, Barrier and the Javelin, p. 208.

276 Lundstrom, First South Pacific Campaign, pp. 98–99.

277 “Battle of the Coral Sea, May 4–8, 1942,” p. 2.

278 Bates et al., Battle of the Coral Sea, p. 30.

279 “Summary of Japanese Naval Activities,” for 14 

April.

280 Role of Communications Intelligence in the AmericanJapanese War, p. 241.

281 CINCPac Enemy Activities File, April–May 1942.

282 Cited in Willmott, Barrier and the Javelin, p. 207.

283 Bates et al., Battle of the Coral Sea, pp. 12, 32.

284 Ibid., pp. 30–31.

285 “Battle of the Coral Sea, May 4–8, 1942,” p. 3.

286 Layton Papers, pp. 243–44.

287 Cited in Willmott, Barrier and the Javelin, p. 207.

288 Willoughby et al., eds., Reports of General 

MacArthur, p. 47.

289 Willmott, Barrier and the Javelin, p. 208.
290 Morison, History of United States Naval Operations 

in World War II, p. 25. 

291 Bates et al., Battle of the Coral Sea, p. 39.

292 Ibid., p. 38.

293 Dull, Battle History of the Imperial Japanese Navy, 

p. 121.

294 “Battle of the Coral Sea, May 4–8, 1942,” p. 3.

295 Ibid.

296 Willmott, Barrier and the Javelin, p. 220.

297 Parker, Priceless Advantage, p. 27.

298 Willoughby et al., eds., Reports of General 

MacArthur, p. 47.

299 Brown and Anderson, Invasion 1942?, annex “Battle 

of the Coral Sea,” p. 5.

300 Cited in Parker, Priceless Advantage, p. 27. 

301 Parker, Priceless Advantage, p. 28.

302 Morison, Two-Ocean War, p. 143.

303 Chester G. Hearn, Carriers in Combat: The Air War 

at Sea (Mechanicsburg, Pa.: Stackpole Books, 2007), 

p. 76.

304 Willoughby et al., eds., Reports of General 

MacArthur, p. 47. 

305 Parker, Priceless Advantage, p. 28.

306 Lundstrom, First South Pacific Campaign, p. 104; 

“Battle of the Coral Sea, May 4–8, 1942,” p. 4.

307 Lundstrom, First South Pacific Campaign, p. 100.

308 “Battle of the Coral Sea, May 4–8, 1942,” p. 4.

309 Ministry of Defence (Navy), War with Japan, 

p. 138.

310 Dull, Battle History of the Imperial Japanese Navy, 

p. 124.

311 Arno Sist, Setting Sun: A Critical Analysis of Japan’s 

Employment of Naval Airpower in the Battle of the 

Coral Sea (Maxwell Air Force Base, Ala.: Air Command and Staff College, Air Univ., April 1998), 

p. 11.

312 Cited in Dull, Battle History of the Imperial Japanese 

Navy, p. 122.

313 Gill, Royal Australian Navy, p. 45.

314 Ministry of Defence (Navy), War with Japan,

p. 138.

315 Dull, Battle History of the Imperial Japanese Navy, 

p. 124.

316 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 62.

317 Ibid.

318 Gill, Royal Australian Navy, p. 46.

319 Morison, History of United States Naval Operations 

in World War II, pp. 31–32.

320 Ibid., p. 32.

321 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 62.

322 “Battle of the Coral Sea, May 4–8, 1942,” p. 5. 

323 Ibid.

324 Morison, Two-Ocean War, p. 144.

325 “Battle of the Coral Sea: The Events of 7 May 1942,” 

The Pacific War, p. 4, www.pacificwar.org.au/.

326 Ibid. 

327 Gill, Royal Australian Navy, p. 49.

328 Lundstrom, Black Shoe Carrier Admiral, p. 161.

329 Willmott, Barrier and the Javelin, p. 233.

330 Morison, History of United States Naval Operations 

in World War II, p. 33.

331 Bullard, trans., Japanese Army Operations in the 

South Pacific Area, p. 63.

332 Ministry of Defence (Navy), War with Japan, p. 141.

333 Morison, History of United States Naval Operations 

in World War II, p. 40. 

334 Ibid., p. 139.

335 “Battle of the Coral Sea: The Events of 7 May 1942,” 

p. 2. The time of the attack is also reported as 1115.

336 Gill, Royal Australian Navy, p. 47.

337 Morison, Two-Ocean War, p. 144. 

338 “Battle of the Coral Sea: The Events of 7 May 1942,” 

p. 5.

339 Morison, History of United States Naval Operations 

in World War II, p. 56.

340 Ibid., p. 2.

341 Juergen Rohwer and Gerhard Hummelchen, 

Chronology of the War at Sea 1939–1945: The Naval 

History of World War II, 2nd ed. (Annapolis, Md.: 

Naval Institute Press, 1992), p. 138.

342 Bates et al., Battle of the Coral Sea, p. 87.

343 Morison, Two-Ocean War, p. 145.

344 Commander in Chief, Pacific Fleet, “Action Report 

Battle of the Coral Sea, 4–8 May 1942, 17 June 

1942,” p. 5, available as CD 01573, MilSpecManuals

.com.

345 Morison, History of United States Naval Operations 

in World War II, p. 57.

346 Morison, Two-Ocean War, p. 145.

347 Lundstrom, First South Pacific Campaign, p. 112.

348 Ibid., pp. 112–13. 

349 Morison, History of United States Naval Operations 

in World War II, p. 61.

350 Ibid., p. 115.

351 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942. 

352 Cited in Lundstrom, First South Pacific Campaign,

p. 115.

353 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942. 

354 Cited in Lundstrom, First South Pacific Campaign, 

p. 115.

355 JICPOA-CINCPOA Intelligence Bulletins, 16 

March–1 June 1942.

356 Morison, History of United States Naval Operations 

in World War II, p. 62.

357 Ibid., p. 113.

358 Ibid., p. 63.

II The Midway-Aleutians Operation, 25 May–14 

June 1942

The Japanese Midway-Aleutians operation—or, as it is popularly known in 

the United States, the battle of Midway—represented a turning point in 

the Pacific War of 1941–45. The Imperial Japanese Navy (IJN) suffered the 

greatest defeat in its proud history. After June 1942 Japan was forced onto the strategic defensive and was never able to regain the initiative before its unconditional 

surrender in August 1945. In operational terms, the Midway-Aleutians operation 

comprised in fact two major and “eccentric” offensive naval/joint operations conducted in two adjacent theaters of operations. The U.S. forces involved also conducted two major naval/joint operations, but from a central position. Despite the 

passage of time, the Midway-Aleutians operation is still rich in lessons valid for 

today and in the future.

The Strategic Situation, Spring 1942

The principal objective of the Japanese, in what they called the “First Operational 

Stage of War,” was to destroy and capture the most important American, British, 

and Dutch positions in the western Pacific and Southeast Asia. Subsequently, the 

Japanese planned to secure the positions gained in the southern area. They were 

greatly surprised at the speed and easiness of their own early victories in December 1941–April 1942. 

Prior to December 1941, the Japanese had controlled Korea, Manchuria, and 

coastal areas of China’s mainland. In the Central Pacific, the Japanese were in possession of the Mandates, as they were called (that is, the Marianas [less Guam], 

the Marshalls, and the Carolines). In December 1941 they occupied the U.S.-

controlled Wake Island and Guam.1

 By early 1942 the Japanese had conquered 

Malaya, in a brilliant campaign. The British strongpoint of Singapore fell on 15 

February 1942. The Japanese invaded the Philippines in the first week of December 1941. By 2 January 1942 the capital, Manila, had fallen into their hands, and 

the defending American and Filipino forces had been forced to withdraw to the 

Bataan Peninsula on Luzon. The United States was facing complete defeat in the 

Philippines. 
J

In January 1942, the Japanese also moved into Burma. By 7 March British troops 

had evacuated Rangoon, and by May the Allied forces in Burma were in full retreat. 

Siam (Thailand today) became Japan’s ally, signing a military alliance on 21 December 1941. On 17 December 1941 the Japanese invaded the resource-rich Netherlands 

East Indies (NEI); by 9 March 1942 the entire NEI was in Japanese hands. In the 

process the Japanese decimated the American-British-Dutch-Australian Command 

forces that opposed them. By April 1942 the Japanese had gained control of Southeast Asia and the southwest Pacific, a vast expanse rich in natural resources (oil, tin, 

rubber, and bauxite), and had incorporated it into what they called the “Greater East 

Asia Co-prosperity Sphere.” The Japanese defense perimeters now stretched from 

the Kuril Islands southeastward through Wake, the Marianas, the Marshalls, and the 

Gilbert Archipelago, then along the northern coast of New Guinea through Borneo, 

Java, and Sumatra, up to the Malay Peninsula, and then again westward from the 

borders of Indochina to Siam, Burma, and the border of India. In January 1942 the 

Japanese started an advance into the southwest Pacific. They captured Rabaul, on 

New Britain, in the Bismarck Archipelago, and several key positions in the Solomons. In March 1942 they also seized the ports of Lae and Salamaua on the eastern 

coast of New Guinea and thereby threatened Port Moresby, on Papua New Guinea. 

The Allied navies suffered a series of defeats in the initial phase of the Pacific 

War. In the Japanese view, the remainder of the U.S. Pacific Fleet was now trying 

to regroup. The hub of American activity was Hawaii. American carrier raids in 

the Central and southwest Pacific in early 1942 greatly alarmed the Japanese high 

command. The United States was also reinforcing some key islands in the southern 

Pacific. The Japanese were also concerned that the United States might use the 

Aleutians to stage bombing raids against the Kurils.2

The Theater

The Midway-Aleutians operation was conducted over the major part of the Central 

and northern Pacific. In the Central Pacific, the United States controlled the Hawaiian Islands, a chain of small islands and reefs stretching for about 1,200 miles northwestward from there (Midway, Kure, Pearl and Hermes Reef, French Frigate Shoals, 

Lisianski, and Laysan), and Johnston Island, some 750 miles southwest of Oahu.

Aside from the Hawaiian group, the most important remaining American position in the Central Pacific was Midway Atoll. Midway is an almost-enclosed circular reef about six miles in diameter and consisting of Sand Island and Eastern Island. Sand Island is less than two miles long and encompasses an area of 1.4 square 

miles. Eastern Island is little more than a mile long, with an area of 0.52 square 

miles. Eastern Island is nearly flat, rising only twelve feet above the ocean, while 

the dunes on Sand Island rise to about forty feet, protected from wind erosion by 

six-to-eight-foot evergreen shrubs.3

 The islands lie behind a substantial coral reef 

that protects them from rough seas and all but the most severe tsunamis. Midway 
J

has a semitropical climate, due to the effect of the warm Japanese Current, a stream 

of warm water passing north of the island; the average temperature in the summer 

is seventy-five degrees Fahrenheit and in the winter sixty-five degrees.4

The weather was to have a significant effect on the employment of both the 

Japanese and the U.S. forces in the coming operation. However, the Japanese would 

be much more affected, because of the longer distances their forces had to transit before reaching their operating area near Midway. In May and June of each 

year, storm disturbances frequently pass between northern Japan and Midway. 

They are accompanied by frontal systems that are preceded in turn by rain and 

areas of low visibility. Between periods of storm, fog frequently develops about 

three hundred miles northwest of Midway and extending westward and northward. Frontal systems approaching Midway often dissipate rapidly, leaving broken low and intermediate clouds and reduced visibility. In the northern Pacific, 

surface winds circulate counterclockwise around low-pressure areas and clockwise 

around highs. Because front systems move eastward from Japan’s home islands, 

actual weather conditions to the north and west of Midway could be predicted accurately by Japanese meteorologists several days in advance of their forces’ planned 

arrival. In contrast, the American forecasters no longer had weather stations in 

the northwest Pacific. Hence, they were unable to forecast weather accurately for 

the Midway area. In late May and early June 1942, a large, nearly stationary highpressure area formed northeast of Midway. It caused fronts to the northwest of 

Midway to stagnate and those to the west and southwest to break up. It also produced considerable fog northeast of the island.5

In the northern Pacific, the United States controlled Alaska and the Aleutian 

island chain. The Aleutians extend westward about 1,200 miles from the Alaska 

Peninsula to a point some 230 miles from the Kamchatka Peninsula. They encompass some fourteen large and fifty-five smaller islands plus numerous islets, with 

a combined area of about 6,820 square miles. The great majority of the Aleutian 

Islands are of volcanic origin and hence are uniformly rocky and barren, with precipitous mountains and scant vegetation. The westernmost island, Attu, is about 

twenty-two miles long and twelve miles wide. It is very mountainous, with elevations up to three thousand feet, and has several good harbors. The island of Kiska 

is twenty-two miles long and seven miles wide. The largest island is Unimak, sixtyfive by twenty-two miles, with mountains rising up to 9,300 feet. The coasts of most 

of the Aleutian islands are rocky, and their approaches are very dangerous. Strong 

winds and tidal currents make navigation among the islands very hazardous.

The weather is characterized by violent gales, heavy precipitation, long periods of 

fog, and rapid and unpredictable changes of temperature.6

 Annual rainfall averages 

forty to fifty inches, spread over most of the year. For example, Attu can expect five 

to six days of precipitation per week, with rain or fog of varying intensity, and has 
J

on average no more than eight to ten clear days a year.7 The average temperatures 

are fifty degrees in the summer and thirty-three in the winter. Temperatures below 

zero are rare.8

 During the winter months, a low-pressure system, the Aleutian Low, 

prevails. The Aleutians are subject to frequent cyclonic storms and heavy squalls, as 

well as to snow in the winter and fog in the summer. In fact there is almost constant 

fog, caused by the warm Japanese Current mixing, as it passes about five hundred 

miles south of the Aleutians and then turns southward toward the coast of North 

America, with the cold waters of the Bering Sea. The weather, however, is highly 

localized; areas of high visibility can often be found within twenty miles of fog.9

 The 

weather in the Aleutians is affected as well by the cold water of the Kamchatka (or 

Subarctic) Current, which passes from the Bering Strait to a point midway down the 

Kuril chain, then curves northeastward and passes between the Japanese Current 

and the Aleutians. It is unusually strong in the vicinity of the Aleutians.10

In May and June the weather in the Aleutians is in transition from winter to 

summer. In the summer months most storms move directly through the Aleutians, 

causing extremely variable winds and weather. In the winter there is a severe icing, 

frequent gales, and low clouds.11 Winds are generally gusty because of the deflection of air currents by the steep mountainous slopes. The strongest winds are in 

March. Winds and fogs may persist together for many days. Humidity is always 

high. Special hazards to navigation are “williwaws,” winds that blow down from 

mountains with great force. They sometimes reach gale strength within half an 

hour. The mountains are concentrated on the northern sides of the islands, and 

williwaws make it difficult to find a lee along the northern shores.12

Theater Geometry

The distances separating various points within the Japanese- and the U.S.-controlled 

areas in the northern and Central Pacific were measured in hundreds and thousands of miles (see map 5). For example, the distance from San Francisco to Tokyo 

is about 5,150 miles. The distances from Seattle and San Francisco to Dutch Harbor, on Unalaska Island, are about 1,965 and 2,360 miles, respectively. Some 3,755 

miles separate Pearl Harbor and Hiroshima Bay; Dutch Harbor is about 2,290 miles 

from Pearl Harbor; San Francisco is about 2,400 miles and Seattle 2,680 miles from 

Pearl Harbor. The distance from Pearl Harbor to Midway is about 1,320 miles and 

to Wake, 2,680 miles. Johnston Island and Marcus are 715 and 3,050 miles, respectively, from Pearl Harbor, which is in turn about 3,820 miles from Saipan. The 

distance from Pearl Harbor to Wotje Atoll, in the Marshalls, is about 2,280 miles. 

Attu is some 650 miles from Paramushiro, in the Kurils, and about 1,100 miles from 

Alaska’s mainland. Kiska is about 610 miles west of Dutch Harbor and about 180 

miles east of Attu. 

The employment of the Japanese and U.S. forces during the Midway and Aleutians operations was greatly affected by the number, size, and effectiveness of naval 
J

KAMCHATKA

Petropavlovsk

Hakodate

HOKKAIDŌ

Kure

HONSHŪ 

Vladivostok

IWO JIMA

SAIPAN

GUAM

S E A O F

O K H O T S K

KURIL ISLANDS

MARSHALL ISLANDS

WAKE

ISLAND

ENIWETOK

KAUAI

KURE

MIDWAY

A L E U T I A N I S L A N D S

KOMANDORSKIISLANDS

ATTU

KISKA ADAK

Otter

Point

DUTCH

HARBOR UMNAK

Vancouver

Seattle

YAP

CAROLINE ISLANDS

TRUK

PONAPE

WOTJE

KWAJALEIN

JALUIT

HiroshimaNagasaki

TARAWA

SanFrancisco

BONINISLANDS

Sakhalin Paramushiro

MARIANAS

EXTERIOR

POSITION

U.S. base of operationsJapanese base of operationsU.S. line of operationJapanese line of operation

All distances are in miles.

LEGEND

EXTER OI R POSIT OI N

CENTRAL POSITION

EXTERIOR POSITION

EXTER OI

R

POSITION

AMCHITKA

Tokyo Yokosuka

Kagoshima

Ōminato

KODIAK

JOHNSTON ISLAND

HAWAII

OAHU

FRENCH FRIGATE SHOALS

LAYSAN

LISIANSKI

160° 180° 160° 140° 140° 130° 135° 145° 150° 155° 165° 170° 175° 175° 170° 165° 155° 150° 145° 135° 130° 125°

160°E 180° 160°W 140°W 140°E 130°E 135°E 145°E 150°E 155°E 165°E E 170°E 175°E 175°W 170°W 165°W 155°W 150°W 145°W 135°W 130°W 125°W

60°N40°N20°N45°N50°N55°N35°N25°N30°N15°N10°N

 5°N

60°40°20°45°50°55°25°30°15°10°

 5° 0

50

100

150

200

250nm

MAP 1: THE THEATER AND ITS GEOMETRY

Map 5

The theater and its geometry
J

and air bases. Relative positions, the lengths of respective bases of operations, and 

distances to physical objectives largely dictated the selection and the number of 

lines of operation/retreat, and lines of communications for each side. 

The Japanese had large numbers of well-developed naval bases and airfields in 

the home islands. One of the largest and most important was Hiroshima Bay. The 

majority of the Combined Fleet (Rengō Kantai) was based at Hashirajima Anchorage, in the southern end of Hiroshima Bay. About sixteen miles to the northeast 

was Kure, with a great naval arsenal and shipyards; its anchorage was large enough 

to accommodate the entire fleet. It was also well defended by antiaircraft (AA) batteries and antitorpedo nets, and patrolled by small ships. Each ship when at anchor 

was linked by land phone to the naval headquarters in Tokyo, thereby ensuring 

security of communications.13 At Tokuyama, near the west end of the Inland Sea, 

was the largest fuel depot in the IJN. Maizuru, on the western coast of Honshū, 

was a base for the Special Naval Landing Force (SNLF). The Sasebo naval complex 

encompassed anchorages at Imari and Hirodo and the ports of Takeshiki (Tsushima), Kagoshima, Kuji, and Amami-Ōshima and Wakamatsu (the Gotō Islands). 

Another major naval base was at Yokosuka, Tokyo Bay. 

The most important Japanese naval base in northern Hokkaidō was at Ōminato; 

Akkeshi Bay and Mutsu Bay Anchorages were also used by surface ships. In the 

Kurils, the largest and most important naval base was on the second-largest island, 

Paramushiro. A large airfield capable of accommodating heavy bombers had also 

been built on this island.

The Japanese had few good bases, however, in the Central Pacific. With the 

exception of Truk, in the central Carolines, none were capable of major fleet repairs. Marcus Island had a runway and facilities for ships. Wake Island had a seaplane base. In the Marshalls, Kwajalein Atoll served as an advance submarine base 

and had a newly constructed airfield. There were excellent facilities on Roi Island. 

Ebeye Island, Kwajalein, had a seaplane and submarine base; its lagoon was large 

enough to accommodate a large number of ships. Maloelap had an excellent fleet 

anchorage. A new airfield was built on Taroa Island, in Maloelap Atoll, with seaplane facilities and ramps. Wotje had an airfield with two runways, and it could 

provide a limited support for submarine operations. Jaluit had excellent facilities 

available for handling seaplanes. Eniwetok had a good fleet anchorage, seaplane 

facilities, and a submarine base.14

The U.S. Pacific Fleet used several large, and many smaller, naval bases and airfields along the West Coast; the major ones were at San Diego and Mare Island, California, and Bremerton, Washington. Also available was the Canadian naval base at 

Victoria, British Columbia.15 The largest U.S. Pacific naval base was at Pearl Harbor, 

on Oahu. This large (five hundred acre) base had a navy yard with four large dry 

docks. Pearl Harbor served as a base for both surface ships and submarines. The 
J

naval air station on Ford Island had a 5,400-foot runway and facilities for seaplanes. 

Pearl Harbor also had a large number of fuel, ammunition, and supply depots, and 

power plants, as well as a radio station, naval hospital, and housing for personnel.

Midway had a small base for land and seaplanes, primarily used by patrol aircraft. A small submarine base was used as a refueling point for boats en route or 

returning from patrol. The only airfield was on Eastern Island. There were also 

seaplane facilities inside the lagoon. There were limited fuel supplies for surface 

ships. An underwater telegraph cable connected Midway with Honolulu. On each 

of the main islands there was a radar installation. To the east, small anchorages 

existed at Pearl and Hermes Reef and at French Frigate Shoals. Johnston Island had 

a small naval air station; a few Navy patrol planes operated there, and occasionally 

Army aircraft also. Kure Atoll, some fifty-five miles west-northwest of Midway, had 

a seaplane anchorage in a lagoon.16

Alaska and the Aleutians lacked well-developed naval or air bases. The principal 

bases for U.S. naval forces and aircraft were on Kodiak Island and at Dutch Harbor. 

Dutch Harbor served as a base for submarines and seaplanes. It was protected by 

the Army troops stationed at nearby Fort Hears. Kodiak had a naval air station for 

land aircraft and seaplanes, a submarine base, and limited logistical facilities; it was 

protected by troops at Fort Greely. These bases were supported from Seattle, where 

existed dry-dock and repair facilities.17 In addition, numerous small harbors in the 

Aleutians could be used in an emergency.

In Alaska proper, Ladd Airfield, near Fairbanks, had an Army air base with a 

nine-thousand-foot concrete runway. Nome had an Army staging field and small 

infantry garrison. Anchorage had two operational airfields. Cordova, with one runway, served as the Army staging airfield. Yakutat had an excellent nine-thousandfoot runway for land planes. Juneau had an Army staging airfield; about 485 troops 

were assigned to the base. At Ketchikan was a headquarters for the U.S. Coast 

Guard. Annette Island had an Army staging field; it also served as an operating 

base for a squadron of the Royal Canadian Air Force pursuit planes.18

Japanese ships and naval and land-based aircraft operated from a base of operations stretching from the northern tip of the Kurils through the eastern shores of 

the home islands and the Bonins to the Mandates and Guam. The extreme length of 

this base of operations made it vulnerable to attack. Japanese ships and aircraft had 

to operate along long and converging lines of operation to reach operating areas 

south of the Aleutians and in the vicinity of Midway. Those based in the Mandates, 

however, operated from a central position, which offered relatively short and diverging lines of operations. 

The U.S. base of operations extended from San Diego to Seattle and then curved 

toward Alaska and the Aleutians chain. Hence, like their Japanese counterparts, 

U.S. ships and aircraft operated from a very long and highly exposed base of 
J

operations. The Hawaiian group, together with the chain of islands stretching to 

the northwestward (i.e., out to Kure Atoll), plus Johnston Island to the south, constituted in itself a semicircular, some-two-thousand-mile-long base of operations, 

one that occupied a central position. Hence, the U.S. ships and aircraft based there 

operated along short and diverging lines of operation.

Japanese Strategic Leadership

The Imperial General Headquarters (IGHQ), in Tokyo, was responsible for all the 

strategic and operational planning for both services. It consisted of army and navy 

sections (or general staffs). Plans for major operations prepared by the army or the 

navy were usually made without the input of the other service. Joint operations 

were discussed at liaison conferences. For each major operation, unity of effort 

would be ensured by the terms of an Army-Navy Central Agreement. Afterward, 

the Army and Naval General Staffs would issue final orders for the operation.19

The second-highest planning echelon in the IJN was Combined Fleet Headquarters. Plans prepared at the Naval General Staff and Combined Fleet were afterward elaborated on by the numbered naval and air fleets, sea area (local defense) 

fleets, and subordinate major tactical commands.20 Final plans were prepared after 

discussion between the Commander in Chief (CINC), Combined Fleet, and the 

Chief of Naval General Staff. In theory, strategic decision making for the navy was 

the prerogative of the Naval General Staff. In 1941–42, however, the CINC, Adm. 

Isoroku Yamamoto (1884–1943), often played a dominant role in formulating naval strategy. 

The main reasons were Yamamoto’s strong personality and his enormous prestige and influence in the IJN. He had assumed command of the Combined Fleet in 

1939. Yamamoto was ambitious, smart, and politically adroit.21 He had keen foresight and warmhearted human understanding.22 Yamamoto was very concerned 

that the balance of military strength between the United States and Japan would 

shift against Japan within two years; hence, he felt that Japan’s only hope lay in seeking a quick decision that might induce the enemy to come to terms.23 Yamamoto 

was extremely popular, especially among the aviators—he was one of the foremost 

promoters of naval aviation.24 Yet he created many enemies among senior Japanese 

officers. Among other things, Yamamoto had been a strong supporter of the Washington and London naval treaties and was an opponent of Japan’s alliance with 

Nazi Germany.25 Detractors accused Yamamoto of making the Combined Fleet his 

fiefdom. He also dominated the Japanese naval strategy and thereby effectively undermined the checks and balances of the navy’s strategic planning process.26

Yamamoto was capable of making bold and imaginative decisions. At the same 

time, he insisted uncompromisingly on his plans. He also sometimes made hasty 

decisions. On one hand, Yamamoto exerted strong and unequivocal leadership; 

unlike many other senior Japanese flag officers, he was a true leader. Yamamoto 
J

took active roles in conferences following Combined Fleet maneuvers. Yet he did 

not use his staff officers as his brain trust but rather as aides for executing his own 

ideas.27 He provided his subordinates clear-cut guidance; they always knew what 

they had to accomplish.28 In contrast, neither Adm. Osami Nagano, Chief of Naval 

General Staff, nor his deputy, Vice Adm. Seichi Ito, was very active in the planning 

process. They allowed the staff to take the initiative, expressing their own views 

only when a plan was submitted for their approval. In 1942, Naval General Staff 

thinking largely reflected that of the Plans Division of the First (or Operations) 

Section, led by Rear Adm. Shigeru Fukudome.29

The Japanese Strategic Decision

The Combined Fleet started planning for the Second Operational Stage of the war 

on 5 January 1942.30 The Naval General Staff followed suit in the first half of February. The Combined Fleet began at this time to study the option of invading Midway. 

The genesis of that option was the Combined Fleet’s Operation Order No. 1, of 5 

November 1941, in which Midway and the Aleutians had been listed as positions 

to be invaded or destroyed at the earliest opportune moment. In contrast, the Naval 

General Staff strongly favored capturing Fiji, Samoa, and New Caledonia.31

The views of Yamamoto and his chief of staff, Rear Adm. Matome Ugaki, on 

future operations in the Pacific and adjacent ocean areas were very different from 

those of their counterparts in the Naval General Staff. Ugaki enjoyed a reputation 

as one of Japan’s best officers. He had become Yamamoto’s chief of staff in August 

1941.32 Ugaki agreed with Yamamoto that the enemy had to be decisively defeated 

soon, because time was working to the American advantage. Yamamoto was disappointed that U.S. carriers had not been destroyed in the attack on Pearl Harbor; as 

early as 9 December 1941 he had directed Ugaki to reexamine the idea of invading 

Hawaii, and by early January Ugaki was actively working on it.33

The idea was first to capture and occupy, in early June 1942, Midway Atoll and 

the islands of Johnston and Palmyra (not quite a thousand miles south-southeast 

of Johnston) and then deploy land-based aircraft to them. This would create favorable conditions for an invasion of Hawaii. If possible, the U.S. Pacific Fleet would be 

engaged in a decisive battle. Yamamoto was confident of victory in such a battle.34

On 29–30 March, preliminary plans for the Midway operation were drawn up 

at Combined Fleet Headquarters. On 2 April, Cdr. Yasui Watanabe, the operations 

officer on Yamamoto’s staff, was sent to Tokyo to present the plan officially for approval. He quickly realized that there would be difficulties.35 There was an extensive exchange of views between Watanabe and Cdr. Tasukichi Miyo, First Section’s 

air officer, representing the Naval General Staff. Miyo pleaded vigorously against 

the plan and voiced a long list of objections. He argued that the New Caledonia–

Fiji–Samoa operation was more feasible, some preparations having already been 

made. Also, because of the supply situation for aircraft and air materiel in general, 
J

it would be next to impossible to reequip depleted air groups of the First Air Fleet. 

(The problem with aircraft was in fact very serious. All air units were supposed to 

be equipped with reserve aircraft amounting to some 30 percent of their orders of 

battle. Yet a very large number of units had no reserve aircraft at all and were below 

normal operating strength.)36

The Naval General Staff argued that Midway was near the main naval base of 

the U.S. Pacific Fleet and hence could be strongly defended by carriers, submarines, 

and land-based aircraft. As a result of the Pearl Harbor attack in December 1941, 

the enemy would not be taken by surprise. Japanese forces would operate without 

land-based aircraft for scouting or reconnaissance; that would mean a reduction in 

striking power, because carrier-based aircraft would have to supplement the reconnaissance aircraft of battleships and cruisers. The Naval General Staff did not exclude the possibility that the enemy would come out and fight a decisive battle but 

believed it questionable (as it turned out, erroneously) that he would risk his meager strength to defend Midway. The enemy might well chose to conserve his surface 

strength and, if the island were captured, simply neutralize it, taking advantage of 

its remoteness from Japan and proximity to Hawaii.37 Another major problem was 

that even if Midway were captured, it would be very difficult to supply a garrison 

there. Miyo was doubtful that the loss of Midway would significantly and adversely 

affect American morale.38

On 5 April, discussions continued, with Admirals Ito and Fukudome in attendance. Watanabe reiterated Yamamoto’s position that the success or failure of Japan’s entire strategy in the Pacific would depend on whether the U.S. Pacific Fleet 

was destroyed. Yamamoto strongly believed that by launching the proposed operation against Midway it would be possible to draw out the enemy carrier force and 

destroy it in a decisive battle.39

The Naval General Staff accepted the Midway operation but insisted that it include the simultaneous capture of the western part of the Aleutian chain. This new 

objective arose from the Army General Staff ’s belief that enemy heavy bombers, 

if based in the western Aleutians, could be used for attacks against the Kurils and 

Hokkaidō and that the Japanese had to take countermeasures.40 The Army General 

Staff also argued that capturing part of the Aleutian chain would cut communications between Soviet Russia and the United States; the Naval General Staff agreed.41

The Army General Staff, for its part, approved the plan for the Midway operation 

without difficulty, because it would be predominantly naval in character. The army 

had to provide only a small number of troops to reinforce the SNLF.42

The Naval General Staff and the Combined Fleet Staff greatly differed on the 

timing of the Midway-Aleutians operation. The Naval General Staff contended that 

it should be delayed until late June; the Naval General Staff was unwilling to divert 
J

forces assigned to the Port Moresby–Solomons operation—from which the battle 

of the Coral Sea was to result in early May (see chapter 1)—to offensive operations 

in the Central and North Pacific.43 The Combined Fleet, as noted, wanted the landing on Midway to take place in early June; the Naval General Staff argued for about 

three additional weeks for preparations. However, the Combined Fleet insisted that 

the operation had to be launched with a full moon and that delaying for an entire 

month until the next one might seriously reduce its chances of success.44 Yamamoto 

let it be known that he and his staff were ready to resign if his views were not accepted.45 The Naval General Staff reluctantly agreed on 5 April to his timetable for 

the Midway-Aleutians operation.46

Directive No. 86 for the Second Operational Stage of War was issued by IGHQ on 

16 April.47 Port Moresby was to be occupied in early May 1942, Midway and the Aleutians in early June, and Fiji, Samoa, and New Caledonia (the FS operation) in July.48

The Allied “Doolittle Raid” on 18 April 1942 did not change the IGHQ decision. 

However, it had an effect, in that Yamamoto and other proponents of the MidwayAleutians operation used it to reinforce their insistence that the operation not be 

delayed but carried out as scheduled—to prevent a potential second raid on Tokyo.49

Japanese Plans

On 5 May the Naval General Staff issued to Yamamoto Order No. 18, for the capture of Midway and “strategic” (actually major tactical) points in the western Aleutians in cooperation with the army. On the same day, IGHQ announced an ArmyNavy Central Agreement on the Midway and Aleutians operations. Details were 

contained in IGHQ’s Order No. 94, also issued on 5 May.50

The plan envisaged two separate groups of forces, one for Midway (Operation 

MI) and another for the Aleutians (Operation AL). The forces taking part in the 

Midway operation specifically were divided into five large elements: the Main Force 

(First Fleet), under Admiral Yamamoto; the First Mobile Force (Kidō Butai—a term 

of convenience, not a formal name) (First Air Fleet [Dai-ichi Kōkū Kantai]), under 

Vice Adm. Chūichi Nagumo; the Midway Occupation Force (composed of the Second Fleet; the IJN’s principal surface force), under Vice Adm. Nobutake Kondō; the 

Advance Expeditionary Force (Submarines), under Vice Adm. Teruhisa Komatsu; 

and the land-based (Base Air Force) Eleventh Air Fleet, under Vice Adm. Nishizō 

Tsukahara. 

Nagumo and his carrier force had the most critical role with respect to Midway. 

Nagumo, fifty-five years old, was a torpedo specialist, had held numerous seagoing 

commands, and was held in high esteem in the IJN. He had led the successful attack on Pearl Harbor and the raids in the Indian Ocean. He was very businesslike 

but at the same time personally approachable, sympathetic, and warmhearted toward junior officers. He was also willing to delegate responsibility to subordinates. 
J

Reportedly, Nagumo displayed a lack of initiative and often merely approved recommendations of his chief of staff. By the time of the Midway operation he seems 

to have lacked the vigor and fighting spirit he had once possessed.51 Nagumo was 

on friendly terms with Yamamoto, but Yamamoto was unhappy that Nagumo was 

appointed as commander of the First Air Fleet. He believed Adm. Jisaburo Ozawa, 

who was a more air-minded officer, would have been a better choice.52 Admiral Ugaki disliked Nagumo, attributing to him simple stupidity and a tendency to panic.53

The Northern Area (Aleutian) Force was divided into five major force elements: 

Northern Area Force, Main Body; the Second Mobile Force; the Adak-Attu Occupation Force; the Kiska Occupation Force; and the Patrol/Reconnaissance Group 

(see sidebar 1).

In its Order No. 94, IGHQ stated that by capturing Midway the Japanese would 

prevent future attack on their homeland from the Hawaii area. Also, the enemy 

fleet would be destroyed, if it appeared on the scene of action. The navy and the 

army would capture Midway and quickly establish a base for land aircraft and seaplanes. Kiyua (Kure) Atoll would be captured to facilitate the invasion of Midway. 

The Main Force would support the Midway Occupation Force. The First Mobile 

Force would destroy enemy air strength on Midway prior to the landing. All the 

navy’s forces would be under command of the CINC of the Combined Fleet on 

board the flagship of the Main Force, the superdreadnought Yamato. The army’s 

forces would be led by the IKKI (Ichiki) Detachment commander.54 IGHQ Order 

No. 94 further stated that both the Midway and the Aleutians operations would 

start almost simultaneously in the early part or middle of June. Saipan was to be 

the assembly point for the Midway Occupation Force. The navy would be responsible for protection of the army troops at the ports of embarkation; once they were 

embarked, the fleet commander would be in command of the army units. In the 

course of the landing, the most senior navy or army officer would be in charge. After the capture of Midway, the navy would be responsible for its defense. The army 

units would be withdrawn one week after the island was secured.55

The Combined Fleet’s final plan set the date of the landing on Midway (N-Day) 

as 7/6 June (that is, Tokyo time / Honolulu time). The selection of N-Day was based 

primarily on the need for a full moon to facilitate night movements; 7/6 June was 

the last day until almost a month later when the moon would be right for the landing.56 Another factor was the time required to repair, overhaul, and resupply the 

ships of Nagumo’s First Mobile Force and Kondō’s Second Fleet, which had returned to home waters from the Indian Ocean in late April. The entire MidwayAleutians operation would be completed by 20/19 June.57

After “annihilating” the U.S. Pacific Fleet, the Combined Fleet would return to 

Japan for yet another offensive. Between 15 and 20 June the main body, Second 
J

Japanese Task Organization

Midway Operation

Main Force (First Fleet): Adm. Isoroku Yamamoto, CINC, Combined Fleet Flagship Yamato)

BatDiv 1 (Yamato, Mutsu, Nagato)

1 Light Carrier (Hōshō—8 B4Y1 Type 96 bombers) 

1 Destroyer (Yukaze)

Screen

(Rear Adm. Shintaro Hashimoto, Commander, DesRon 3 [flagship light cruiser Sendai])

DesRon 3

DesDiv 11 (Fubuki, Shirayuki, Hatsuyuki, Murakumo)

DesDiv 19 (Isonami, Shikanami, Ayanami, Uranami)

Special Force

2 Seaplane Tenders (Chiyoda, Nishin—carrying two MTBs and six midget submarines)

1st Supply Group

2 Oilers (Naruto, Toei Maru)

First Mobile Force (Kidō Butai / First Air Fleet) 

(Vice Adm. Chūichi Nagumo, Commander, CarDiv 1 [flagship Akagi])

Carrier Division 1

Kaga (18 A6M2 Type 00 Zeros, 18 D3A1 Type 99 Vals, 18 B5N2 Type 97 Kates)

Akagi (19 A6M2 Type 00 Zeros, 18 D3A1 Type 99 Vals, 18 B5N2 Type 97 Kates)

Carrier Division 2

(Rear Adm. Tamon Yamaguchi [flagship Hiryū])

Sōryū (18 A6M2 Type 00 Zeros, 16 D3A1 Type 99 Vals, 18 B5N2 Type 97 Kates)

Hiryū (18 A6M2 Type 00 Zeros, 18 D3A1 Type 99 Vals, 18 B5N2 Type 97 Kates)

Support Group

(Rear Adm. Hiroaki Abe [flagship Tone])

BatDiv 3, 2nd Section (Haruna—3 E8N2 Type 95s; Kirishima—3 E8N2 Type 95s)

CruDiv 8 (Tone—3 E13A1 Type 0s, 2 E8N2 Type 95s; Chikuma—3 E13A1 Type 0s, 2 E8N2 Type 95s) 

Screening Group 

(Rear Adm. Susumu Kimura, Commander, DesRon 10 [flagship light cruiser Nagara])

DesRon 10

DesDiv 4 (Arashi, Nowaki, Hagikaze, Maikaze)

DesDiv 10 (Kazagumo, Yugumo, Makigumo)

DesDiv 17 (Isokaze, Urakaze, Hamakaze, Tanikaze)

Supply Unit

5 Oilers (Kyokuto Maru, Shinkoku Maru, Tōhō Maru, Nippon Maru, Kokuyo Maru)

1 Destroyer (Akigumo) (assigned on 3 June; from DesDiv 10)

Midway Occupation Force (Second Fleet) 

(Vice Adm. Nobutake Kondō, Commander, Second Fleet [flagship heavy cruiser Atago])

Covering Force, Main Body

(Rear Adm. Gunichi Mikawa, Commander, BatDiv 3, 1st Section)

BatDiv 3, 1st Section (Kongō—3 E8N2 Type 95s; Hiei—3 E8N2 Type 95s)

CruDiv 4, 1st Section (Atago, Chōkai)

CruDiv 5 (Haguro, Myōkō)

Screen

(Rear Adm. Shoji Nishimura, Commander, DesRon 4 [flagship light cruiser Yura])

DesRon 4

DesDiv 2 (Yudachi, Murasame, Harusane, Samidare)

DesDiv 9 (Asagumo, Minegumo, Natsugumo)

Carrier Group

1 Light Carrier (Zuihō—6 A6M2 Type 96s, 6 A5M4 Type 96, 12B5N2 Type 97- Kates)

1 Destroyer (Mirazuki)
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Close Support Group

(Rear Adm. Takeo Kurita, Commander, CruDiv 7 [flagship Kumano])

CruDiv 7 (Kumano, Suzuya, Mikuma, Mogami)

DesDiv 8 (Arashio, Asashio)

1 Oiler (Nichiei Maru)

Transport Group

(Rear Adm. Raizō Tanaka, Commander, DesRon 2 [flagship light cruiser Jintsu])

12 Transports (Kiyozumi Maru, Keiyo Maru, Zenyo Maru, Goshu Maru 2, Toa Maru, Kano Maru, Argentina Maru, 

Hokuriku Maru, Brazil Maru, Kirishima Maru, Azuma Maru, Nankai Maru)

3 Patrol Boats (Patrol Boat No. 1 [old DD Shimakaze], Patrol Boat No. 2 [old DD Nadakaze], Patrol Boat No. 34 

[old DD Suzuki]—carrying Kure and Yokosuka 5th SNLFs [for Sand Island] and Army Ichiki Detachment [for Eastern Island]; 2 construction battalions, survey group, and “weather group”—

total 5,000 men)

1 Oiler (Akebono Maru)

Close Screen

(Rear Adm. Raizō Tanaka, Commander, DesRon 2 [flagship light cruiser Jintsu])

DesRon 2

DesDiv 15 (Kuroshio, Oyashio)

DesDiv 16 (Hatsukaze, Yukikaze, Amatsukaze, Tokitsukaze)

DesDiv 18 (Kasumi, Arare, Kagerō, Shiranuhi)

Seaplane Tender Group (Kure Occupation Force)

(Rear Adm. Rūitarō Fujita, Commander, CarDiv 11 [flagship Chitose])

CarDiv 11

1 Light Seaplane Carrier (Chitose—16 F1M2 Type 0 Pete scouting seaplanes, 4 E13A 

reconnaissance seaplanes)

1 Destroyer (Hayashio)

1 Patrol Boat (No. 35, carrying troops)

Minesweeping Group

(Capt. Sadatomo Miyamoto)

4 Minesweepers (Tama Maru No. 3, Tama Maru No. 5, Shonan Maru No. 7, Shonan Maru No. 8)

3 Submarine Chasers (Nos. 16, 17, 18)

2 Cargo Ships (Meiyō Maru, Yamafuku Maru)

1 Supply Ship (Sōya)

Supply Group 

4 Oilers (Genyō Maru, Kenyō Maru, Sata, Tsurami)

1 Repair Ship (Akashi)

Advance (Submarine) Expeditionary Force 

(Vice Adm. Teruhisa Komatsu, Commander, Sixth Fleet [flagship light cruiser Katori, Kwajalein])

Midway Submarine Group

(Rear Adm. Chimaki Kōno, Commander, SubRon 3 [flagship tender Yasakuni Maru, Kwajalein])

SubRon 3

SubDiv 11 (I-174, I-175)

SubDiv 12 (I-171, I-169, I-168)

SubDiv 13 (I-121, I-122, I-123—taking part in K operation; afterward to be deployed on KO line)

SubRon 5

(Rear Adm. Tadashige Daigo [flagship tender Rio de Janeiro Maru, Kwajalein])

SubDiv 19 (I-156, I-157, I-158, I-159)

SubDiv 30 (I-162, I-165, I-166, I-168)

Eleventh Air Fleet

(Vice Adm. Nishizō Tsukahara, Commander, Eleventh Air Fleet)

Midway Expeditionary Force (6th Air Group)

(Capt. Chisato Morita)

6 A6M2 Type 00s (carried on board Akagi)

9 A6M2 Type 00s (carried on board Kaga)

3 A6M2 Type 00s(carried on board Hiryū)

3 A6M2 Type 00s(carried on board Sōryū)
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22nd Air Squadron (Marcus Island)

12 G4M1 Type 01 Rikko-Betty attack aircraft

24th Air Squadron, 14th Air Group (Jaluit Island)

6 K6K4 Type 97 flying boats

24th Air Flotilla (Kwajalein)

(Rear Adm. Minoru Maeda)

4th Air Attack Force

1st Force (Chitose Air Group, Kwajalein—36 topedo bombers)

1st Air Group (36 A6M2 Type 00, 36 torpedo bombers, Aur, Wotje)

14th Air Group 18 flying boats, Jaluit, Wotje)

Special Duty Units

1 Light Seaplane Carrier (Kamoi Maru)

1 Seaplane Tender (Hogashu Maru)

1 Cargo Ship (Paran Maru)

1 Destroyer (Tachikaze)

Aleutians Operation

Northern Area Force, Main Body: Vice Adm. Boshirō Hosogaya, Commander, Fifth Fleet

Northern Area Force, Main Body 

(Vice Adm. Boshirō Hosogaya [flagship Nachi])

1 Heavy Cruiser (Nachi)

2 Destroyers (Ikazuchi, Inazuma)

Supply Group

2 Oilers (Fujisan Maru, Nissan Maru)

3 Cargo Ships

Second Mobile Force 

(Rear Adm. Kakuji Kakuta, Commander, CarDiv 4 [flagship Ryūjō])

CarDiv 4

Ryūjō (16 A6M2 Type 00 Zeros, 20 B5N2 Type 97 Kates)

Junyō (18 A6M2 Type 00 Zeros, 15 D3A1 Type 99 Vals)

CruDiv 4, 2nd Section (heavy cruisers Takao, Maya)

DesDiv 7 (Ushio, Sazanami, Akebono)

1 Oiler (Teiyō Maru)

Guard Force (Aleutians Screen)

(Vice Adm. Shirō Takasu [flagship Hiyūga])

BatDiv 2 (4 battleships—Hiyūga, Ise, Fusō, Yamashiro)

CruDiv (Light) 9 (2 light cruisers—Kitakami, Ōi)

DesDiv 20 (Asagiri, Yugiri, Shirakumo, Amagiri)

DesDiv 24 (Umikaze, Yamakaze, Kawakaze, Suzukaze)

DesDiv 27 (Ariake, Yugure, Shigure, Shiratsuyu)

2nd Supply Group

2 Oilers (San Clemente Maru, Toa Maru)

Adak-Attu Occupation Force

(Rear Adm. Sentarō Omori [flagship light cruiser Abakuma])

DesRon 1

DesDiv 21 (Wakabe, Hatsushimo, Nenohi, Hatshuharu)

1 Transport (Kinugasa Maru—carrying 1,200–man North Sea [Hokkaidō] Army 

Detachment)

1 Minelayer (Magane Maru)

Kiska Occupation Force

(Capt. Takeji Onoji [flagship light cruiser Kiso])

CruDiv 21 (light cruisers Kiso, Tama)

CruDiv 22 (light cruisers Asaka Maru, Ahata Maru)
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Fleet, and First Mobile Fleet would concentrate at Truk and prepare for the invasion of New Caledonia, Fiji, and Samoa, in cooperation with the newly created 17th 

Army. Reportedly, Hawaii was to be invaded in the latter part of 1942.58

The Plan for the Midway Operation. The basic IJN plan for the Midway operation 

was extremely complex. Moreover, it contained several serious flaws. Among other 

things, the Japanese assumed that everything would work as planned. No adequate 

attention was given to the possibility that the enemy might react to the landing on 

Midway earlier than assumed. Yamamoto presumed that the U.S. Pacific Fleet was 

already beaten and that all that was required was to draw out its carriers to complete their destruction. He failed to take into account the enemy’s will to fight.59

The final plan for the Midway operation envisaged accomplishment of two successive objectives. A major tactical objective was the capture of Midway and its subsequent development as an advance base from which to put under surveillance 

enemy forces operating out of Hawaii. The second and much more important objective was to draw out the U.S. Pacific Fleet’s remaining strength to engage and 

destroy it in a decisive battle. This objective was the operational objective, in terms 

of its scale. Yamamoto was convinced that a landing on Midway would almost certainly provoke an enemy reaction, because the island was important for defense of 

Hawaii.60 The landing would not require that the Japanese first obtain local sea control (as they needed but failed to do in their unsuccessful Port Moresby–Solomons 

operation). They would probably obtain at least temporary sea control in the North 

and Central Pacific if they succeeded in destroying the U.S. Pacific Fleet’s carrier 

force—that is, the enemy operational center of gravity. 

Operational Idea. The operational idea for the Midway operation followed a 

standard Japanese pattern. The sequencing of the objectives was meticulous but 

Screen

DesDiv 6 (Hibiki, Akatsuki, Hokaze)

Minesweeper Division 13 

3 Auxiliary Minesweepers (Hakuhō Maru, Kaihō Maru, Shinkotsu Maru)

Transports

2 Transports (Hakusan Maru—carrying the 550-man Maizuru SNLF; Kumagawa Maru—carrying 700 labor 

troops and construction equipment)

Seaplane Tender Group

1 Seaplane Tender (Kimikawa Maru—8 E13A1 Type 00s)

1 Destroyer (Shiokaze)

Patrol and Reconnaissance Group (SubRon 1)

(Rear Adm. Shigeaki Yamazaki [flagship I-19])

SubDiv 2 (I-15, I-17, I-19)

SubDiv 4 (I-25, I-26)

Sources: Bates, Battle of Midway, pp. 241–43; Fuchida and Okumiya, Midway, pp. 80–84; Morison, History of United States 

Naval Operations in World War II, vol. 4, pp. 87–93, 172–74; Parshall and Tully, Shattered Sword, pp. 450–61.
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extremely rigid. Little if any flexibility was given to subordinate commanders to 

improvise in case the original schedule was for some reason derailed. 

One of the key elements for Japanese success in the Midway operation was timely information on the presence of enemy carriers in the prospective operating area. 

Hence, Yamamoto ordered a second “K operation,” air reconnaissance of Pearl Harbor, for N–7 (31/30 May—the first K operation having been flown in early March, 

as described below; see map 6). If the conditions were unfavorable that day the 

operation would be postponed, but if it could not be carried out prior to N–4 (3/2 

June), the entire operation would be canceled.61 Two Kawanishi Type 2 flying boats 

of the 24th Air Flotilla would be used in the K operation. They would take off from 

Wotje and make an intermediate stop at French Frigate Shoals, where they would 

be refueled by three boats of Submarine Division (SubDiv) 13 (part of Submarine 

Squadron [SubRon] 3) in the evening of 30 May (Honolulu time). They would 

fly to Pearl Harbor, reconnoiter, looking for carriers and battleships, and return 

directly to Wotje.62 One submarine would serve as a beacon west of French Frigate 

Shoals; one boat would be stationed south of Hawaii to rescue pilots if necessary; 

and another would report weather conditions.63 On N–5 (2/1 June), it was planned 

to establish three submarine cordons, or screens, off the approaches to Hawaii and 

Midway. Specifically, two cordons of one squadron each would be deployed northwest and west of Hawaii (and halfway between Hawaii and Midway); another cordon, of one squadron, would be deployed farther north, toward the Aleutians. All 

of them would reach their assigned positions by 2/1 June (N–5).64

At 0130 on N–2 (5/4 June) and until N-Day the First Mobile Force would launch 

pre-invasion air strikes on Midway from about 250 miles northwest of the island.65

The aim would be to destroy enemy air strength, installations, and any surface forces 

nearby. On N–Day (6/5 June) the Seaplane Tender Group would occupy Kure Atoll 

to use it as a seaplane base for direct support of the Midway landing. In the meantime, the Transport Group, carrying some five thousand troops, would move toward its objective with its escorts. At dawn on N-Day (7/6 June) the Transport 

Group would put the landing force ashore simultaneously on Eastern Island and 

Sand Island, supported by the Close Support Group of heavy cruisers; the main 

body, Second Fleet, would take a position south and southwest of Midway to screen 

the flank of the landing. It was expected that any major enemy fleet reaction would 

happen after the landing. Hence, on N-Day the Japanese forces would move into 

positions of readiness for a decisive battle. The forces assigned to fight that battle 

were the First Mobile Force, the main body of the Second Fleet, the Main Force’s 

Guard Force (Aleutians Screen), and elements of the submarine force.66

Combined Fleet planned to use several tactical methods in a decisive battle during the Midway operation. Should the enemy force move west of 160° east longitude, it would be attacked first by the cruisers and submarines, with surface combat 
J

KAMCHATKA

Petropavlovsk

Hakodate

HOKKAIDŌ

Ōminato

Tokyo

Yokosuka Kure

HONSHŪ

Vladivostok

IWO JIMA

SAIPAN

GUAM

S E A O F

O K H O T S K

KURIL ISLANDS

MARSHALL ISLANDS

WAKE

ISLAND

ENIWETOK

JOHNSTON

ISLAND

HAWAII

OAHU

KURE MIDWAY

A L E U T I A N I S L A N D S

KOMANDORSKIISLANDS

ATTU

KISKA

ADAK

DUTCH

HARBOR KODIAK

Vancouver

Seattle

Portland

YAP

CAROLINE ISLANDS

TRUK

PONAPE

WOTJE

KWAJALEIN

TAROA

JALUIT

Prince Rupert

HiroshimaNagasaki

TARAWA

SanFrancisco

BONINISLANDS Kagoshima

Sakhalin Paramushiro

MARCUS

ISLAND

MARIANAS

OTSU LINE

8 SS

N–1 DAY

(6/5 JUNE)

CANCELED

N–1

(6/5 JUNE) N-DAY

(7/6 JUNE)

MAP 2: JAPANESE OPERATIONAL IDEA (SCHEME)

SEAPLANE

TENDER

GROUP

TRANSPORT

GROUP

5,000 Troops

ESTABLISH

SEAPLANE

BASE

N–3

(4/3 JUNE)

SUBRON 1

6 SS

N+5 DAY

(12/11 JUNE)

N–1

(6/5 JUNE)

N-DAY

AIR RAID

(7/6 JUNE)

N–5

(2/1 JUNE)

SUBDIV 13

3 SS N–5

(2/1 JUNE)

N–7

(31/30 MAY)

OPERATION K

CANCELED

30/29 MAY

24th AIR FLOTILLA

LEGEND

= LANDING ON MIDWAY= OBJECTIVE

N-DAY

SECOND

MOBILE

FORCE

ADAK-ATTU

OCCUPATION

FORCE

KISKA

OCCUPATION

FORCE

FIRST MOBILE FORCE

PRE INVASION STRIKES

N–2 to N-DAY

(5/4–7/6 JUNE)

FRENCH FRIGATE

SHOALS

SUBRON 5

N–5

(2/1 JUNE)

SUBRON 3

KO LINE

3–4 SS

160° 180° 160° 140° 140° 130° 135° 145° 150° 155° 165° 170° 175° 175° 170° 165° 155° 150° 145° 135° 130° 125°

160°E 180° 160°W 140°W 140°E 130°E 135°E 145°E 150°E 155°E 165°E 170°E 175°E 175°W 170°W 165°W 155°W 150°W 145°W 135°W 130°W 125°W

60°N55°N50°N45°N40°N35°N30°N25°N20°N15°N10°N

 5°N

60°55°50°45°40°30°25°20°15°10°

 5° 0

50

100

150

200

250nm

Map 6

Japanese operational idea 

(scheme)
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forces coming up and giving support as the situation warranted. If the enemy advanced north of 40° north latitude, the attack would be conducted by the Second 

Mobile Force and SubRon 1, supported by the Guard Force. If south of that line, 

the enemy fleet would be attacked by the First Mobile Force and SubRons 3 and 5, 

supported by the main body of the Second Fleet and Main Force of the First Fleet. 

If the enemy advanced in full strength, the Midway and Aleutians forces would 

unite and engage it. In that case, the Guard Force would rejoin the main body, and 

the First and Second Mobile Forces would be combined and put under Nagumo’s 

command.67 Should the enemy advance westward in full force and the entire fleet 

be required, SubRon 1, assigned to the Northern Area Force, would be put under 

the direct command of the submarine force commander.68

The Japanese believed that the attack on Midway would surprise the Americans 

and so felt free to divide their forces as they pleased. In the event, all major forces 

were deployed beyond mutually supporting distances. Yamamoto’s Main Force 

would be deployed about six hundred miles northwest of Midway. The First Mobile 

Fleet would operate some three hundred miles east of the Main Force. The main 

body of the Second Fleet would be deployed south and southwest of Midway and 

some six hundred miles to the north of the First Mobile Force. The Guard Force 

would be located about five hundred miles northward of the Main Force. The Second Mobile Force would operate some three hundred miles east of the Guard Force.69

Missions. The First Mobile Force mission was to destroy the enemy fleet by decisive 

action and provide support to the Midway Occupation Force. The rigid scheduling 

of N-Day and positioning for delivering pre-invasion strikes by the First Mobile 

Force greatly restricted the freedom of action of Nagumo’s force.70 The Main Force 

would provide support to the First Mobile Force. The Guard Force would initially 

support the Aleutians operation. The Midway Occupation Force was divided into 

nine smaller force elements. The Transport Group would land five thousand men 

of the Kure and Yokosuka SNLFs and the army’s Ichiki Detachment, under the 

cover of the Close Support Group.71 The main body would provide distant cover 

to the Transport Group and Close Support Group. The Seaplane Tender Group 

would establish a seaplane base on Kure Atoll. The Minesweeping Group would 

clear mines in the approaches to Midway’s landing beaches.72

The Advance Expeditionary Force (Submarines) was tasked with conducting 

reconnaissance and destroying enemy surface forces. In the area between Hawaii 

and Midway would be deployed two submarine squadrons and one division.73

SubRon 3, with eight boats, would patrol along Cordon A (KO line) some 300 nautical miles west of Oahu, Hawaii. SubRon 5, with eight boats, would patrol along 

Cordon B (OTSU line) some 450 nautical miles northwest of Oahu. These submarines were tasked to reconnoiter the approaches to Pearl Harbor between late May 

and 3 June. SubDiv 13, with three boats, was assigned as logistical support for the 
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planned flying-boat mission from French Frigate Shoals (the K operation). Each of 

its boats carried forty tons of aviation gasoline and twelve tons of lubricating oil, 

and their torpedoes had been removed.74 After the completion of the K operation, 

SubDiv 13’s boats would patrol along Cordon C (the HEI line).75 The Japanese planners envisaged using Midway as an advanced base for their submarines.76

All land-based naval aircraft (of the Base Air Force) in the Central Pacific were 

assigned to the Eleventh Air Fleet, composed of two air flotillas, the 24th and the 

26th. The 24th Air Flotilla was deployed in the Marshalls and on Wake Island. 

With augmentation from the 26th Air Flotilla, it was operationally designated the 

“4th Air Attack Force.” Its commander, Rear Adm. Minoru Maeda, was in charge 

of all naval land-based aircraft in support of the Midway operation. The Chitose 

Air Group became the 1st Air Attack Force; the 1st Air Group became the 2nd Air 

Attack Force, and the 14th Air Group, the 3rd Air Attack Force. The 26th Air Flotilla (less its detachment to the 24th) was in the home islands and on Marcus Island. 

Fighter units from the 25th Air Flotilla were temporarily assigned to the carriers in 

the Midway-Aleutians operation.77

The 1st Air Attack Force would conduct patrols of the northern section of the 

Marshalls and the Wake Island area. The 2nd Air Attack Force would patrol the 

central part of the Marshalls. The 3rd Air Attack Force would patrol southern sections of the Marshalls and Gilbert Islands and reconnoiter Howland, Baker, Nauru, 

Ocean, and Ellice Islands. Tender Kamoi Maru would cooperate with the 14th Air 

Group at Imieji and Wotje; one cargo ship would transport supplies and base personnel of the 14th Air Group. One destroyer would perform screen duties for the 

3rd Air Attack Force and transport aviation supplies and material; one cargo ship 

would transport personnel and supplies as assigned. Detachments of the 1st and 

3rd Air Attack Forces would be deployed to Midway when directed and report to 

the commander of the 6th Air Attack Force there. The 4th Air Attack Force was 

tasked to conduct patrols in the Marshalls, as well as to intercept and destroy enemy fleet units and to attack the enemy’s installations on Oahu.78

The Plan for the Aleutians Operation. The Japanese attack on the Aleutians was 

planned as a major secondary and offensive naval/joint operation. Despite some 

claims to the contrary, it was not primarily designed as a feint or meant to draw 

enemy forces away from the sector of main effort—that is, Midway-Hawaii. The ultimate objective of the Aleutians operation was operational in its scale. It comprised 

a number of intermediate major and minor tactical objectives (air raids on Dutch 

Harbor, Adak, and Kiska; the capture and destruction of installations on Adak; the 

capture of Attu and Kiska; and so on). The Japanese originally planned to withdraw 

their forces from the western Aleutians in mid-September before the onset of winter.79 The western Aleutians would be of little use as air bases during the greater 

part of the year because of severe weather conditions. Nevertheless, the Combined 
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Fleet’s planners did calculate that their temporary capture would, in addition to its 

primary aim of destroying enemy installations there, protect the northern flank of 

the Japanese thrust toward Midway and act as a diversion that might throw the enemy off balance. The Japanese planners also believed that air patrols eastward from 

the home islands would provide warning of enemy movements from the north.80

The Army-Navy Central Agreement of 5 May stated that the objective of the 

Aleutians operation was to capture or destroy points of “strategic” value in the 

western Aleutians to check the enemy air and ship maneuvers in this area. The 

army and navy, in close cooperation, would invade Attu and Kiska and destroy 

installations and equipment on Adak. The navy would provide “strong” support 

for the invasion forces and at the same time send a carrier unit to raid Dutch Harbor, for the main purpose of reducing enemy air strength prior to the landings. 

The overall commander would be the CINC of the Combined Fleet. The commander of the army troops (a single battalion and one engineer company) would 

be commander of the North Sea Detachment. The invasion force would assemble 

at Akkeshi Bay, on Hokkaidō, on or about 23 May. The navy would be responsible 

for the transport and escort of army units from the point of embarkation to the 

assembly point.81

Vice Adm. Boshirō Hosogaya, the CINC of the Fifth Fleet, would take over operational control of the army units immediately after the time of their assembly. 

Should both the army and navy units be engaged in the same area ashore or in 

landing operations, the senior commander of either service would take charge. Operational orders were issued on 12 May, by which forces assigned to the Aleutians 

operation were directed to assemble at Ōminato.82

On 20 May, the Northern Naval Force issued Order No. 24, specifying the objectives of the Aleutians operation as follows: “(1) destroy the enemy forces and 

military installations at Dutch Harbor and Adak; (2) attack and occupy Kiska and 

Attu so as to restrict and prevent enemy offensive sea and air operations in the 

North Pacific; and (3) to maintain our (Japan’s) offensive policy, detailed plans, and 

alternative plans had to be formulated.” The same order provided details of five 

pre-scripted alternative courses of action for the Japanese forces, depending on the 

conditions at the time of the operation.83 IGHQ had considered occupying Dutch 

Harbor but abandoned the idea because of insufficient shipping.84 Yamamoto made 

in the Aleutians operation the same error he did for Midway, widely dispersing the 

main force elements. For example, the Second Mobile Force would be three hundred miles east of the Guard Force.85

Order No. 24 envisaged a three-“distribution” (phase) operation. In the first 

phase, naval forces would provide cover and support the initial landings, until 

control was turned over to the land forces. Specifically, the Adak-Attu Occupation 

Force would destroy installations on Adak and invade Attu.86 The Kiska Occupation 
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Force would invade that island. The six submarines of SubRon 1 would be responsible for “patrolling, locating, and attacking vital operational areas.” The Toko Air 

Group Detachment (six flying boats and four transports) would locate and attack 

enemy ships.87 The Aleutians operation had the same N-Day as the Midway operation. The operational idea for the Aleutians operation envisaged that on N–3 (4/3 

June) the Second Mobile Force would carry out a raid against Dutch Harbor aimed 

at making that base inoperable. On N–1 Day (6/5 June) the Second Mobile Force 

would conduct air raids on Adak and Kiska.88 On N–1 Day (6/5 June), the AdakAttu Occupation Force would (as originally planned) land on Adak, destroy installations there, and then withdraw.89 On N-Day (7/6 June), the SNLF would land 

and occupy Kiska. On N+5 (12/11 June) the army North Sea Detachment would 

advance to Attu and occupy the island. 

The Aleutians landings would be supported by the Second Mobile Force, the 

main body of the Fifth Fleet, the Guard Force, and elements of the submarine 

force.90 The Seaplane Tender Group would be deployed to the Kiska area to reconnoiter the Bering Sea just north of the Aleutians subsequent to the landings. Submarines would scout “strategic areas” of the Aleutians and monitor the entrance 

of the port of Seattle;91 the six boats of SubRon 1 would be deployed there. IGHQ 

made a decision to limit landings in the western Aleutians to Attu and Kiska. Yamamoto accordingly revised his plans and rescinded the landing on Adak.92

In the second phase of the operation, naval forces would provide support during 

the consolidation phase of the landing in the western Aleutians until such time as 

there was little possibility of the enemy’s counterattack.93The Adak-Attu Occupation Force would be dissolved and its surface ships reassigned to the main body, 

Fifth Fleet. Additional forces would be assigned from the forces that had taken part 

in the Midway operation.

In the third phase, the Japanese naval forces would be reorganized for the longterm defense of the area. The Fifth Fleet would be responsible for defense of the 

occupied areas of the western Aleutians, as well as Midway and the approaches to 

the home islands. The end of the third phase was set for 20 June 1942.94 In addition 

to one heavy cruiser (Nachi), three light cruisers, and seven destroyers, the Fifth 

Fleet would also have four Kongō-class battleships, eight heavy cruisers, and three 

light carriers (Ryūjō, Junyō, and Zuihō), plus the large carrier Shōkaku (its Coral Sea 

damage repaired) and seven additional boats of SubRon 2.95

Logistical Support. Underway logistical support for the Midway and the Aleutians 

operations would be provided by fleet oilers and supply ships. Each combatant formation would be followed by a group of oilers and supply ships, under the direct 

command of the supported unit’s or group’s commander. The Japanese commanders tried to refuel ships at every opportunity. In no case was the fuel on hand to be 

allowed to drop below 60 percent of total capacity. When within striking distance 
J

of the enemy, smaller ships were refueled, as was the practice in the U.S. Navy, from 

battleships. For the Midway operation, all ships were loaded with three months’ 

supply of stores, food, and medical supplies, in addition to the normal load of arms 

and ammunition.96 The oilers would be able to provide support for up to one week.97

Deployment Plans. Deployment of the Combined Fleet forces taking part in the 

Midway-Aleutians operation was predicated on the selection of the N-Day. To 

meet an N-Day of 7/6 June, all the forces had to sortie between 26 and 29 May. 

The Northern Area Force would sail from Ōminato, and the Midway Occupation 

Force (except for the main body) from Saipan and Guam in the Marianas. Kondō’s 

main body, Nagumo’s First Mobile Force, and the Main Force under Yamamoto 

would sail out from Hashirajima Anchorage, in the western part of the Inland Sea, 

and head directly to the operating area. The Main Force would split en route into 

two parts: the Guard Force would veer off to the northeast to screen the Aleutians 

operation while its major part under Yamamoto would continue toward Midway.98

Reaction to the Plan. The reactions of subordinate commanders to Yamamoto’s plan 

ranged from enthusiastic support to skepticism. For example, Admiral Hosogaya 

welcomed the operation, because he was eager finally to see some combat. Rear 

Adm. Tamon Yamaguchi, commander of Carrier Division (CarDiv) 2, was enthusiastic and one of the staunchest supporters of the plan. In contrast, Kondō and his 

staff had great misgivings. Kondō preferred to attack New Caledonia to cut off lines 

of supplies between the United States and Australia.99 Admiral Tsukahara too was 

disappointed with Yamamoto’s decision. He had expected the next major operation 

to be in the Indian Ocean and already moved his headquarters to Bangkok. (As it 

turned out, his land-based aircraft would play no role in the Midway operation.) 

The only forthright opposition came from the CINC of the Fourth Fleet, Vice Adm. 

Shigeyoshi Inoue. He felt that considering Japan’s limited resources, the capture of 

Midway would dangerously overextend the area to be defended. He bluntly told 

Combined Fleet that the Fourth Fleet would be unable to supply Midway after it 

was captured.100

Future Plans. Yamamoto intended that the majority of forces taking part in the 

Midway operation would thereafter assemble at Truk, on or about 20 June, to prepare for the FS operation, in early July. The Main Force would return to its home 

bases in Japan or proceed to Truk to support the FS operation. The submarine force 

would continue its Hawaiian operations for the time being from its new advance 

base at Midway. The majority of the Northern Area Force would return after the 

Aleutians operation to Ōminato. The Guard Force would return either to Ōminato 

or to Tokyo Bay. It would then be employed to protect transports within the Midway and Aleutians areas and would prepare to counter enemy actions east of the 
J

home islands during the next phase of the war. The submarine force would continue the Aleutians operation.101

Information Available to the Japanese Commanders

In planning the Midway-Aleutians operation, Combined Fleet relied on information obtained from radio direction finding (RDF), radio intercepts, scouting by 

land-based aircraft and seaplanes, and exploitation of open sources. The most important source of radio intercepts for the Japanese was the Owada Mura Communications Unit, at Musashino, which continuously monitored all enemy radio 

transmissions.102 The Japanese were unable to break the Allied codes used in radio 

communications and therefore lacked knowledge of American intentions. 

In late May 1942, the Japanese estimated that in the Hawaiian area there were 

about sixty flying boats, a hundred Army bombers, and two hundred fighters.103 Surface strength was estimated at two or three carriers, two or three “special” (escort) 

carriers, four or five heavy cruisers, three or four light cruisers, some thirty destroyers, and twenty-five submarines.104 These estimates were correct except that no 

battleships were actually present, and only eight cruisers and fourteen destroyers 

were available at the time of battle.105 The Japanese estimated (erroneously) that 

about six “special” carriers had been completed and that about half of them were 

in the Pacific.106

The Japanese assumed that the carriers Hornet and Enterprise were at Pearl Harbor. The carrier Ranger was believed definitely to be operating in the Atlantic. The 

carrier Lexington was believed to have been sunk by a Japanese submarine near 

Hawaii in January 1942, but there were reports that it had returned to the U.S. 

west coast and was undergoing repairs.107 (It was actually Saratoga that had been 

attacked; but it had survived and was being repaired in Bremerton.) The Japanese 

were unable to obtain any information on Wasp.

108 On 18 May, a search plane of 

the Fourth Fleet (South Seas Force) detected an enemy task force of two carriers 

to the east of the Solomons, a sighting that suggested that Hornet and Enterprise 

had sortied from Pearl Harbor to operate in the southwest Pacific. This report was 

confirmed subsequently by radio intelligence.109

Japanese naval intelligence assessed that Midway was defended by about 750 

Marines and Coast Guardsmen and by AA artillery.110 In contrast, the army believed 

that there were some two thousand Marines and fifty to sixty planes on Midway.111

The Japanese estimated that in the Midway area the enemy had twenty-four patrol 

aircraft, twelve Army bombers, and twenty fighters and that these numbers could 

be doubled in an emergency. Several patrol boats were assessed to be stationed at 

Midway and a number of submarines operating to the west of the island. The correct figures for 3 June were one and a half flying-boat squadrons with thirty PBY 

Catalina flying boats, one Marine fighter squadron, twenty-one Army bombers, 
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one Marine dive-bombing squadron (thirty-four planes), twenty-one Army bombers (four B-26s and seventeen B-17s), and six Navy torpedo bombers.112 The air 

strength on Midway could in fact be rapidly doubled as soon as a Japanese intention to attack was known.113

The Japanese believed that the enemy flying boats were conducting regular 

day and night patrols over a semicircular area west of Midway out to six hundred 

miles.114 They also assessed that the patrols in the northwestern and northern sectors from Midway were not “strict” (thorough). However, the Japanese erred in this, 

because in fact American patrol aircraft flew daily searches out to seven hundred 

miles and covered also the northern sectors from Midway. The Japanese believed 

that after 29 May the enemy had conducted aerial patrols at Midway, Hawaii, the 

Aleutians, and Palmyra, even in bad weather.115

The Japanese had neither precise nor reliable information on the Aleutians.116

Their information on the military topography of the islands was out of date beyond 

the most rudimentary data on terrain. In mid-May the Japanese planned a secret 

seaplane reconnaissance of the area west of Adak. Seaplanes flew from a tender 

(Kimikawa Maru), which was escorted by one light cruiser. The mission was unsuccessful, because of inclement weather; in addition, the only telephotographic reconnaissance of Kiska attempted was abandoned because of bad weather. The Japanese 

also had only a meager amount of data about the enemy strength in Dutch Harbor.117

Prior to 26 May, a Japanese submarine conducted reconnaissance of the Attu, 

Adak, and Kiska areas. It reported that there were no enemy ships present or important installations. On 27 May a report from another Japanese submarine, reconnoitering the Kodiak area, indicated one enemy heavy cruiser and one destroyer 

entering the harbor. The same submarine also reported the presence of three patrol 

boats and one destroyer at Women’s Bay, some six miles southwest of Kodiak, and 

two patrol boats at Kodiak. On 29 May, a Japanese submarine reported two destroyers, one naval transport or minelayer, and some patrol boats at the entrance 

of Dutch Harbor. On the 30th, a Japanese submarine on its way to its assigned 

patrol area off Seattle sighted naval vessels seven hundred miles west-northwest of 

that city, heading northwest. The Owada Mura Communications Unit detected the 

presence of three to four enemy ships at Kodiak, one believed to be a light cruiser, 

and three to four warships at Dutch Harbor.118

The Japanese believed the enemy had deployed several destroyers, two gunboats, and one tender for small flying boats in the Aleutians. They assumed that 

there were extensive military facilities at Dutch Harbor and that military installations also existed on Adak, Kiska, and Attu.119 The Japanese believed that Dutch 

Harbor was garrisoned by about 4,750 Army troops and 640 sailors.120 They also 

estimated that ground defenses at Dutch Harbor had been recently reinforced 

and that twenty planes had been deployed at Dutch Harbor and Kodiak.121 They 
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estimated that on Attu the enemy had troops (in unknown numbers), a wireless 

station, and a weather reporting station.122 The anchorage on Attu was known to 

be capable of accommodating seaplanes. The Japanese believed that on Adak the 

enemy had only a wireless station. The Bay of Alliance on Adak Island, they noted, 

could accommodate a large number of ships.123 They falsely believed that on Kiska 

the enemy had two to three hundred Marines (in fact, there were only ten unarmed 

men) plus one wireless station and an observation station.124

Japanese Preparations

By the end of April, the majority of the forces—with the exception of CarDiv 5, 

Zuikaku and Shōkaku, detached for the operation against Port Moresby—that were 

meant to take part in the Midway operation had been concentrated. The main assembly point was Hashirajima Bay.125

The Combined Fleet did not have sufficient time to make thorough preparations 

for the Midway-Aleutians operation. The First Air Fleet and Second Fleet did not 

return to home waters until 22–23 April 1942. Also, many ships had to be sent on 

a fruitless search for the enemy carrier force that raided Tokyo and other cities on 

18 April. All the ships required much time for maintenance and repairs, and their 

crews needed rest after being at sea for almost five months. By late April, all the 

ships had gone into repair and maintenance periods. The carrier pilots underwent 

training at Kagoshima (Akagi), Kanoya (Kaga), Tomitaka (Hiryū), and Kasanohara 

(Sōryū), while the bomber leaders trained at Iwakuni. 

No major accidents occurred during training. Nagumo stated that inexperienced pilots had barely reached the point where they could make daytime landings 

on their carriers. Even some of the more experienced pilots had lost some of their 

skills. There was no opportunity to exercise together two or more carriers. The 

results of a mock torpedo firing on 18 May were disappointing. There was also insufficient time for training the pilots of dive-bombers. Night-flying skills had been 

greatly reduced by replacement and transfer of personnel. In general, the combat 

effectiveness of each ship was greatly lowered because the need for repairs and 

maintenance left inadequate time for training.126

In addition, CarDiv 5 would be unavailable for the Midway-Aleutians operation. This reduced the overall strength of the First Mobile Force to 250 aircraft 

(including twenty-one Zero fighters to be ferried to Midway). Shōkaku arrived in 

Japan heavily damaged on 17 May for repairs that would need at least three months. 

Zuikaku arrived home on 21 May undamaged but with less than 40 percent of its 

aviators; the plan was now to redeploy Zuikaku to Truk to take part in the FS operation. Nevertheless, Yamamoto insisted that the Midway-Aleutians operation proceed as scheduled.127

The time for preparation of the Northern Area Force was also inadequate. 

Both light carriers of the Second Mobile Force and their accompanying destroyers 
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required thorough maintenance. In addition, three destroyers assigned to the 

Fifth Fleet returned to Ōminato from the southwest Pacific just one day before the 

scheduled departure for the new operation.128 The shore installations at Akkeshi 

Bay were also unable to handle such a large force, and there were difficulties in 

obtaining adequate supply of oil. Hence, the assembly point was shifted to Mutsu. 

On 9 May, the army’s North Sea Detachment (1,200 men) was formed. It departed 

thirteen days later on board a transport, arriving at Ōminato with one destroyer on 

23 May.129 This detachment and the 3rd SNLF, from Maizuru, were put under command of Admiral Hosogaya.

On 1 May, the Combined Fleet conducted four days of war games on board 

Yamato to test the feasibility of the plan. The war game, directed by Admiral Ugaki, 

went according to the script. During the game Nagumo’s force was attacked by 

enemy land-based aircraft while his planes were bombarding Midway. It was ruled 

by umpires that Akagi and Kaga had been hit by nine bombs and sunk; Ugaki arbitrarily reduced the number of hits to only three, leaving Kaga sunk but Akagi only 

slightly damaged. Even that damage was subsequently made moot when Akagi and 

Kaga reappeared as participants in the follow-on phase of the game, covering New 

Caledonia and the Fiji Islands. The quality of the game suffered also because several major tactical commanders and their staffs had not had enough time to study 

the plan for the Midway operation.130

After the game concluded on 4 May, two additional days were devoted to study 

and briefings on the operation. Various recommendations to improve the plan 

were made but, for the most part, were rejected. For instance, Kondō suggested 

postponing the operation to allow more time for combat training. Ugaki responded 

that this was impossible unless it was put off for an entire month, or there would be 

not enough moonlight for night maneuvering off the invasion beaches.131

Nonetheless, the war game had revealed many flaws in the plan. Among other 

things, the Combined Fleet’s staff erroneously assumed that the American carriers 

could not reach Midway before it was captured and the Japanese established strong 

air cover. If this condition was not met, disastrous results would follow.132 Another 

problem was inadequate radio communications on the flagship of the First Mobile Force, the carrier Akagi; Yamato had much better communications equipment. Notwithstanding, recommendations that Yamamoto assume direct control 

of Nagumo’s forces were also rejected. Cdr. Minoru Genda (a brilliant officer who 

served on the staff of the First Air Fleet) urged reorganization of the carrier groups. 

Admiral Yamaguchi specifically proposed that the First Mobile Force operate as 

three groups, each consisting of three or four carriers with adequate numbers of 

battleships, cruisers, and destroyers. Combined Fleet Headquarters agreed to this 

proposal in principle but had done nothing by the time the Midway operation was 

executed.133
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On 25 May, a final planning conference for the Midway-Aleutians operation was 

held. Nagumo there informed Yamamoto that his force could not sortie on 26 May—

the carriers needed an extra day to complete their preparations. For this reason the 

pre-invasion air strikes were moved from N–3 (4/3 June) to N–2 (5/4 June). Yamamoto again refused, however, to alter the N-Day or delay the attack on the Aleutians. 

He took a calculated risk that by N–3 the enemy searches from Midway would not 

have reached far enough west to detect Kondō’s Midway Occupation Force.134

The most serious omission in the planning by the Combined Fleet, however, 

was that the senior seagoing commanders—Admiral Nagumo, commander of the 

First Mobile Force, and Admiral Kondō, of the Second Fleet—were not consulted 

at all. The reason was that both fleets were actively engaged in the southern operations until mid-April, and Yamamoto did not want to divert their attention from 

the tasks on hand.135 This was a serious error on the part of Yamamoto and his chief 

of staff, Ugaki; it meant that neither Nagumo nor Kondō had an opportunity to 

provide early input to the plan they would have to execute.

U.S. Command Organization

Adm. Chester W. Nimitz was Commander in Chief, Pacific Ocean Areas 

(CINCPOA)—in modern terms, a theater-strategic commander. As the commander 

of the Northern and Central Pacific Areas (theaters of operations, in modern 

terms), he was also an operational commander. At the time of the battle of Midway, Nimitz was still nominally commander of the Southern Pacific Area, pending 

the arrival of Vice Adm. Robert L. Ghormley, who would arrive on 19 June. As 

the theater commander, Nimitz was in command of all Allied naval, ground, and 

air forces within his area of responsibility and was subordinate to the Joint Chiefs 

of Staff (JCS) in Washington, D.C. In addition, Nimitz was the CINC of the U.S. 

Pacific Fleet (CINCPac), another operational-level command. In that capacity he 

was directly subordinate to Adm. Ernest J. King, who was Commander, United 

States Fleet (COMINCH) / Chief of Naval Operations (CNO). Directly subordinate to Nimitz as CINCPac were the commanders of Northwestern and Hawaiian 

Sea Frontiers and of Patrol Wings, Pacific Fleet / Naval Base Air Defense, as well 

as of a number of seagoing task force commanders (CTFs). The headquarters of 

CINCPOA and CINCPac, the Hawaiian Sea Frontier, and Patrol Wings, Pacific 

Fleet / Naval Base Air Defense, were on Oahu, as were those of the U.S. Army’s 

commanding general (CG) of the Hawaiian Department and the commander of 

the Seventh Air Force.

What the American Commanders Knew

As in the battle of the Coral Sea in early May, U.S. Navy communications intelligence (COMINT) was the most important source of intelligence on the IJN’s plans 

and movements prior to the execution of the Midway-Aleutians operation. In the 

spring of 1942, the U.S. Navy had within the CNO’s office in Washington, D.C., 
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the Radio Intelligence Section (Op-20G), responsible for integrating all COMINT 

on the IJN and for preparing assessments for Admiral King and other senior commanders, including Admiral Nimitz. Also in Washington, in the Office of Naval 

Communications, was a COMINT station code-named NEGAT. In the Pacific 

theater the U.S. Navy operated two COMINT stations, at Pearl Harbor and Melbourne, respectively code-named HYPO and FRUMEL. They provided intelligence 

on the IJN to Admiral Nimitz and Gen. Douglas MacArthur, commander of the 

Southwest Pacific Area, and other high Allied commanders in the theater. American COMINT in the Pacific, however, was handicapped by the loss of the stations 

on Guam and on Corregidor. In addition, the HYPO station was critically short of 

trained operators and analysts, and most of its equipment was obsolete.136

Admirals Nimitz and King were the chief users of the COMINT on the IJN. 

Generally, they were kept current on the whereabouts and pending movements 

of enemy carrier forces. This, in turn, allowed them to deploy U.S. carrier forces 

in a timely way, as the battle of the Coral Sea illustrates. Subordinate task force 

commanders regularly received COMINT from Nimitz. Starting on 17 March, they 

received daily CINCPac Intelligence Bulletins (which replaced CINCPac Combat Intelligence Bulletins) produced by HYPO. Another series, the Radio Digest, produced 

by the commander of the 14th Naval District (COM 14), was usually sent onward 

by CINCPac almost verbatim, as were the COM 14 COMINT summaries.137 Intelligence officers and cryptanalysts worked together to evaluate the texts of decrypted 

messages; the intelligence officers of the various commands then combined radio 

intelligence with combat intelligence information to produce a balanced estimate. 

Nimitz was fortunate to have the services of two outstanding intelligence professionals, Cdr. Joseph J. Rochefort, chief of the HYPO station, and Lt. Cdr. Edwin 

T. Layton, the CINCPac fleet intelligence officer. Layton worked very closely with 

Rochefort in compiling the situation estimates for the CINCPac staff ’s War Plans 

Section. He also briefed Nimitz daily from decrypted intelligence reports, traffic 

intelligence summaries, and any other intelligence sources. Layton had standing 

orders to interrupt Nimitz at any time if he received critical COMINT.138 Each day 

Layton sent the CINCPac Intelligence Bulletin by radio to COMINCH, OpNav (the 

CNO staff), all CINCPac task force commanders, and other high Allied commanders in the Pacific and the Indian theaters. 

Rochefort, for his part, was an ideal combination of intelligence office and 

cryptanalyst. However, he was fiercely independent, and that greatly irritated his 

superior at Op-20G in Washington, Capt. John R. Redman. Rochefort’s relationship with Redman was often acrimonious. Redman wanted each analyst to work 

on a specific and narrow topic, leaving the overall assessment to the Op-20G section. This was not the way Rochefort worked. During the critical weeks preceding 

the battle of Midway, Rochefort’s deductions of enemy intentions were much more 
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accurate than Op-20G’s. But Redman and his brother, Joseph R. Redman, Deputy 

Director of Naval Communications, wanted to show Admiral King how effectively 

they had reorganized naval intelligence.139

By early 1942 Allied cryptanalysts already had evidence of a possible Japanese intention to extend their defensive perimeter beyond the Wake–Marshalls–

Gilberts line. On 5/4 March, Vice Admiral Inoue, commanding the Fourth Fleet, 

launched, as noted above, a minor armed reconnaissance over Oahu, known 

as the K operation. As would be planned again in May, the Japanese used fourthousand-mile-range Kawanishi Type 2 flying boats from Wotje, in the Marshalls, 

some two thousand miles from Hawaii. They landed on French Frigate Shoals, 

about five hundred miles northwest of Hawaii, refueled from a submarine, and 

flew over Oahu, dropping a few bombs for psychological effect.140

The first Japanese reference to Midway, as “AF,” in radio messages appeared on 

4 March 1942. (The A of the digraph indicated the American portion of the Japanese geographic-designator system.) On 13 March American cryptanalysts broke 

a major, headquarters-level Japanese code, known as “JN-25,” and CAST on Corregidor definitely identified “AF” as Midway. The digraph appeared again on 17 

and 25 April in messages broken and translated by FRUMEL and NEGAT. Op-20G 

agreed that AF pertained to Midway but only for communications, not geographic, 

purposes. This interpretation would later cause a great deal of confusion between 

Op-20G and the HYPO station.141

As for the North Pacific, as early as March 1942 there were vague indications of 

possible Japanese operations in the Aleutians. For example, in April, the Second Fleet 

asked for charts of the Gulf of Alaska, the Aleutian Islands, and the Bering Sea.142

In March and April 1942, COMINT provided details of a Japanese redeployment of land-based air units and equipment for the occupation and subsequent 

defense of Midway from homeland bases to the Mandates. On 11 March, Layton 

and Rochefort wrote that the buildup of the Japanese land-based aircraft in the 

Mandates represented a real threat to the U.S. Pacific Fleet in the Central and North 

Pacific. The cryptanalysts warned that the Japanese were planning an attack on 

Midway. However, these warnings were not universally accepted by high naval officials in Washington, who (erroneously) believed instead that the Japanese might 

attack the U.S. west coast at any time.143

In late April and early May, Nimitz was particularly interested in the whereabouts and movements of the strongest enemy surface force, Admiral Kondō’s Second Fleet. That fleet was involved in the search for Vice Adm. William F. Halsey, Jr.’s 

Task Force (TF) 16 between 18 and 25 April. Shortly after 26 April, the American 

analysts located Second Fleet in the northern area, close to Soviet-controlled waters. 

After the 27th the Second Fleet observed radio silence, and the American analysts 

inferred that it would be employed for further action, “possibly in the Aleutians.”144
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On 2 May, a decrypted message from Rear Adm. Kazutaka Shiraishi, the Second 

Fleet chief of staff, to the 5th Base Air Force (part of the Fourth Fleet) in Saipan revealed the Japanese plan to deploy formations referred to as “A Force” and “Striking 

Force” to Truk for a period of about two weeks after 20 June. The sender requested 

that an anchorage be designated for these forces.145 This message actually pertained 

to the Japanese plan to use their fleet to the southward in the aftermath of the 

Midway operation.146

By early May, the IJN’s radio communications activity in the vicinity of Japan had 

been perceptibly increased by exercises conducted by various forces preparing for the 

Midway and the Aleutians operations.147 A radio intercept on 4 May provided an indirect clue that the Japanese planned a major offensive. In that message, the commander 

of the First Fleet informed the commander of Battleship Division (BatDiv) 3 that “these 

ships will be undergoing repairs during the time of the said campaign; work has already 

been started on. . . . The date of completion being [about 21 May], will be unable to accompany you in this campaign.”148 Another intercepted message contained an undated 

anchorage assignment at Truk for the units of the Midway strike force and the Second 

Fleet. Taken together, these two messages created confusion in Washington and Hawaii. 

NEGAT’s analysis inferred the existence of more than one enemy striking force in the 

Central Pacific; it warned that their rendezvous possibly indicated a second phase of the 

Midway operation, possibly involving an attempt to invade Hawaii.149

On 5 May American analysts intercepted a message from Combined Fleet to Tokyo: 

“For currently scheduled operations expedite delivery of fueling hoses for the following units: CruDiv [Cruiser Division] 4, CruDiv 7, DesRon [Destroyer Squadron] 4, 

DesRon [or Destroyer Division (DesDiv)] 8.”150 This message suggested an operation 

that would require underway replenishment. The Japanese were constantly gathering 

weather reports for the northern areas and expressing concern about U.S. Aleutians 

patrols.151

As early as 6 May there were indications that the Japanese were considering operations in the Hawaiian area.152 A radio intercept that day revealed that the Japanese might 

try another K operation in May. The analysts in Melbourne and Hawaii agreed from the 

outset that the Japanese intended to attempt another seaplane reconnaissance of Oahu. 

HYPO explained that K, or “King,” was an abbreviation for “AK”—the Japanese digraph 

for Pearl Harbor.153

HYPO and FRUMEL reported the pairing of CarDivs 1 and 2 for an exercise in the 

Japanese home waters between 3 and 12 May. Another important piece of evidence 

was the HYPO translation of a message sent on 7 May on the agenda for an air commanders’ conference organized by Admiral Nagumo to be held at Kagoshima Bay on 16 

May.154 Among other topics, the conference was to address the battle for air superiority, 

the organization of dive-bombing, torpedo attacks, bombing, and strafing, and methods for long-range and base reconnaissance.155
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On 8 May, Allied COMINT analysts learned about a message to the First Air 

Fleet saying, “DesDiv will be required at Bako [in the Booko Archipelago, Formosa] 

until 20 May and will be unable to participate in your forthcoming campaign. Please 

arrange for some other suitable shift.” Another message, to DesRon 17, revealed the 

task organization of the First Air Fleet: “In accordance with Commander Striking 

Force Operation Order No. 6 screening destroyers are assigned as follows: DesDiv 

. . . to Akagi; DesDiv . . . to Hiei, Kongō, and Hiryū. Akagi departs Yokosuka 15 May; 

Hiei, Kongō, and Hiryū depart Sasebo 21 May; ComDesDiv. . . . [some of its units 

will screen Hiryū.] In company with . . . depart Yokosuka 17 May, rendezvous with 

three units; rendezvous at place near Yokosuka and on 18 June proceed to Sasebo 

operating offensively against submarines en route.”156

On 8 May, HYPO broke and translated a message on the basis of which it correctly associated the First Air Fleet with several Second Fleet elements. The analysts learned that a new striking force, the First Air Fleet, would be led by Admiral 

Nagumo. It would consist of CarDivs 1 and 2, CruDiv 8, and two battleships of 

BatDiv 3. The other major force was Kondō’s Second Fleet.157 The next day, the 

analysts at Melbourne intercepted and translated Order No. 6 of the First Air Fleet, 

which confirmed beyond a doubt that a new carrier striking force had been created. Another radio intercept the same day revealed that a major movement of that 

force would occur on 21 May. Both Rochefort and Layton advised Nimitz that the 

Second Fleet and First Air Fleet were expected to operate in combination at the end 

of May.158

In contrast, Op-20G had little information on then-current Japanese intentions, 

except in connection with the Port Moresby–Solomons operation. In the first week 

of May, radio traffic intercepts indicated that the First, Second, and Fifth Fleets 

might be involved in the new operation. However, the Washington office was in the 

dark about the pending operation’s objectives, precise times, or force composition.159

On 13 May, the Japanese mentioned for the first time the objective of the forthcoming “campaign” (major operation) in a message from an unidentified source to 

chiefs of staff of the Combined Fleet, Second and Fourth Fleets, and the Eleventh 

Air Fleet: “the PS [Saipan] . . . force which is concerned in the occupation of MI 

[later identified as Midway] scheduled to hold an operation conference on the 26th 

and to depart on the 27th; therefore the No. 5 Shima Maru and the . . . should arrive PS [Saipan] by 1200 26th.” The American COMINT analysts were unable to 

comment on this message until 20 May. Yet they were aware on 15 May what the 

Japanese objectives would be.160

On 13 May, the American cryptanalysts decoded two radio messages that provided significant clues about Japanese intentions. In one, a ship requested eight 

charts to be sent to Saipan and held for it. Op-20G quickly identified seven out 

of the eight charts—all of them were for the Hawaiian Islands area.161 The second 
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message directed a freighter, Gosha Maru, to load fuel hoses at Imieji and proceed 

to Saipan. The same message also ordered an air unit to embark its base equipment and ground crews and advance toward “AF” (Midway).162 In addition, and 

on the same day, Allied analysts at Hawaii and Melbourne decoded Second Fleet’s 

Operation Order No. 22, which indicated an interest in the Marianas and also outlined control of units of the Eleventh Air Fleet then being deployed to the SaipanGuam area preparatory to the forthcoming “campaign.” These messages provided 

strong indications that the future offensive would involve Midway and thereby 

reduced concern that the Japanese might attack the West Coast.163

Also on 13 May, Nimitz, on the basis of information obtained by COMINT, 

directed the commander of the Hawaiian Sea Frontier to establish surface patrols 

of the French Frigate Shoals. For this reason the second Japanese K operation, 

planned, as noted above, for the end of the month, would be canceled.164

On 14 May, a radio intercept provided more details about the force composition and objectives of the pending Japanese offensive in the eastern part of the 

Central Pacific. Analysts commented that preparations were being made for offensive operations by a force similar to the one that had attacked Pearl Harbor: 

BatDiv 3, with three or four battleships; CarDivs 1 and 2, with three or four, but 

possibly five, carriers, plus eight destroyers; CruDivs 4 and 8, with four heavy 

cruisers; and DesRon 1, with one light cruiser and twelve destroyers. They also 

noted that the carrier aircraft from at least two carriers (Kaga and Sōryū) and 

probably destroyers were then conducting gunnery exercises in the Sea of Japan.165

On 14 May, on the basis of COMINT, Admiral King issued an estimate of the 

situation considerably different from one he had issued on the 12th. As he had 

in March after the Japanese K operation, he directed Nimitz to declare a state of 

“Fleet Opposed Invasion.” King postulated that the enemy had four options: 

• Attack the Midway–Oahu line in force in the first week of June

• Simultaneously attack the Aleutians chain

• Capture Ocean and Nauru Islands on about 17 May

• Reinforce New Britain / New Guinea and strike southeastward anytime 

between 25 May and 15 June.166 

On 14 May, Nimitz duly declared a state of “Fleet Opposed Invasion” for Hawaii and Midway. This order gave Nimitz full control of all military and naval 

forces in the area. However, Gen. Delos C. Emmons, CG of the Hawaiian Department, challenged Nimitz’s decision to defend Midway, although he was privy to all 

Nimitz’s intelligence. On 25 May he warned Nimitz not to give too much credence 

to reports of Japanese intentions and advised him to rely instead on the enemy’s 

capabilities. (After the battle of Midway, Emmons would apologize to Nimitz.)167

On 15 May, intercepted Japanese messages indicated a concentration of enemy forces in the Saipan area, primarily seaplane tenders. The Kawanishi Type 
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97 flying boats based at Imieji, an intercept suggested, might launch long-range 

attacks on the Hawaiian Islands. In another, DesRon 1 showed interest in fueling arrangements for motorboats in connection with an occupation in the 

Alaska-Aleutians area; that force would depart from a port in northern Japan 

after topping off fuel at Ōminato.168 U.S. Navy radio intelligence reported that 

CINC, Second Fleet had lately been associated with CarDivs 1 and 2, BatDiv 3, 

and numerous destroyer units, “Marus” (freighters), and auxiliaries, suggesting 

that these might constitute a force meant to strike to the southward or toward 

Hawaii. This warning was given three weeks before the battle of Midway.169

On 16 May, radio intercepts revealed that a strong task force in Japanese 

waters was preparing for offensive operations, possibly in the North Pacific. 

They also showed that two weather observation ships (freighters) were in the 

vicinity of Wake and two others east of the Marshalls. Air searches from Japan 

extended out to six hundred miles. Some thirty heavy bombers had arrived in 

Japan from the East Indies. There were indications that Air Squadron (AirRon) 

22, last reported in the Singapore–Indian Ocean area, might return to Japan to 

join the 1st Air Attack Force in operations with the Fifth Fleet. Intelligence reports indicated that submarine operations in northern waters would increase.170

By 16 May, Op-20G and the COMINCH’s War Plans staff, under Rear Adm. 

R. K. Turner, believed that a strong enemy force that was to deploy from Japan in the last week of May 1942 was related to an offensive against northeast 

Australia, New Caledonia, and Fiji starting between 15 and 20 June. A message from King’s headquarters on 15 May, however, shows that his staff did 

not ignore Midway as a possible Japanese objective. The same message also 

incorrectly reported the existence of a second strike force, by associating a force 

assembling in Saipan and scheduled to leave on 24 May with the carrier element of the Northern Strike Force (actually the Northern Area Force). Op-20G 

believed that the objective of that force was possibly to eliminate Midway or 

divert U.S. forces from the South Pacific and from Alaska. The same message 

also suggested that Howland and Baker Islands, rather than Ocean and Nauru, 

might be the enemy objective.171

On 16 May, NEGAT mistakenly warned the War Plans staff in Washington 

that the “K campaign” would be a large-scale attack on Hawaii. Nimitz generally agreed instead with the intelligence analysts at Hawaii and Melbourne. 

In his estimate of the situation the same day, Nimitz stated that the Japanese 

would attack Midway and raid Oahu in the first part of June. He also speculated 

that the enemy bombing of Oahu, using seaplanes, might be delayed until the 

full moon at the end of the month (he probably meant the end of May). Nimitz 

also believed that “unless the enemy is using radio deception on a grand scale, 

we have a fairly good idea of his intentions.”172
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On 17 May, the COMINT analysts learned that two strong task forces were being 

formed in northern waters, comprising BatDivs 1 and 2 (six battleships); CarDiv 

3, with two carriers plus possibly one or two auxiliary carriers, with plane guards 

(destroyers); CruDivs 4 and 7, with four to six heavy cruisers; and DesRon 1, with 

one light cruiser and twelve destroyers. The indications were that all or most of 

these units would depart Japan after topping off fuel at Ōminato. In fact, the CINC 

of the Fifth Fleet had originated a movement report that included CarDiv 3, and 

there were indications that BatDivs 1 and 2 had already departed Kure.173 The same 

day, radio intercepts revealed that the Japanese would commit to the forthcoming 

offensive five large carriers (Kaga, Akagi, Sōryū, Hiryū, and Zuikaku) and one light 

carrier (Junyō). From another message it was learned that submarines “prior . . . will 

be [positioned] 150 miles more or less east of A1 [probably a garble for AF1].”174 On 

17 and 18 May, radio traffic analysts produced several associations of enemy units 

that indicated the makeup of the Aleutian forces.175

On 18 May, radio intercepts revealed that about thirty land-based fighters of 

the 6th Air Group would be loaded on the 22nd on board the carriers of CarDivs 1 

and 2 and then ferried to Midway.176 More details were learned the same day about 

the readiness and pending movements of the enemy forces. BatDivs 2 and 3 were 

believed to be ready to sail soon from Kure. CarDiv 3 was believed to be ready 

for combat. Ōminato was indicated as a possible departure point for operations in 

northern waters. CruDiv 4 was believed to be ready to sail. The status of CruDiv 

7 was uncertain. DesRon 1 was believed to be departing Sasebo between 13 and 

23 May. One of its divisions was reported en route north with CruDiv 5. The Fifth 

Fleet appeared to be closely connected with the operations in hand. BatDiv 3 of 

the Second Fleet, with the possible exception of the battleship Kirishima, would be 

ready on 21 May. The carrier Kaga of CarDiv 1 was now ready and believed actively 

engaged in rehearsals with a target ship. Akagi was reported to have departed Yokosuka 15 May and probably had already joined Kaga. Sōryū, of CarDiv 2, was ready 

to sail, and Hiryū was scheduled to sortie from Sasebo on 20 or 21 May. All the carriers had embarked their planes, with the exception of Hiryū. There were some indications that CruDiv 8 had moved to the Mandates. DesRon 2 was believed ready, 

except that one division might be escorting Shōkaku to home port; this squadron 

would, it was believed, take part in the Midway operation.177

On 19 May, the COMINT analysts obtained further details about the movements of forces assigned to the Midway-Aleutians operation. It was revealed that 

CruDiv 7 would probably operate in the Second Fleet area instead of the First 

Fleet area and that CruDiv 5 might be included in the operations of the Fifth Fleet. 

SubRon 1 and shore-based aircraft of the 6th Air Attack Force would be probably 

employed in conjunction with the Fifth Fleet; AirRon 23 was expected to operate these aircraft. A new unit, DesRon 17, and land-based aircraft of the 14th and 
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Chitose Air Groups would probably operate with the Second Fleet. CruDiv 4, assigned to the Aleutians operation, would arrive at Kure on 19 May and would not 

reach northern Japan until 25 May. CruDiv 5 was scheduled to arrive at Yokosuka 

on 22 May. Armed merchant ships of the Fifth Fleet would be employed as patrol 

vessels in the Aleutians.178

A message decoded on 19 May revealed that CarDivs 1 and 2 would attack Midway for a period of two days (N–2 to N-Day) prior to the landing attempt, from 

a position probably to the northwest of the island. The carrier force commander 

asked to receive weather reports three hours prior to takeoff on the first day of said 

period. On the day of the landing the carrier force would try to reach a point fifty 

miles northwest of Midway before launching its planes as quickly as possible.179

The NEGAT station continued to believe that “AF” was a communications, not 

geographic, designator. In contrast, Rochefort and Layton were still firmly (and 

correctly) convinced that “AF” pertained to Midway. They had recovered some A

designators that equated to the general vicinity of the Hawaiian Islands, so they 

assumed that AF was in the same general area.180 Some analysts in Op-20G argued 

that “AF” referred to Samoa, some believed that it was a geographic designator for 

Hawaii, and others thought that the U.S. west coast would be the next target.181 For 

this reason Rochefort and Layton dreamed up a scheme to trick the Japanese into 

revealing the true meaning of the AF designator—sending a fake radio message 

in plain English stating that the distillation plant on the atoll had broken down (a 

serious matter, because Midway had no other source of freshwater). Layton approached Nimitz, who alone had authority to endorse a deception effort. Nimitz 

agreed to the plan.182 Hence, a message was sent on 18 or 19 May via the cable 

from Honolulu to the commander of the naval base on Midway instructing him to 

send an unencoded message to COM 14 stating, in effect, that his distillation plant 

had suffered a serious casualty and that freshwater was urgently needed; COM 14 

would reply, again not in code, that “water barges would be sent, under tow, soonest.” Japanese intelligence would pick up the messages and disseminate them in the 

daily intelligence reports; these would, in turn, be intercepted by Op-20G, which 

would determine whether a water situation at Midway was mentioned.183

On 22 May, the FRUMEL station published the following translation: “KIMIHI 

(Naval Intelligence Tokyo)—The AF (Midway) air unit sent following radio message to Comdt 14th [Naval] District: ‘AK’ on 20th. ‘Refer this unit’s report dated 

19th, at the present time we have only enough water for two weeks. Please supply 

us immediately.’ Note [by FRUMEL]: Have requested 14th District check this message—if authentic it will confirm identity ‘AF’ as Midway.”184 This message ended all 

controversy about the true meaning of the AF digraph.

On 20 May, the radio intercepts revealed exercises involving two fleets south of 

Japan’s home islands; “Fleet B,” commanded by the CINC of the Combined Fleet, 
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simulated the U.S. Pacific Fleet, while “Fleet A,” under the CINC of the Second 

Fleet, represented the Combined Fleet. The scenario for the exercise was the attack 

on Midway (the Bonin Islands represented Midway). The exercise was conducted 

on 20–22 May.185 On 20 May, Nimitz learned that the Midway Occupation Force 

could sortie from Saipan on 27 May. By estimating its sailing time, he concluded 

that the enemy force would reach Midway on 1 June. 

Another message the same day revealed that the Japanese had changed the AF 

designator to MI (for Midway). By then the American analysts had pieced together 

all the essential elements of the pending Japanese offensive. Nimitz was well aware 

that the Japanese would employ almost their entire Combined Fleet and that he 

would need everything he had to counter their attack.186

In the last week of May, the Japanese radio activity was greatly increased because 

of the intense preparations for the forthcoming operation. COMINT analysts received a large number of messages on the composition of various elements of the 

Combined Fleet and their pending movements. This information was confirmed 

by the appearance of new tactical call signs and by exercise radio traffic that indicated impending movements of forces. This prompted Nimitz to speed up preparations of the Pacific Fleet. The reported movements of enemy ships toward Ōminato 

clearly indicated the assembly of the Northern Force; for this reason Nimitz 

activated Task Force 8. The movements of the enemy Transport Group for Midway 

led Nimitz to issue a series of situation estimates (on 20, 22, 23, and 27 May).187

On 21 May, Allied radio intercepts revealed that the commanders of certain 

forces, believed to be principally seaplane tenders in the Saipan area, would hold a 

conference on 26 May and that their forces would depart the next day. Their exact 

mission was unknown, but fragmentary evidence indicated that it was related to 

deployment of land-based aircraft on Midway after the island was captured.188 Allied analysts also deciphered an outline of the organization of the enemy forces for 

the pending operation against the Aleutians. Ōminato was identified as the main 

base for the forces operating in the northern area.189

On 22 May, British intelligence sent a message to the U.S. Navy providing details 

on the composition of Japanese forces for the pending Midway operation. However, 

the British had no evidence that the Japanese planned to employ their Northern 

Area Force against the Aleutians.190

Nimitz had great confidence in the judgment of his intelligence advisers. He also 

was confident that he had made sound decisions based on the information received 

through COMINT. At the same time, he was very much concerned about his own 

force’s operations security. On 22 May he sent a message to Admirals Halsey (CTF 

16) and Frank Jack Fletcher (CTF 17) ordering them to maintain strict radio silence 

at all times, especially among aircraft about to land; frequent reports showed that 

Japanese COMINT was monitoring air-ground chatter in and out of Pearl Harbor. 
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He also warned General MacArthur that enemy radio intelligence stations were intercepting air-to-ground radio messages between Port Moresby and Allied aircraft. 

MacArthur immediately changed the codes.191

On 23 May, radio intercepts suggested that the carrier Zuikaku was expected to 

have all its replacement aircraft on board by the 28th. It was suspected that Zuikaku

would be assigned to the Northern Area Force. The Fifth Fleet was concentrating in the Ōminato-Kurils area. All or part of AirRon 22 was expected to operate 

from Paramushiro in connection with the shore-based aircraft of the 1st Air Attack 

Force.192

On 24 May, Allied analysts assessed that Saipan had apparently been designated 

the assembly point for the task force assigned to attack Midway. Some units of this 

force were already at Saipan, but many of its major elements were still near Japan. 

At least two battleships of BatDiv 3, possibly all four, were at Ariake Bay, in southeastern Kyūshū. CarDivs 1 and 2 were either in “Empire waters” (Inland Sea) or in 

the vicinity of the Bonins. CruDiv 7 was en route to Saipan. Analysts also noted an 

increase in weather reports from the Mandates area. The enemy intelligence was 

showing increased interest in the patrols by U.S. aircraft in the Hawaii area. All 

available information indicated that attack on and occupation of Midway was the 

objective of the force being assembled at Saipan. However, Allied attention was also 

given to the fact that a force based at Saipan could move with almost equal ease in 

the direction of Australia.193

On 24 May, the Allied analysts obtained more details on the forthcoming 

Aleutians operation. Radio intercepts indicated that assembly of naval forces at 

Ōminato for offensive operations was almost complete; a few light units and auxiliaries were still en route from the Yokosuka area. It was believed that the CINC of 

the Fifth Fleet, on board the heavy cruiser Nachi, would be in general command of 

the northern operations. It was indicated that the movement northward would be 

initiated on 27 May, although the carrier striking force might not leave Ōminato 

until later.194

On 25 May, U.S. COMINT concluded that the Japanese attack on Midway would 

definitely take place on 4 June, while the attack on the Aleutians would start on 3 

June. This assessment was the result of cross-referencing by all three COMINT 

stations in the Pacific theater.195 Despite objections from his own staff, Nimitz accepted Layton’s analysis and decided to base his final timetable on these dates.196

Over the next few days the COMINT stations decoded and interpreted numerous messages that gave the American commanders detailed and accurate knowledge of the composition and pending movements of all the Japanese forces involved.197 For example, on 26 May, Allied COMINT obtained more details on the 

Northern Area Force. In the Ōminato-Kurils area were assembled the CINC of the 

Fifth Fleet (with the flagship heavy cruiser Nachi); CarDiv 3, with one large carrier 
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and one or two auxiliary carriers; CruDiv 4, with two heavy cruisers; DesRon 1, 

with one light cruiser and twelve submarines; SubRon 1, with one tender and eight 

to ten submarines; fifteen armed merchantmen; one or two seaplane tenders; and 

the 6th Air Attack Force, with about thirty heavy bombers. This force was expected to depart Ōminato by 27 May and conduct offensive operations in the eastern 

Aleutians. It would probably proceed northeastward in waters adjacent to the Kurils. Land-based aircraft, probably on Paramushiro, were expected to provide an 

air patrol and possibly eventually to transfer to a base that had been occupied. Possible additions to the Fifth Fleet were Zuikaku, plus plane guards, and CruDiv 5, 

with two heavy cruisers.198

Bad news came on 27 May, when the Japanese introduced a new cipher, called 

“Baker 9” by the American analysts. This rendered unreadable almost all Japanese 

messages intercepted until 5 June. However, the analysts at HYPO were able with the 

aid of RDF to obtain some information on Japanese movements, including those of 

the carrier forces taking part in the Midway and Aleutians operation. Some enemy 

messages continued to be sent in the earlier code (“Baker 8”); these were intercepted 

and read, and they proved to be still valuable in discerning Japanese intentions.199

U.S. Preparations and Plans

The American high naval officials in Washington and Hawaii realized that the 

Japanese would not long remain inactive after their setback in the Port Moresby–

Solomons operation, known in the United States as the battle of the Coral Sea, in 

early May. Preparations and planning for defense of Midway and Hawaii had been 

made, on the basis of the excellent intelligence available to Admirals Nimitz and 

King and other Navy and Army commanders.

Nimitz’s 14 May declaration of a state of “Fleet Opposed Invasion” assigned the 

Navy principal responsibility for repelling that invasion. Yet the Army would have 

overall control over all naval local defense forces specifically assigned by CINCPac, 

as well as all Army forces, except for air units allocated by defense commanders to the 

Hawaiian Sea Frontier for operations over the sea. Nimitz assigned the commander 

of the Hawaiian Sea Frontier responsibility for the defense of Midway itself.200

In mid-May, King and Nimitz had different views about the real objective of 

the pending Japanese offensive. On the basis of the recommendations of his intelligence advisers, King was convinced that the Japanese planned a new advance in 

the southern Pacific.201 After the battle of the Coral Sea, King became unwilling to 

risk the remaining U.S. carriers. He even suggested to Nimitz that carrier aircraft be 

flown ashore to augment land-based aircraft, “in order to preserve our carriers.”202

In contrast, Nimitz argued that carriers should retain their aircraft and be used as a 

mobile reserve. Nimitz was also convinced that the Japanese planned a new offensive in the Central Pacific; he wanted freedom to move his carriers as the situation 

required. Yet in April King ordered Nimitz to keep at least two carriers in the South 
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Pacific. For this reason Halsey’s TF 16 was sent south after the Doolittle Raid on 

18 April. Nimitz became very concerned that he might not be able to timely concentrate his carriers in the Central Pacific. Because of the long distances involved, 

Nimitz required a definite decision; he pressed King on 14 May to reconsider his 

order to keep two carrier groups in the south. 

King procrastinated, not being as certain as Nimitz was that the next Japanese 

move would be against Midway.203 On the 16th, Nimitz decided on his own to recall 

Halsey and so informed King. Nimitz calculated that King’s silence would implicitly endorse his decision; if King disagreed, he would reverse it. In a carefully phrased 

message on 16 May, Nimitz repeated his argument that King’s intelligence analysts 

should reassess their views on the next enemy move in the Pacific. He reassured 

King that Halsey would return to the South Pacific if new information indicated 

that the Japanese offensive would be in that area. After a further discussion with his 

intelligence advisers, who finally concluded that Midway and not the South Pacific 

would be the next target, King changed his mind. On the 17th he sent Nimitz a 

message that he agreed with his decision.204

On 18 May, Nimitz redirected submarines to patrol an area some fifty miles 

northwest of Midway.205 On the 21st he established, as noted above, TF 8, under 

Rear Adm. Robert A. Theobald. He directed Theobald to oppose the enemy advance into the Alaska-Aleutians area. Theobald was to coordinate with the Army 

forces in Alaska (other than the Air Force Alaska Defense Command, under Gen. 

Simon Bolivar Buckner). The Joint Chiefs of Staff directed that Commander of 

the Eleventh Air Force (established on 15 January 1942—formerly the Alaskan Air 

Force, established on 28 December 1941) Gen. William O. Butler would command 

all U.S. Army and Navy air units in Alaska and would report directly to Theobald.206

As has been seen, the preparations of the U.S. Pacific Fleet for the forthcoming defense of Midway/Hawaii and the Aleutians greatly accelerated when Nimitz learned 

from radio intercepts the precise dates of the planned Japanese attack. On 26 May, 

Halsey’s TF 16 returned to Pearl Harbor and immediately began preparations for 

the battle. CINCPac Intelligence Bulletin No. 72 on 26 May informed task force commanders, including Admiral Theobald, that the Japanese northern force had begun 

to depart from Ōminato. COM 14 published an assessment the same day that all 

enemy carriers were at sea.207

On 30 May, Nimitz informed CG of the Hawaiian Department and Commander, Patrol Wing Two that Commander, Naval Base Air Defense had authority to order Army bombers on missions, including basing them on Midway. Commander, Task Force 9, who was also Commander, Patrol Wings, Pacific, now had 

operational control of all Navy reconnaissance planes except those on Midway 

and Johnston Islands and over specifically assigned Army bombers based on Oahu, 

including the Seventh Bomber Command.208
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Upon the arrival of TF 16 Nimitz received the bad news that Halsey had fallen 

very ill and had to be hospitalized. He had counted on Halsey, as the most experienced and aggressive carrier admiral, to be in charge of all carriers for the 

forthcoming operation. Halsey’s logical replacement would be Rear Adm. Leigh 

Noyes. However, Halsey insisted, to Nimitz’s surprise, that Rear Adm. Raymond 

A. Spruance, his cruiser group commander, replace him instead. Spruance was in 

Halsey’s view the only flag officer to whom he could entrust command of two carriers. Halsey recommended that Spruance retain Halsey’s entire staff, except for 

the flag aide. Nimitz did not know Spruance personally but had heard of his superb reputation as a strategist. Spruance was also known to be calm and to ponder 

deeply before making a decision. Nimitz agreed with Halsey’s recommendation, 

and Spruance became the new CTF 16.209

Spruance’s chief of staff was Capt. Miles R. Browning, who had served under 

Halsey. Browning was an experienced aviator but was very unpopular among the 

aviators, because of his bad temper. He was emotionally unstable, often angry and 

excited, and (when off duty ashore) drank too much. Browning was also a poor 

administrator.210

Fletcher and his TF 17 with damaged Yorktown arrived at Pearl Harbor in the 

afternoon of 27 May. The damage to Yorktown was so extensive that it was estimated 

that at least several weeks would be required to make it ready for operations.211 Some 

estimates were that repairs would take ninety days. But Nimitz wanted Yorktown to 

be ready for combat in forty-eight to sixty hours;212 Nimitz directed the navy yard to 

complete the necessary repairs by 30 May.213 After extraordinary efforts, Yorktown

was ready for sea as Nimitz requested.214

Theobald arrived in the Aleutians on 27 May. The state of “Fleet Opposed Invasion” gave Theobald command over all U.S. forces in the Alaska-Aleutians 

theater.215 He was informed that American intelligence believed that the enemy forces 

for the Aleutians included one group destined for Kiska and another possibly for 

Attu. Nimitz also alerted Theobald that enemy heavy bombers would be based on 

Paramushiro. Yet Theobald did not believe the intelligence, provided by both the Hawaii and Melbourne COMINT centers. He decided to deploy his forces about four 

hundred miles south of Kodiak to prevent the enemy from getting between him and 

the eastern Aleutians and Alaska.216 That unsound decision would render Theobald’s 

forces unable to prevent the subsequent Japanese occupations of Kiska and Attu.

Nimitz issued his Operation Plan 29-42 on 27 May 1942. The plan, only about ten 

pages long, reflected the command style of King and some other admirals—it told 

subordinates what needed to be done, gave them the necessary resources, provided as 

much information on the enemy as possible, and then let them alone to accomplish 

their assigned missions. (King was known to dress down commanders for oversupervising subordinates with excessively complex and detailed directives.)217
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Nimitz stated in Operation Plan 29-42 that the enemy was expected to attempt to 

capture Midway in the near future, employing a force of two to four battleships, four 

to five carriers, eight to nine heavy cruisers, sixteen to twenty-four destroyers, and 

eight to twelve submarines, plus a landing force with seaplane tenders. The attack on 

Midway might be preceded or followed by an attack on Oahu.218 He estimated that the 

enemy action would be a full-scale attack, aimed at the quick occupation of Midway 

for use against the Hawaiian area. The enemy operation could start as soon as 30 May. 

From the COMINT reports Nimitz believed that the enemy would conduct a 

preliminary reconnaissance by submarines, then a high-speed approach by carriers; a preliminary attack by carrier aircraft would begin at daylight or during 

moonlight and continue for about two days, or until defending air forces had been 

eliminated. He estimated that for this purpose one or more enemy carriers might 

closely approach the island in daylight, from a northwesterly direction. The attack 

on Midway would be very intense, so as to prevent the island from refueling and 

rearming aircraft—a task that might be complicated at night by gunnery bombardments. The attacking enemy carriers would be shielded from attack. The enemy 

would probably carry out the landing on Midway at night and, if it were successful, would bring in aircraft, motor torpedo boats (MTBs), and base equipment. 

The enemy would concentrate submarines in the vicinity of Midway and some two 

hundred miles west of Oahu. If the U.S. carriers were detected early in the operation, they would become the primary attack objective of the Japanese carriers.219

Nimitz considered employing Task Force 1, based at San Francisco, in the pending operation but decided against it. TF 1 did not have an adequate force of destroyers and cruisers to protect against surface forces and aircraft. Nimitz also did not 

want to reduce the screen for the carrier forces.220 Yet for some reason he decided 

to assign five cruisers and four destroyers to the North Pacific Force (TF 8).221 (This 

decision was perhaps unsound, because it was far more critical to strengthen the 

defenses of the carrier striking forces—the U.S. operational center of gravity—than 

those of the Aleutians. Nimitz was well aware of the large force the Japanese had 

assigned in the north. He simply lacked sufficient combat strength to match the 

Japanese superiority in carriers, battleships, and other large surface combatants in 

the Aleutians area.)

Nimitz intended to employ only forces with long-range striking power. A fast 

carrier striking force would comprise three carriers (Enterprise, Hornet, and Yorktown) and provisionally a fourth (Saratoga), from TF 11 (then in San Diego, under 

Rear Adm. Aubrey W. Fitch) if it arrived in time. Nimitz’s intent was to use longrange search aircraft to detect the enemy early and then to attack it with his carrier 

striking force. All available submarines would be stationed along the approaches 

to Midway and Oahu, both to detect the approaching enemy and support the carrier striking force in case of withdrawal. Nimitz planned to have on Midway the 
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maximum number of land-based aircraft that could be accommodated. Additional 

ground forces would be provided for the garrison, plus more gun batteries and 

mechanized equipment, MTBs, and patrol craft. Nimitz decided to position his 

carrier striking force northeast of Midway and thereby occupy a flanking position against enemy forces coming from the northwest.222 Also, this position was 

favorable for intercepting the Japanese forces approaching either Midway or the 

Aleutians. This was based on the timely and accurate communications intelligence 

he had obtained by the COMINT.

Nimitz organized his forces (see sidebar 2) into the Striking Force (TF 16 and 

TF 17), TF 1 (Battleships), TF 7 (Submarine Force), TF 9 (Patrol Wings, Pacific /

Naval Air Base Defense Force), the Hawaiian Sea Frontier Forces, and TF 8 

(North Pacific Force). The Striking Force, under Fletcher, consisted of two carrier task forces, TF 17 (under Fletcher) and TF 16 (under Spruance). Nimitz stated 

in his operation plan that the availability of TF 17 as a unit would depend on the 

condition of Yorktown (then undergoing repairs). If Yorktown were not available, 

instructions would be issued regarding the employment of the remainder of the 

task force.223

Nimitz directed the Striking Force to hold Midway and “inflict maximum 

damage on enemy by employing strong attrition tactics.”224 He wrote, “We must 

endeavor to reduce his forces by attrition-submarine attacks, air bombing, attack 

on isolated units. . . . If attrition is successful the enemy must accept failure of his 

venture or risk battle on disadvantageous terms for him.”225

This emphasis on “attrition” was reportedly a result of direction by Admiral 

King. The term was poorly chosen; what Nimitz really described was the employment of diverse combat arms, or “combined-arms tactics,” not force-on-force or 

attritional tactics. Normally, an inferior force should avoid attrition as a tactic 

when confronting a much stronger enemy, because it lacks a margin of numerical 

strength ultimately to prevail. In a separate letter of instruction to Fletcher and 

Spruance Nimitz wrote, “In carrying out the task assigned in op plan 29-42 you 

will be governed by the principle of calculated risk, which you will interpret to 

mean the avoidance of exposure of your force to attack by superior enemy force 

without prospect of inflicting, as a result of such exposure, greater damage to the 

enemy.”226 They were also directed not to “accept such decisive action as would be 

likely to incur heavy losses in our carriers and cruisers.”227

The Striking Force would take up its position northeast of Midway on 30 May. 

The intent would be to obtain initial advantage against the enemy carriers attacking the island. TF 16 would depart from Pearl Harbor on 28 May; other forces 

would join TF 16 as directed by Nimitz. Oilers would depart in company with 

TF 16 and “operate as ordered by senior Striking Force commander in area of 

Continued on page 126
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U.S. Task Organization

Striking Force: Rear Adm. Frank J. Fletcher

Task Force 17 (Rear Adm. Fletcher)

TG 17.5 (Carrier Group) 

Yorktown (27 F4F-4 Wildcat fighters, 19 SBD-3 bombers, 18 SBD-3 bombers, 15 TBD-1 

Devastator torpedo bombers)

TG 17.2 (Cruiser Group, Rear Adm. William W. Smith)

Astoria 

Portland 

TG 17.4 (Destroyer Screen, Capt. Gilbert C. Hoover, Commander, DesRon 2)

DesRon 5 (Hammann, Hughes, Morris, Anderson, Russell)

DesDiv 22 (Gwin, en route to TF 16, joined TF 17 on 5 June 1942)

Task Force 16 (Rear Adm. Raymond A. Spruance)

TG 16.5 (Carrier Group) 

Enterprise (27 F4F-4s, 18 SBD-3 observation planes, 19 SBD-2/-3 bombers, 14 TBD-1s)

Hornet (27 F4F-4 Wildcats, 16 SBD-3 observation planes, 19 SBD-3 bombers, 18 TBD-1 torpedo 

bombers)

TG 16.2 (Cruiser Group, Rear Adm. Thomas C. Kinkaid)

New Orleans, Minneapolis, Vincennes, Northampton, Pensacola, Atlanta 

TG 16.4 (Destroyer Screen, Capt. Alexander R. Early, Commander, DesRon 1)

DesRon 1 (Phelps, Worden, Monaghan, Alywin)

DesRon 6 (Balch, Conyngham, Benham, Ellet, Maury)

Oiler Group

2 Oilers (Cimarron, Platte)

2 Destroyers (Dewey, Monssen)

Task Force 1: Vice Adm. William S. Pye

Carrier Group

2 Battleships (Pennsylvania, Tennessee) 

1 Auxiliary Aircraft Cruiser (Long Island—12 SOCs, 7 F4F-4s)

Battleship Division 3 (Idaho, New Mexico, Mississippi)

Battleship Division 4 (Maryland, Colorado)

Destroyer Screen

8 Destroyers (Craven, Dunlap, Fanning, Aaron Ward, Cushing, Porter, Drayton, Dale)

Task Group 11.1 (Capt. Dewitt C. Ramsey)

1 Carrier (Saratoga—1 SBD-3 Dauntless, 13 F4F-4 Wildcats, 22 SBD-3 Dauntlesses)

1 Light Cruiser (San Diego)

4 Destroyers (Mahan, Smith, Preston, Laffey)

Task Force 7 (Submarines): Rear Adm. Robert H. English, Commander, Submarine Force 

Pacific, Pearl Harbor

TG 7.1 (Midway Patrol Group)

12 Submarines (Cachalot, Flying Fish, Tambor, Trout, Grayling, Nautilus, Grouper, Dolphin, Gato, 

Cuttlefish, Gudgeon, Grenadier) 

TG 7.2 (Support Group [“Roving Short-Stops”])

3 Submarines (Narwhal, Plunger, Trigger)

TG 7.3 (North of Oahu Patrol)

4 Submarines (Tarpon, Pike, Finback, Growler)

Patrol Wings Pacific / Task Force 9 (Naval Air Base Defense Force), Pearl Harbor: Rear Adm. 

Patrick N. C. Bellinger

Patrol Wing 1 (VP-11, VP-12, VP-14, VP-72, VP-91)

Patrol Wing 2 (VP-23, VP-24, VP-44, VP-51)
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Hawaiian Sea Frontier, Pearl Harbor: Rear Adm. David W. Bagley

(Midway Local Defenses)

Midway Naval Air Station, Capt. Logan C. Ramsey, Commander

Sand Island Seaplane Base (14 PBY-5s, 11 search aircraft)

Eastern Island Airfield, Naval Air Station Utility (1 J2F-2)

Marine Aircraft Group 22 (2nd Marine Air Wing)

VMF-221 (21 F2A-3 Buffalo; 7 F4F-3 Wildcats)

VMSB-241 (19 SBD-2 Dauntlesses, 21 SB2U-3 Vindicators)

Patrol Wing 2, Detachments

VP-23 (14 PBY-5 Catalinas)

VP-24 (3 PBY-5A Catalinas)

VP-44 (8 PBY-5A Catalinas)

VP-51 (3 PBY-5A Catalinas)

Patrol Wing Reinforcements (30 PBYs)

Seventh Army Air Force, Detachments (22 B17E Flying Fortresses, 4 B-26B Marauders)

Torpedo Squadron 8, Detachment (6 TBF-1 Avengers)

Midway Local v Ground Defenses (Capt. Cyril T. Simard, USN)

6th Marine Defense Battalion (reinforced), Fleet Marine Force

3rd Marine Defense Battalion 

3rd Marine Raider Battalion, AA and Special Weapons personnel

2nd Marine Raider Battalion, Company “C” (Sand Island)

2nd Marine Raider Battalion, Company “D” (Eastern Island)

22nd and 23rd Provisional Infantry Companies

Motor Torpedo Boat Squadron 1 (8 MTBs—PT 20, PT 21, PT 22, PT 24, PT 25, PT 26, PT 27, PT 28)

(Deployed in the Hawaiian Archipelago)

Kure

2 MTBs (PT 29, PT 30)

4 Small Patrol Craft

French Frigate Shoals

1 Seaplane Tender (Thornton)

1 Destroyer Tender (Ballard)

1 Destroyer (Clark)

Pearl and Hermes Reef

1 Oiler (Kaloli)

Crystal (PY 25, converted yacht)

1 Tug (Vireo)

Lisianski

YP 284 (converted tuna boat)

Gardner Pinnacles

YP 345

Laysan

YP 290

Necker Island

YP 350

Midway Relief Fueling Unit

1 Oiler (Guadalupe)

2 Destroyers (Blue, Ralph Talbot)

North Pacific Force (Task Force 8): Rear Adm. Robert A. Theobald

TG 8.6 (Main Body, Rear Adm. Theobald)

2 Heavy Cruisers (Indianapolis, Louisville)

3 Light Cruisers (Nashville, St. Louis, Honolulu)

DesDiv 11 (4 destroyers—Gridley, McCall, Gilmer, Humphreys)

TG 8.1 (Air Search Group)

20 PBYs (Patrol Wing 4), 1 Army Air Forces B-17, on 2 destroyer seaplane tenders 

(Williamson—4 PBY-5As; Gillis—12 PBY-5As) and 1 small seaplane tender (Casco—4 

PBY-5As)
J

operations.”228 All the submarines were to reach their assigned stations by the 

morning of 3 June.229 TF 7 was tasked to “inflict maxim damage to enemy.” The 

priority of targets was carriers, battleships, transports, cruisers, and auxiliaries.230

The commander of the Patrol Wings, Pacific was directed to deploy aircraft to 

Midway and Johnston Island. They would be subordinate to the naval air station 

commander (CNAS) on Midway. One patrol-plane tender would be deployed at 

French Frigate Shoals. The commander of the Hawaiian Sea Frontier was to obtain 

early information of the enemy forces by conducting daily air searches with the 

maximum number of planes available and out to the maximum practicable radius 

from Midway. He was to inflict maximum damage on the enemy, particularly on 

carriers, battleships, and transports, and to protect his forces on the ground. Forces 

on Midway should be withdrawn to Oahu if necessary to avoid their destruction.231

The U.S. command-and-control arrangement for the forthcoming defense of 

Midway was clear and straightforward. Broad tactical direction of all forces in the 

Midway area was retained by Nimitz. He allowed freedom of action to the carrier task forces commanders and CNAS Midway. TF 16 and TF 17 operated under 

Fletcher, whose immediate superior was Nimitz.232 After TF 16 and TF 17 sailed 

out from Pearl Harbor, Nimitz was able to communicate with each commander 

but they were unable to communicate with him without revealing their positions 

to the enemy. Fletcher and Spruance had full freedom to decide when to launch 

their air strikes and when to advance or withdraw from their assigned positions in 

TG 8.2 (Surface Search [Scouting] Group)

1 Gunboat (Charleston)

1 Oiler (Oriole)

5 Coast Guard Yard Patrol Vessels (Haida, Onondaga, Cyane, Aurora, Bonham)

14 District Patrol Vessels

TG 8.3 (Air Striking Group, Brig. Gen. William O. Butler)

21 P-40s, 12 B-26s, 2 B-18s (Fort Randall, Cold Bay)

12 P-40s (Fort Glenn, Umnak)

15 P-39s, 17 P-40s, 5 B-17s (Kodiak)

25 P-38s, 15 P-39s, 4 P-36s, 7 B-17s, 5 B-18s, 12 B-26s, 2 LB-30s (Anchorage)

Pursuit Squadrons 11, 18, 54 (Army—50 P-40s, 25 P-38s)

Bomber Squadrons 36, 77 (Army—12 B-36s, 5 B-17s)

Bomber Group 28 (Army—14 B-26s)

Fighter Squadron 12 (12 F4Fs)

Canadian fighter squadron (30 fighters)

Canadian reconnaissance squadron (15 aircraft)

TG 8.4 (Destroyer Striking Group, Commander, DesDiv 6)

9 Destroyers (Case, Reid, Brooks, Sands, Kane, Dent, Talbot, King, Waters) 

TG 8.5. (Submarine Group)

SubDiv 41 (S-18, S-23, S-27, S-28, S-34, S-35)

TG 8.9 (Tanker Group)

2 Oilers (Sabine, Brazos)

SS Comet

Sources: Bates, Battle of Midway, pp. 244–46; Morison, History of United States Naval Operations in World War II, vol. 4, 

pp. 87–93, 172–74.
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the vicinity of Midway. Their forces were able to communicate internally prior to 

combat only via visual signals.233

On 28 May, Nimitz alerted all subordinate commanders that the deployment of 

the Japanese striking forces was under way. He directed Spruance and his TF 16 to 

the area northeast of Midway. Air searches from Midway intensified significantly 

after 30 May. On average, twenty patrol aircraft at a time conducted searches as far 

as seven hundred miles from Midway.234 Several patrol planes conducted searches 

from Johnston Island out to five or six hundred miles.

In his Operation Order 28-42, issued to Admiral Theobald on 27 May, Nimitz 

directed TF 8 to operate in the North Pacific against an expected attack in the 

Aleutians.235 He stated that there were indications that the Japanese had completed 

plans for an amphibious landing to secure an advance base in the Aleutian Islands, 

the attempt to commence in late May 1942. The enemy force consisted of CarDiv 

3 (Ryūjō, plus one or two other carriers); one heavy cruiser (Nachi, flagship of the 

CINC of the Fifth Fleet); one to three heavy cruisers; a section of CruDiv 4, with 

two heavy cruisers; two light cruisers; DesRon 1 (less one destroyer division) plus 

DesDiv 2, with sixteen destroyers; and SubRon 1, with eight to ten submarines. 

The above-listed forces were estimated to have arrived at northern Japan on 25 

May, to refuel and proceed to the Aleutians. They would probably cover and escort 

a group of transports, landing-craft carriers, seaplane tenders, cargo vessels, and 

tankers. It was expected that some small auxiliary patrol vessels would conduct reconnaissance and patrols in the Aleutians.236 (This estimate was reasonably correct 

regarding the number of and types of combatants that took part in the early phase 

of the Aleutians operations, but the actual deployment date was 23, not 25, May. 

The remainder of the Japanese force for the Adak and Kiska occupation departed 

Ōminato on 27 May.)237

Nimitz’s orders on 27 May to Theobald were accompanied by a comprehensive assessment of the enemy Northern Area Force and its preliminary timetable. Theobald, 

however, treated that valuable report (and its subsequent refinements containing 

more detail on the timing and plan of the enemy attack) as the product of Japanese 

deception and refused to include it in his plans.238 Instead, he made his own (and 

erroneous) assumptions on the situation. Among other things, he believed that the 

Japanese intended to seize bases in the Unimak–Dutch Harbor–Cold Bay area, with 

Kodiak-Kenai as a further objective. The enemy’s first move, he thought, would be a 

surprise bombing and strafing attack against airfields within supporting distance of 

selected landing sites.239 Theobald planned to defend the Unimak–Dutch Harbor–

Cold Bay area by timely detecting enemy surface forces with long-range aircraft and 

picketboats (small cutters and converted fishing vessels). All available bombers based 

at Fort Glenn, Fort Randall, and Cold Bay would be employed against enemy ships. 

A force of destroyers based at Makushin Bay, on Unalaska Island, would be employed 
J

as a “weapon [of] opportunity.” He aimed to deploy a force of cruisers plus several 

destroyers at the southern approaches to Kodiak. Fighters based at Fort Glenn would 

be used for the defense of Dutch Harbor.240

Theobald had many difficulties in organizing the defense of the Aleutians. His 

forces were clearly inadequate for the task. They were not only small but had to 

be deployed over a large part of the theater, and he could not expect reinforcements.241 In any case, he had insufficient naval forces and land-based aircraft to 

oppose two Japanese light carriers.242 Theobald had to rely on Catalinas and Army 

pursuit planes to detect the enemy approaching the Aleutians. Some twelve out 

of his twenty PBYs were at Dutch Harbor; the Army planes, however, were maldeployed. General Butler, commander of the Eleventh Air Force, objected to deploying them at Kodiak and Anchorage and wanted to leave unoccupied the two 

westernmost Army airfields, at Cold Bay and Otter Point, on Umnak (in the Fox 

Islands group). Theobald was opposed to that. He finally persuaded Butler to send 

60 percent of his planes to the two westernmost bases, from where they could support naval forces in defense of Dutch Harbor.243

On 27 May, Theobald issued an operational plan in which he stated (wrongly) 

that the enemy attack could be expected in the first few days of June, probably 

in the Unimak–Dutch Harbor–Cold Bay area.244 Theobald decided to deploy his 

main body some four hundred miles due south of Kodiak, where he could defend the eastern Aleutians and Alaska.245 This decision clearly contradicted the 

intelligence Nimitz had provided to him on the Japanese intention of capturing 

islands in the western Aleutians. In this way Theobald made the main body of TF 

8 irrelevant in the pending operation. 

Theobald ordered daily searches to start on 28 May from the three westernmost Army airfields to a distance of four hundred miles and from Kodiak out to 

seven hundred miles. In addition about twenty picket ships would be deployed 

south of the Aleutians and in the Bering Strait approaches to Dutch Harbor. 

Theobald planned to have these pickets on station by 3 June. However, several 

cutters were too far away to arrive in time and others were too unseaworthy to 

remain on station.246

The Correlation of Forces

The Japanese had overwhelming superiority over the U.S. forces in both the 

Midway and the Aleutians operations. Yamamoto commanded a fleet more than 

twice the size of the U.S. forces opposing him.247 The Japanese had four (versus 

three) large carriers and two (versus none) light carriers. They had 215 aircraft 

on board their large carriers (seventy-three fighters, seventy dive-bombers, and 

seventy-two torpedo bombers).248 The three Japanese light carriers had ninetythree aircraft (forty-six fighters, fifteen dive-bombers, and thirty-two torpedo 

bombers).
J

The United States had 187 combat aircraft on board its large carriers (seventynine fighters, sixty-seven dive bombers, and forty-one torpedo bombers—this 

number did not include thirty-two observation dive bombers). In addition, the 

Americans had on Midway sixty-eight Marine aircraft (twenty-eight fighters and 

forty dive-bombers), thirty-four Navy aircraft (twenty-eight patrol aircraft and six 

torpedo bombers), and four medium and nineteen Army long-range bombers. 

In the Midway operation, the Japanese had absolute superiority in battleships 

(seven versus none). The Americans were also inferior in the number of heavy 

cruisers (eight versus ten), light cruisers (none versus ten), and destroyers (seventeen versus forty-six). The Japanese had a greater number of 4.7- and six-inch guns 

on board their surface ships. The Americans had more aircraft on board cruisers 

(twenty-eight to fourteen).249 Both sides had assigned to the operation the same 

number of submarines (nineteen to nineteen). 

For the Aleutians operation the Japanese had assigned two light carriers, three 

heavy cruisers, four light cruisers (plus two auxiliary light cruisers), and thirteen 

destroyers. However, their superiority was potentially much greater because the 

Guard Force (four battleships, two light carriers, twelve destroyers) could be employed in the support of the Aleutians operation. In contrast, TF 8 had only two 

heavy and three light cruisers and thirteen destroyers. The Americans had a slightly larger number of submarines (six versus five).

The Japanese had a more balanced carrier force. Their carrier aircraft were of 

nearly homogeneous design. The Zero fighters were superior to their American counterparts. The Japanese dive-bombers were highly effective. The Japanese pilots were 

superb;250 they also had much more combat experience than the American pilots. 

The major weaknesses of the Japanese were inferior intelligence information, 

lack of radar and automatic aircraft-homing equipment, an inadequate number of 

heavy AA machine guns, poorly armored or no self-sealing tanks on aircraft, and 

limited land and air reconnaissance from Wake Island.251 The Japanese radio gear 

was technically much inferior to U.S. equipment.

Among the U.S. advantages was the use of radar for fighter direction. American 

aircraft were fitted with self-sealing fuel tanks and armor. U.S. ships had technically superior radio equipment, and their communications with shore commands 

were more reliable, because of the shorter distances involved. Many U.S. ships and 

aircraft were equipped with radar. The American weaknesses included inability to 

concentrate aircraft and fighter defense due to the separation of independent carrier groups, using different cruising instructions. Also, TF 16 and TF 17 had never 

operated together. The Yorktown air wing was a composite formed of aircraft that 

had been assembled from three carriers and had never operated together. U.S. carrier aircraft generally lacked homogeneity in speed and range. The performance of 
J

American fighters was inferior to that of the Zero. The U.S. torpedo bombers were 

slow, and their torpedoes were not as effective as their Japanese counterparts.252 The 

U.S. Striking Force had an insufficient number of AA heavy machine guns.

Perhaps the greatest American advantage was surprise—the Japanese did not 

expect the U.S. carriers to be in the area prior to the planned landing on Midway. Also, the Japanese ships and submarines operated from an exterior position 

and had to transit much longer distances from their bases to the operating areas. 

This, in turn, meant not only much longer transit times but also great logistical 

difficulties. In contrast, the U.S. Striking Force occupied a central position and was 

interposed between the First and Second Mobile Forces. It operated along divergent and short lines of operation. It was near a major fleet base, and its logistical 

support was much simpler than that for the enemy forces. For example, the lines of 

operation for the First Mobile Force and main body stretched 2,300–2,400 nautical 

miles from their bases to the operating area northwest of Midway. In contrast, lines 

of operation for the U.S. Striking Force from Pearl Harbor to the operating area 

were between a thousand and 1,100 nautical miles. In the north, the Second Mobile 

Force had to steam about three thousand nautical miles from Ōminato to a position some four hundred miles south of Dutch Harbor, while TF 8 operated along 

lines of operation only several hundred miles long.

Deployment of the Opposing Forces

The Japanese forces that took part in the Midway operation deployed from basing 

areas in the Inland Sea and Central Pacific (see maps 7 and 8). In the early evening 

of 26 May, Nagumo’s First Mobile Force left Hashirajima Anchorage in Hiroshima 

Bay. Yamamoto’s Main Force also departed Hashirajima on the 26th. It sailed eastward to the position 35° north, 165° east longitude, where the Guard Force was 

detached at about 1500 on 3 June.

The Midway Occupation Force left the Saipan-Guam area in several separate 

groups. The Minesweeping Group departed on 25 May. This group was followed on 

the night of the 27th by the Transport Group, Close Support Group, and Seaplane 

Tender Group. Kondō’s main body sortied from Hashirajima during the morning 

of 28 May.253 Most of the submarines taking part in the Midway operation proceeded to Kwajalein Atoll, arriving about 10 May; two submarines had to return 

home because of engine troubles, and one returned owing to the illness of its commanding officer. The three boats of SubDiv 13 completed repairs by early May and 

arrived at Kwajalein about the 20th. SubRon 5 and the tender Rio de Janeiro Maru

departed for Kwajalein on 16 May and arrived there the end of the month.254

The forces assigned for the Aleutians operation deployed from their bases 

in northern Honshū and the Kurils. The Northern Area Force, Main Body, left 

Ōminato on 25 May, setting a course toward the area southeast of Attu. At noon 

on 26 May, the Second Mobile Force sortied from Ōminato on easterly and then 
J

KAMCHATKA

Petropavlovsk

Hakodate

HOKKAIDŌ

Ōminato

Tokyo

Yokosuka Kure

HONSHŪ

Vladivostok

BUNGO

STRAIT

IWO JIMA

SAIPAN

GUAM

S E A O F

O K H O T S K

KURIL ISLANDS

MARSHALL ISLANDS

WAKE

ISLAND

ENIWETOK

JOHNSTON ISLAND

HAWAII

OAHU

KURE

MIDWAY

A L E U T I A N I S L A N D S

KOMANDORSKIISLANDS

ATTU

KISKA

AMCHITKA ADAK

Otter

Point

DUTCH

HARBOR UMNAK KODIAK

Vancouver

Seattle

YAP

CAROLINE ISLANDS

TRUK

PONAPE

WOTJE

KWAJALEIN

JALUIT

HiroshimaNagasaki

CHRISTMAS ISLAND TARAWA

SanFrancisco

BONINISLANDS Kagoshima

Sakhalin Paramushiro

MARCUS

ISLAND

MARIANAS

2400

3

KISKA OCCUPATION FORCE

2400

3 1500

2 1500

1 1500

31 1500 30

700 MI.

700 MI.

ADAK-ATTU OCCUPATION FORCE 1500 “TEI” LINE

2

2400

3

PATROL

VESSELS

11

PATROL

VESSELS

400 MI.

400 MI.

400 MI.

400 MI.

0400

27

0800

29

0700

27

2400

3

0900

1

0700

2

0700

1

1400

31

2400

3

0900

2

0900

31

TG 8.6

0500TG 8.6

TU 1.1.4

2400

3

TG 11.1

1000

31

1000

2

TU 8.1.4

1000

1

“OTSU” LINE

“HEI” LINE

“KO” LINE

700 MI.

500 MI.

800 MI.

800 MI.

TF-17

TF-16 3-SS

2400

3

TFs 16 & 17

1600

2

1000

30

0900

31

1000

29

SECOND MOBILE FORCE

700 MI.

FIRST MOBILE FORCE

MAIN BODY

MAIN

FORCE

1500

29

0300

31

0300

2

1500

3

2400

3

2400

1500

3

1330

3

1500

3

2400

3

1400

2

1-SS 0000

2 1500

1

1500

31 600 MI.

1050 MI.

700 MI.

2400

3

2400

3

SEAPLANE

TENDER

GROUP

MINESWEEPING GROUP

MIDWAY

FORCE

OCCUPATION

= U.S. Forces= Japanese Forces=

LEGEND

1000

1

HOUR

DAY

160° 180° 160° 140° 140° 130° 135° 145° 150° 155° 165° 170° 175° 175° 170° 165° 155° 150° 145° 135° 130° 125°

160°E 180° 160°W 140°W 140°E 130°E 135°E 145°E 150°E 155°E 165°E 170°E 175°E 175°W 170°W 165°W 155°W 150°W 145°W 135°W 130°W 125°W

60°N40°N20°N45°N50°N55°N35°N25°N30°N15°N10°N

 5°N

60°40°20°45°50°55°25°30°15°10°

 5° 0

50

100

150

200

250nm

MAP 3: MOVEMENTS OF THE OPPOSING FORCES AND SEARCHES UNTIL 2400, 3 JUNE 1942

Map 7

Movements of the opposing 

forces and searches until 

2400, 3 June 1942
J

KAMCHATKA

Petropavlovsk

HOKKAIDŌ

Ōminato

Tokyo

Yokosuka Kure

HONSHŪ

Vladivostok

BUNGO

STRAIT

IWO JIMA

SAIPAN

GUAM

S E A O F

O K H O T S K

MARSHALL ISLANDS

WAKE ISLAND

ENIWETOK

JOHNSTON

ISLAND

HAWAII

OAHU

FRENCH FRIGATE SHOALS

KURE

MIDWAY

A L E U T I A N I S L A N D S

KOMANDORSKIISLANDS

ATTU

KISKA

AMCHITKA

ADAK

Otter

Point

DUTCH

HARBOR UMNAK KODIAK

Vancouver

Seattle

YAP

CAROLINE ISLANDS

TRUK

PONAPE

WOTJE

KWAJALEIN

JALUIT

HiroshimaNagasaki

SanFrancisco

BONINISLANDS Kagoshima

Sakhalin Paramushiro

MARIANAS

DEPARTED 1830 28 MAY

DATELINE DATELINE

W AE K ORF NT 2400 2 UJ NE

160° 180° 160° 140° 140° 130° 135° 145° 150° 155° 165° 170° 175° 175° 170° 165° 155° 150° 145° 135° 130° 125°

160°E 180° 160°W 140°W 140°E 130°E 135°E 145°E 150°E 155°E 165°E 170°E 175°E 175°W 170°W 165°W 155°W 150°W 145°W 135°W 130°W 125°W

60°N40°N20°N45°N50°N55°N35°N25°N30°N15°N10°N

 5°N

60°40°20°45°50°55°25°30°15°10°

 5°

= U.S. Forces= Japanese Forces

LEGEND

KISKA OCCUPATION FORCE

SECOND MOBILE FORCE

DEPARTED 1200 26 MAY

INTENDED STATION OFGUARD FORCE

1300

3 JUNE

FROM SAN DIEGO

1515

1 JUNE

TF11 (SARATOGA)

1530

0700

3 JUNE

3 JUNE

TF-1 (BATTLESHIPS)

2 CLs 

2 DDs

0500 3 JUNETG 8.6 FORMED

2 CAs2 DDs

1000 29 MAY

RENDEZVOUS

TF 16 & TF 17

1600 2 JUNE

FUELING

31 MAY

TF 17

TF16

0600

30 MAY

MINESWEEPING GROUP

MIDWAY OCCUPATION FORCE

DEPARTED

26 MAY

DEPARTED

26 MAY

MAIN FORCE

FIRST MOBILE FORCE

1500

3 JUNE

1330

3 JUNE

MAP 4: DEPLOYMENT OF THE OPPOSING FORCES

• TRANSPORT GROUP• SEAPLANE TENDER GROUP• CLOSE SUPPORT GROUP 2040 27 MAY

MIDWAY OCCUPATION FORCE

MAIN BODY DEPARTED 28 MAY

DEPARTED 1700 25 MAY

DEPARTED 1300 2 JUNE

ADAK—ATTU OCCUPATION FORCE

DEPARTED EARLY AFTERNOON ON 28 MAY

DEPARTED 30 MAY

DEPARTED 28 MAY

NORTHERN AREA FORCE, MAIN BODY DEPARTED 2 JUNE

0

50

100

150

200

250nm

Map 8

Deployment of the opposing 

forces
J

northeasterly courses to a point some four hundred miles south of Dutch Harbor.255

The Kiska Occupation Force departed Ōminato in the early evening on the 28th, 

stopped at Paramushiro for supplies, then left for Kiska in the early afternoon of 

2 June. The Adak-Attu Occupation Force sortied from Ōminato in the early afternoon of 28 May.256

Both the Midway and the Aleutians forces steamed eastward under the cover of 

carrier aircraft and also shore-based aircraft, from the home islands, Paramushiro, 

Marcus, Wake, and Wotje, as well as from other bases in the Mandates.257

On the American side, TF 16 sortied from Pearl Harbor on 28 May and proceeded to its assigned area northeast of Midway. TF 17 departed Pearl Harbor on 

30 May and advanced to its assigned position northeast of the island. Both TF 16 

and TF 17 were covered by the land-based aircraft from Oahu for the first two days. 

TFs 16 and 17, though not organized as a single force, generally stayed within supporting and visual-signaling distance.258 The reasons for this separation, as noted 

above, were that the carrier forces had different cruising instructions and had never 

operated before together. Another reason, however, was a belief at that time (not 

necessarily correct) that independent carrier groups had a better chance of repulsing an air attack. In addition, there would be a much smaller risk of collision than 

with a large number of ships in a tight formation.259

CTF 7 deployed thirteen submarines to points on 200- and 150-mile-radius circles covering the western and northern approaches to Midway. A few submarines 

were posted on an eight-hundred-mile circle northwest of Oahu; the last ones to 

become available went to a hundred-mile circle also centered on Oahu.260

On 30 May, Nimitz radioed to task force commanders his latest and most detailed information on the composition of the enemy forces. He wrote that the enemy Carrier Striking Force consisted of four carriers and that its screen consisted 

of only two battleships, two heavy cruisers, and a dozen destroyers. The Midway 

Occupation Force had two or three heavy cruisers, two seaplane carriers, from two 

to four seaplane tenders, and from twelve to eighteen transports and cargo ships. 

Nimitz also described a “Close Covering Force” of one carrier or converted carrier, two fast battleships, five heavy cruisers, and ten destroyers. He estimated that 

sixteen enemy submarines were assigned to scout the Hawaii–Midway area. (His 

enemy’s order of battle missed Yamamoto’s Main Force completely.) Nimitz reiterated his belief that the landing on Midway would take place on 5 June (or a day 

earlier than actually envisaged in the enemy plan). He also estimated that carrier air 

attacks could begin on the night of 2–3 June. A radio intercept had revealed that the 

rendezvous point of the enemy forces would be about 685 miles west of Midway, at 

the extreme radius of B-17s.261

Nimitz made a decision on the basis of his estimate of the situation prior to the 

beginning of the operation that the best position for the Striking Force was the 
J

northeast of Midway. That, as noted above, would place the U.S. carriers in a flanking position with respect to the enemy carrier forces, expected to advance from the 

northwest. Spruance was in complete agreement with Nimitz. TF 16 refueled on 31 

May from two fleet oilers, Cimarron and Platte. Spruance took station some 325 

miles northeast of Midway. Fletcher’s TF 17 was refueled by the same two fleet oilers on 1 June and the next day at about 1600 joined TF 16. Fletcher then assumed 

command of both task forces and directed Spruance to operate TF 16 some ten 

miles southward of TF 17 but to remain within visual-signaling range.262

On 31 May, Task Unit (TU) 1.1.4 (Battleships, Battle Force) executed Operation Plan 1-42. The objective was to destroy any enemy surface force about to 

raid the West Coast—the assumption being that the Japanese planned to attack San 

Francisco. TU 1.1.4 sortied from San Francisco—two battleships (Maryland and 

Colorado) and three destroyers—and took a position 650 miles west of San Francisco. 

Task Force 1 lacked organic air cover except for the planes on board the battleships. 

Its position was within the range of the U.S. land-based search aircraft in the San 

Francisco area but outside that of bombers and fighter aircraft. TU 1.1.4 was directed 

to remain until 14 June and then to return to port. The task force’s remaining ships 

would stay at San Francisco to defend its harbor against enemy air attack.263 Task 

Force 11, with the carrier Saratoga, under Rear Admiral Fitch, sailed from San 

Diego on 1 June. However, it would be unable to take part in the defense of Midway 

unless the enemy attack was behind schedule.264

The Midway Phase

Yamamoto’s plan started to unravel almost at the outset. Because of the delays in 

overhaul, the boats of SubRon 5 deployed late. They reached their assigned positions on the Cordon B line on 4 June, two days later than originally envisaged.265

By then the enemy carriers had already passed it. To make the situation worse, the 

planned K operation, intended to provide information on the presence of the enemy fleet at Pearl Harbor, was also derailed. On 31/30 May, a refueling submarine 

reached French Frigate Shoals and to its surprise found two U.S. ships at anchor. 

The 24th Air Flotilla commander accordingly ordered postponement for twentyfour hours, hoping that the enemy ships would depart. This proved to be wishful 

thinking; instead, the Americans deployed seaplanes to the base as well.266 On 30/29 

May, a Japanese submarine reported that enemy activity in the vicinity of French 

Frigate Shoals was extensive and that flying boats were operating there. The same 

evening the commander of the 24th Air Flotilla canceled the entire operation.267 

The First Mobile Force refueled on 31 May and 1 June.268 On 2 June, cloudy 

weather with occasional rain prevailed near Yamamoto’s Main Force. Nagumo’s 

force, some six hundred miles ahead of Yamamoto’s, entered an area of thick fog; 

refueling had to discontinue because of poor visibility.269 Dense fog made it very 

difficult to change the direction of forces’ movement. One of the Japanese supply 
J

ships violated strict radio silence and used a short-range radio to send a message 

to Yamamoto’s flagship, Yamato, then five to six hundred miles away. The Japanese 

assessed that this message was probably heard by the enemy.270 Japanese radio intelligence also reported that of 180 intercepted enemy messages some seventy-two 

were marked “urgent.”271

Movements on 3 June

On 3 June, the First Mobile Force and the Main Force bore 310° from Midway at 

distances of some six hundred and nine hundred miles, respectively. The Transport Group was west, at 650 miles, from Midway; the Seaplane Group was in company with the Transport Group. The Close Support Group was west and 575 miles 

from Midway. The main body was west and 670 miles from the island, and the 

Minesweeping Group, west-southwest 450 miles.272 During the night of 2–3 June, 

Fletcher shifted the Striking Force to an operating area some 175 miles westward of 

code-named Point Luck, 260 miles north of Midway.273

At 0904 on 3 June, Navy PBY search aircraft from Midway made first contact 

with the enemy forces west of Midway, some seven hundred miles away. The sighting report read, “Two cargo ships, bearing 247 and 470 miles from Midway.” At 

0925, another PBY reported, “Main Body, six ships, bearing 261 degrees, and seven 

hundred miles from Midway, course 90 degrees, speed ten knots.”274 A third report, 

received at 1100, cited the presence of eleven ships on an easterly course at nineteen 

knots.275 The first two reports referred in fact to the Minesweeping Group, the third 

to the Transport Group.276

At 1523, nine B-17s from Midway attacked what they reported as five enemy 

battleships or heavy cruisers and forty other ships some 570 miles from Midway. 

They claimed to have hit two ships—one heavy cruiser or battleship and a transport

—and possibly to have damaged another heavy cruiser and a transport.277 However, 

no hits were scored by the B-17s.

On the Eve of the Carrier Engagement

In the night of 3–4 June the First Mobile Force approached Midway from the 

northwest under the cover of a moving front system of scattered showers and a low, 

broken cloud ceiling that varied between a thousand and 2,300 feet. At the leading 

edge of the front was an area of overcast—towering cumulus clouds, heavy showers, and reduced visibility—that prevented effective scouting by American aircraft 

operating from Midway. Farther to the east, the U.S. carriers were under a “dying” 

warm front. The sky was cloudy with high broken and lower scattered clouds; ceilings were unlimited over the task force but dropped to a thousand feet to the west.278

Nagumo’s estimate of the situation prior to the carrier engagement on the 

morning of 4 June illustrates the attitude prevalent among the Japanese commanders regarding the ability of their American counterparts to frustrate and ultimately 
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defeat their plans. Nagumo stated that the “enemy lacks the will to fight” but was 

likely to counterattack if the Japanese landing on Midway proceeded “satisfactorily.” The enemy would conduct reconnaissance mainly to the west and south but 

would not maintain a “strict vigil” to the northwest or north. The radius of the 

enemy patrol aircraft, Nagumo asserted, was about five hundred miles. Nagumo 

was confident that the enemy was not aware of the Japanese plans and assumed 

that his force would not be discovered until the morning of 5 June at the earliest. 

Nagumo also believed that there were no powerful enemy units, with carriers, in 

the vicinity. He was convinced that after attacking Midway and destroying the 

enemy shore-based air strength to facilitate the landing, “we would . . . be able to 

destroy any enemy task force which may choose to counter attack.” In his view, an 

enemy counterattack by shore-based aircraft could be neutralized by defending 

aircraft and AA fire.279

On the eve of the carrier engagement Nimitz sent the following message to his 

subordinate commanders: “The situation is developing as expected. Carriers, our 

most important objective, should soon be located. Tomorrow may be the day you 

can give them the works. The whole course of the war in the Pacific may hinge on 

the developments of the next two or three days.”280

Spruance’s plan was based on a discussion he had had with Nimitz and Fletcher on 27 May. He intended to position his two carriers on the flank of the enemy 

carrier force and to rely on surprise and secrecy. Spruance also wanted to launch 

an all-out attack on the enemy carriers before they attacked his task force, committing his entire air strength in a massive strike and holding nothing in reserve. 

His aircraft would focus their attacks on the enemy carriers. Only if he had aircraft left would Spruance then attack battleships and cruisers.281 Spruance decided not to move westward to close the enemy carriers before they were damaged. 

Spruance also did not want to put TF 16 within seven hundred miles of Wake 

Island, where, he knew, the Japanese had reinforced their air strength. Neither 

did Spruance wish to sail so far west of Midway that the enemy could close in 

with his superior strength and crush him.282

Spruance imposed strict operations-security measures on TF 16. He prohibited any radio transmission that could reveal the positions of ships. No “talk between ships” (line-of-sight radio) could be used, even to bring in an aircraft that 

had failed to return to the carriers.283

The Clash of Carriers

On the morning of 4 June, surface winds in the vicinity of the front northwest of 

Midway were variable. Nearer to Midway the surface winds, under the influence 

of the northwestern high-pressure area, were from the southeast. This was advantageous to the Japanese; their carriers would be closing to Midway when steaming into the wind to launch aircraft. At the same time, the U.S. carriers were at a 
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disadvantage because they would have to turn away from the enemy to launch or 

recover aircraft, wasting time and fuel.284

At about 0430 on 4 June, the First Mobile Force was some 240 miles west of 

Midway. The weather then was clear, with scattered clouds. Visibility was excellent, the ceiling was 1,500–3,000 feet, and the wind was from the southeast. 

Nagumo’s carriers mounted their first strikes, intended to eliminate U.S. air strength 

and soften up ground defenses on Midway. The first wave consisted of 108 aircraft 

(thirty-six fighters, thirty-six bombers, and thirty-six torpedo bombers). The torpedo bombers were armed with bombs, not torpedoes.285 The other half of Nagumo’s 

aircraft were armed with both torpedoes and bombs, in case of an encounter with the 

enemy surface forces. He ordered searches by only eight aircraft (one aircraft each 

from Akagi and Kaga, four Type 0 reconnaissance seaplanes from the heavy cruisers Tone and Chikuma, and two short-range Type 95 seaplanes from the battleship 

Haruna) to cover nearly the entire eastern semicircle out to three hundred miles and 

the northernmost sector out to 150 miles.286 (This number was clearly insufficient.) 

Nagumo also decided not to launch fighters for combat air patrol (CAP). This was in 

contrast to the then-standard American practice of having CAP airborne at dawn.287

At dawn on 4 June, Fletcher moved TF 17 and TF 16 at 13.5 knots to a position 

about two hundred miles north of Midway. Fletcher depended on the Midway aircraft to detect the enemy carriers.288 At 0415, some twenty-two PBYs from Midway 

were aloft, sweeping the western sectors (200°–020°) for the suspected two enemy 

carrier groups. They were directed to search out to seven hundred miles in their individual sectors or until all enemy carriers were found. In case of emergency, PBYs 

would divert to Laysan and Lisianski Atolls.289

At 0545, a PBY reported many enemy planes heading for Midway, 150 miles distant and bearing 320°. At 0552, another PBY sighted two enemy carriers and many 

ships on the same bearing at 180 miles, course 135°, speed twenty-five knots.290 At 

about 0603, Spruance received, in plain language from a PBY based on Midway, a 

first report of the presence of two enemy carriers some 175 miles west-northwest 

from TF 16. (The reported position of the enemy carriers was about forty miles in 

error;291 the actual distance was about 215 miles.) Spruance ordered, “Launch the 

attack.” His order to attack was a calculated risk. A strike at longer distance risked 

the loss of many planes and pilots. His TBD torpedo bombers and the new F4F 

Wildcat fighters had a combat radius of only 175 miles. In contrast, the maximum 

effective range of the SBD dive-bombers was two hundred miles. Spruance knew 

that the enemy had in all four to five carriers. He expected that other enemy carriers 

would be near those already sighted.292 However, this was by no means certain. If 

the enemy carriers were widely separated then Spruance risked using all his aircraft 

against only a part of the enemy force and thereby exposing his TF 16 to attack by 

other enemy carriers.293
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At 0620, TF 16 and TF 17 were directed by Fletcher to operate five to ten miles 

apart. After receiving a contact report by the Midway plane on the enemy forces

—described as composed of two carriers and other ships, including battleships, 

bearing 320°, 180 miles from Midway, course 135°, speed twenty-five knots—

Fletcher directed Spruance to proceed westward and launch attacks.294 TF 16 then 

steamed on a westerly course at twenty-five knots. The sea was calm and the visibility good, the wind six to seven knots from the south-southwest.

At 0648 Spruance divided TF 16 into two groups, each centered on a carrier 

(they would operate separately until 1930 on 4 June). At about 0700, Spruance estimated that Nagumo’s force was about 155 miles away (the actual distance was 190 

miles). Enterprise and Hornet started to launch their first attack waves at 0702. Each 

carrier launched sixty aircraft (thirty-five dive-bombers, fifteen torpedo bombers, 

and ten fighters). Within half an hour the launch was completed.295 At 0830, Yorktown started launching only thirty-five aircraft (seventeen dive-bombers, twelve 

torpedo bombers, and six fighters). Fletcher had decided to keep the major part of 

TF 17’s aircraft in reserve pending more reliable information on the enemy carriers 

from the Midway aircraft.296

Spruance knew that his force had been detected by an enemy search plane and 

that he had lost the factor of surprise. Yet he erroneously believed that the seaplane 

that had sighted TF 16 was from a tender located southeast of Midway (it was actually from the cruiser Tone).297 Browning calculated that the Japanese planes attacking Midway could not return to their carriers until 0900, until which time the 

enemy commander, even if he knew where the U.S. carriers were, had to maintain 

course toward Midway to recover them. However, the Japanese recovered their 

planes earlier than Browning anticipated.298 Spruance intended to hit the two reported enemy carriers before they carried out a second strike on Midway.299 The 

presence of the third enemy carrier was not known to Spruance at that time, and 

that of the fourth until much later.300

At about 0700, Nagumo received a report from the leader of the first wave that 

a second attack on Midway would be necessary. Believing that there was no threat 

from enemy forces, Nagumo decided on a second strike.301 He discontinued the 

standby status of the ninety-three planes he had been keeping in reserve and ordered (in what proved to be a fatal mistake) that aircraft be dropped to the hangar 

decks to clear the flight decks for recovery of the Midway strike. Nagumo ordered 

the torpedo planes on Akagi and Kaga to be rearmed with bombs and the divebombers in Hiryū and Sōryū to carry high-explosive instead of armor-piercing 

bombs. The rearming of the aircraft would require about one hour in all.

Between 0700 and 0830, some sixty aircraft based on Midway made repeated 

attacks on the enemy carriers. All encountered fierce resistance by Japanese fighters 
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and heavy AA fire from the ships. At about 0600, CNAS Midway directed fourteen 

Army B-17s then en route to attack the Midway Occupation Force to attack instead 

the enemy carriers, then some two hundred miles northeast of their own position. 

At 0710, four Army B-26s armed with torpedoes attacked the enemy carriers from 

an altitude of two hundred feet but scored no hits; two of the B-26s were shot down, 

and the surviving two were heavily damaged and made unfit for further use.302 At 

0755, sixteen Marine dive-bombers conducted a “gliding” attack (that is, rather 

than from a nearly vertical dive, because of the inexperience of the pilots); eight 

were shot down, and the other eight returned to base damaged (two of them so 

badly as to be written off).303 At 0810, the third attack, by the fourteen B-17s, immediately followed; 8,500 pounds of bombs were dropped from altitudes of twenty 

to twenty-three thousand feet. The B-17s claimed three hits and two probable hits 

on the enemy carriers, but all their “hits” were actually near misses.304 At about 0820 

(or 0827), eleven Marine dive-bombers from Midway flew over the carriers but 

attacked the battleship Haruna instead, making no hits. At almost the same time 

six torpedo planes from Midway attacked Nagumo’s carriers; their attack failed, 

though all but two planes returned safely.305

Nagumo first received reports of the presence of the enemy force at 0728 from 

the No. 4 search aircraft launched by Tone. The message he received stated, “Ten 

ships, apparently enemy, sighted, bearing 010 degrees, distant 240 miles from Midway, course 150, speed more than 20 knots.” This critical message reached Nagumo 

after several minutes’ delay. It came as a surprise to Nagumo and his staff, who had 

not anticipated an enemy force would appear so soon. The lack of precise information on the composition of the enemy force led Nagumo to send a reply, “Ascertain 

ship types and maintain contact.”306 The pilot replied at 0809, “Enemy is composed 

of five cruisers and five destroyers.” One minute later, an amplification was added 

that the enemy was accompanied by “what appears to be a carrier.”307 By 0800, the 

wind had weakened to a light breeze, four or five knots. This forced Nagumo’s carriers, to generate sufficient wind over their flight decks, to steam at twenty-one 

knots away from the enemy’s carriers in order to launch and recover. Visibility was 

thirty-five to forty miles, and the temperature was pleasantly cool (68–70 degrees 

Fahrenheit).308

By 0745, Nagumo had changed his mind about the second strike on Midway. 

He directed his force, “Prepare to carry out attack on enemy fleet units. Leave torpedoes on those attack planes which have not as yet changed to bombs.” At that 

time, Akagi and Kaga were already thirty minutes into rearming their torpedo 

planes with 1,765-pound bombs; the process was more than half complete. Hence, 

Nagumo ordered that the rearming of the two other carriers’ torpedo planes be immediately suspended and directed his whole force to prepare for a possible attack 
J

on enemy ships. In addition, all the Zeros he had assigned as the escort for the second strike on Midway were sent aloft to reinforce the CAP that had been launched 

against the repeated attacks by U.S. land-based aircraft. As a result, the only aircraft 

armed appropriately for an attack on ships and on the flight decks ready for takeoff 

were thirty-six dive-bombers of Hiryū and Sōryū. Nagumo believed that the risks 

of sending out an attack force without fighter protection were too great. Hence, he 

thought that the wiser course was first to recover both the Midway strike planes 

and the second-wave fighters that had been diverted to CAP and then, temporarily retiring northward to avoid further air attack, to reorganize his forces. Finally, 

when all preparations were complete, Nagumo planned to turn around and destroy 

the enemy carrier force by an all-out attack.309 Admiral Yamaguchi of CarDiv 2 advised Nagumo to launch instead an immediate attack with aircraft until then held 

in reserve against the detected enemy carrier to the northeast. Nagumo ignored 

that advice and made a fateful decision to delay his attack until he was ready for a 

massive and coordinated strike.310

Yamaguchi had extensive sea service. Prior to 1941 he had commanded in turn 

a light cruiser, heavy cruiser, and battleship, and the IJN’s first combined air group. 

He was known as a highly aggressive and competent but also hot-tempered officer

—the epitome of the traditional samurai code. Yamaguchi had had misgivings 

about Nagumo’s ability to command the First Air Fleet. He had even gone so far as 

to complain to Ugaki that Nagumo lacked boldness.311

At 0845, Nagumo sent a message to Yamamoto and Kondō, “Enemy force of one 

carrier, five cruisers and five destroyers discovered at 0800, bearing 010 degrees, 

distant 240 miles from Midway; we will head for it.” Nagumo expected to have 102 

aircraft ready for launching at 1030. Most of the fighters would have to be used to 

defend their own carriers; only twelve Zeros would be assigned to protect the attacking dive-bombers.312 Yet his planned attack group had already broken down, 

because he had to recover the aircraft returning from their attack on Midway. To do 

that, Nagumo’s four carriers were grouped in a boxlike formation in the center of a 

screen of two battleships, three cruisers, and eleven destroyers.313

The attack by the U.S. aircraft was piecemeal (see map 9). The three air groups 

searched for the enemy independently. The fighter aircraft failed to protect slow 

torpedo planes from the enemy CAP. Hornet’s dive-bombers never found the enemy carriers.314 The lack of fighter cover, the poor visibility, the distance, the delay 

in locating the enemy force, and the Japanese tactics of concentrating their fighters against slow torpedo bombers combined to prevent a coordinated attack by 

the Enterprise and Hornet air groups. Moreover, it resulted in heavy losses for the 

torpedo bombers.315 At 0920, Hornet’s torpedo bombers attacked without waiting 

for the arrival and support of dive-bombers. About eight miles from the carriers 

they were intercepted by the enemy fighters and were shot down one by one. Not a 

single torpedo bomber survived.316 Around 1000, torpedo bombers from Enterprise 
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Map 9

The Midway phase, 0900–

2400, 4 June 1942

1300

MAIN GROUP500 MILESBEARING 296° FROM FIRST MOBILE FORCEAT 1300

1150 YORKTOWN LAUNCHES 10 VSB

SEARCH AND ATTACK

200 MILES

1133

1150

TF 17

0900

0902 YORKTOWN LAUNCHES

17 VB, 12 VT, 6 VF.

TF 16

0900

1205-15 HIRYU PLANES DIVE BOMB YORKTOWN

3 HITS. 1300

CTF 17 SHIFTS FLAG TO ASTORIA

1000 1100

1209 1300

EXPECTED POSITION OFINTERCEPTION BY TF 16AIR GROUPS

0920

HORNET VSB & 8 VFTURNS SOUTH

0955 0900

HORNET VT ATTACK 0928ENTERPRISE VF OVERHEAD

ENTERPRISE VSBSIGHTS 1 SHIP ONCOURSE NE

FIRST

MOBILE FORCE

0900

1022—1028 ENTERPRISE VSB ATTACK

NAGUMO

SHIFTS FLAG TO NAGARA

1100

 1045 1200

HIRYU LAUNCHES

18 VB, 6 VF.

Dive bomb hits

1022 Kaga 4 hits1025 Akagi 3 hits1028 Soryu 3 hits

TF 17

TF 16

2400

4

2400

4

ENTERPRISE LAUNCHES 2ND ATTACK 1530—1550-24-VSBHORNET LAUNCHES 16-VSB 1603—1614

1915

2400

4

1400

1331

1705 HIRYU DIVE BOMBS

4 HITS

TONE PLANE #2

070° -150 MILES

090° -150MILES TONE PLANE #1

CHIKUMA 4 PLANE #3 050° - 150 MILES

HIRYU LAUNCHES

10 VT, 6 VT.

MAIN BODY390 MILES, 272° FROM MIDWAYAT 1300

KURE

TRANSPORT GROUP375 MILES, 260° FROM MIDWAYAT 1300

MIDWAY

VB

VF

VSB

VT

= DIVE BOMBER= FIGHTER= SCOUTING BOMBER= TORPEDO BOMBER

LEGEND

MAP 5: THE MIDWAY PHASE 0900—2400, 4 JUNE 1942

(TIME ZONE + 12)

180° 179° 178° 177° 176° 175° 32°

31°30°29°
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and Yorktown attacked the enemy carriers, and they too met heavy opposition. Enterprise lost ten out of fourteen torpedo bombers and Yorktown ten out of twelve. 

Yet, by accident, coordination of torpedo and dive-bomber attacks was almost 

achieved—the dive-bombers struck only a few minutes after the attack of the torpedo bombers had ended.317 Of forty-one torpedo planes from three American carriers, all but six were lost. Nevertheless, the attacks by the torpedo bombers forced 

the enemy carriers to make radical evasion maneuvers, which in turn prevented 

them from launching more aircraft. Also, the torpedo bombers pulled Japanese 

fighters down to near sea level, enabling the dive-bombers that followed a few minutes later to attack virtually unopposed and to drop bombs on decks full of aircraft 

being refueled.318

At 1020, Nagumo ordered the launch of an attack group of thirty-six divebombers (eighteen from Hiryū, eighteen from Sōryū), fifty-four torpedo bombers 

(eighteen each from Akagi and Kaga, nine each from Hiryū and Sōryū), and twelve 

fighters (three from each carrier). Yet just two minutes later, two dive-bomber 

squadrons from Enterprise and one dive-bomber squadron from Yorktown appeared overhead. Within five or six minutes, three Japanese carriers were heavily 

damaged and left burning; Kaga received four bomb hits and five near misses; Sōryū

and Akagi suffered three hits each.319 At 1046, Nagumo left Akagi and transferred 

his flag first to a destroyer (Nowaki) and then to a cruiser (Nagara). Five minutes 

later he sent a message to Yamamoto, “We plan to have Hiryū engage enemy carriers; we are temporarily withdrawing to the north to assemble our forces.”320

By 1100 Admiral Yamaguchi had launched eighteen dive-bombers and eight 

fighters from Hiryū. They reached Yorktown at about noon and scored three bomb 

hits.321 Yorktown was heavily damaged and listing; soon the ship was dead in the 

water. At 1313, Fletcher shifted his flag to the cruiser Astoria. Spruance, observing 

the big, black cloud, assumed that Yorktown had been hit hard and dispatched two 

cruisers and two destroyers to help and provided fighter protection for the crippled 

carrier.322 Yorktown’s planes landed on Enterprise and Hornet and took part in all 

subsequent attacks.323

In the meantime, at about noon, Kondō, acting on his own initiative, notified 

Yamamoto that his force was heading toward the First Mobile Force at twenty-eight 

knots. Some twenty minutes later, Yamamoto issued the following order: “All forces 

will operate as follows and attack the enemy in the Midway area; 1200 position of 

Main Body 35° 08ʹ N 171° 05ʹ W; course 120 degrees, speed 20 knots.” He directed 

Kondō to rendezvous with the First Mobile Force as soon as possible. The Midway 

Occupation Force was to detach part of its strength to cover the Transport Group 

and withdraw temporarily to the northwest. SubRons 3 and 5 were ordered to take 

positions along the Cordon C line.324 Yamamoto realized that though at that time he 

had two carriers left, only one was available for combat, Hiryū. That is the reason 
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that he directed Second Mobile Force to join Kondō’s main body. He also temporarily postponed the landing on Midway and Kiska.325

At about 1310, Yamamoto directed Kondō’s main body to conduct a night bombardment of Midway. This task was assigned to Rear Adm. Takeo Kurita’s Close Support Group. Kurita received that order at about 1500. He was at that time some four 

hundred miles west of Midway and his chances of reaching the target area before 

dawn were slim. In any case, he would have to withdraw during the daylight and 

would be vulnerable to the enemy’s air attack.326

Yamamoto also started to prepare his remaining forces for a night action. In 

Order No. 156, issued around 0950, he specified “Method C” a pre-scripted tactic 

stipulating engagement by the entire fleet, according to doctrine, with major elements of the enemy force moving westward. The Second Mobile Force would come 

under command of the main body, Second Fleet. SubRons 1, 3, and 5 would be under the Advance Expeditionary Force (Submarines) commander. The Main Force 

operating in the Aleutians area would be joined by, presumably, the Guard Force.327

Spruance intended to destroy the remaining enemy carrier, Hiryū, but wanted to 

delay the attack until he learned its exact position.328 An element in the decision was 

that Enterprise and Hornet needed more time to get themselves organized and their 

planes rearmed and refueled.329 Browning contested Spruance’s decision and urged 

an immediate launch. Yet Spruance was adamant. For some reason, Spruance did 

not launch any search planes, either from the carriers or from cruisers. Spruance 

was content that someone else should find the enemy.330

By 1402 Yorktown had its flight deck operational and was able to steam at nineteen knots. However, ten torpedo bombers from Hiryū attacked Yorktown at 1445 

and scored two torpedo hits, causing complete loss of power. Within twenty minutes after being hit, the crew began to abandon the ship. However, Yorktown continued to float despite a heavy list.331

At 1445 a Yorktown plane reported a Japanese force of one carrier plus other 

heavy ships and destroyers some 110 miles west of the U.S. forces. Spruance now 

finally gave the order to launch a second attack. However, Browning and staff carried out the order poorly, although they had had plenty of time to prepare. The second attack was launched not until 1515, or fully thirty minutes after the order was 

given. Someone on Spruance’s staff signaled Hornet that Spruance did not know 

the position of the enemy carrier whose planes were attacking Yorktown. Three 

minutes later Spruance’s staff sent Hornet a corrected message relaying the contact 

information received on board Enterprise a half-hour earlier. Still Hornet did not 

receive an order to attack, although Spruance had given the order to Browning thirty minutes earlier. At 1530 Enterprise started to launch twenty-four dive-bombers, 

many of them survivors from Yorktown. Finally the staff sent a signal to Hornet at 

1539 to launch its attack group, less the fighters. Hornet started launching its planes 
J

at 1605; sixteen dive-bombers were launched, while the fighters remained behind 

to protect the carriers. For the second time Browning and the staff failed to support 

properly Spruance at the most critical times. Obviously, the earlier raids by TF 16 

against weakly defended strongpoints in the Central Pacific had not prepared them 

for the much more demanding work of a carrier-versus-carrier engagement.332

Now it was Hiryū’s turn to be attacked, by dive-bombers from TF 16’s carriers. 

At about 1700 Enterprise’s dive-bombers scored four, possibly five, bomb hits on 

Hiryū; Hornet’s planes scored no hits. By 1800, Hiryū was left ablaze and unable to 

operate aircraft. Kaga, abandoned at about 1640, exploded and sank at 1925; Sōryū

sank at 1913; and two minutes later, Akagi was abandoned. 

Despite the horrendous losses of the day, Yamamoto sent a message at 1915 that 

read as follows: “The enemy fleet has been practically destroyed and is retiring eastward; Combined Fleet units in the vicinity are preparing to pursue the remnants 

of the enemy forces and, at the same time, to occupy Midway; the main body will 

reach 32° 08ʹ N 175° 45ʹ E at 0300 on 5 June; course 090°, speed twenty knots; the 

First Mobile Force, the Midway Occupation Force less CruDiv 7 and submarine 

force will immediately contact and attack enemy.”333 At 2340 Kondō issued an order 

for a night action: “The Midway Occupation Force, the main body will reach position 30° 28ʹ N 178° 35ʹ W at 0300 on 5 June. Afterward, the searches will be conducted eastward in an effort to engage the enemy at night. The First Mobile Force 

less Hiryū, Akagi, and their escorts will reverse course immediately and participate 

in the night engagement.”334

The Night of 4–5 June. At about 1845, Fletcher detached two cruisers, Vincennes 

and Pensacola, to join Spruance’s TF 16. He delegated responsibility for combat to 

Spruance; Fletcher would take charge of efforts to salvage Yorktown the next morning.335 But that evening Spruance lost contact with the enemy forces. Yorktown was 

nonoperational. TF 16’s carrier air groups had been decimated. No support from 

other forces was in sight. Spruance had to weigh the risks of pursuit versus possible 

damage to the enemy. In his report he wrote, “I did not feel justified in risking a 

night encounter with possibly superior enemy forces but on the other hand I did 

not want to be too far away from Midway the next morning. I wished to have a 

position from which either to follow up retreating enemy forces or to break up a 

landing attack on Midway.”336 Accordingly, at 1915 Spruance set TF 16 on a course 

to the east at a speed of fifteen knots.337

Spruance later said of his decision not to pursue the enemy force during the 

night of 4–5 June, “We had to keep moving because of the possible presence of enemy submarines. Our primary mission was still to prevent the capture of Midway. 

We did not know whether the enemy would continue with that task, or whether 

the loss of his three carriers, and the damage we had inflicted on the fourth, would 
J

cause him to give up the attempt. Should I continue steaming west, with a view to 

overtaking and engaging the enemy? If I did this, we would run the risk of a gun 

engagement during the night with possible superior forces, at a time when our two 

aircraft carriers could not operate. . . . The Japanese were believed to have two fast 

battleships with their carrier force. The Japanese were reputed to be well trained in 

night gunnery and in night destroyer attacks.”338 Spruance turned back westward 

shortly after midnight on 5/4 June. 

Spruance was criticized for abandoning the pursuit. Yet he made a sound decision, because the Japanese had in fact started to concentrate their forces, leaving the 

transports almost unprotected. At 1400 on 4 June, Kondō’s force of four heavy cruisers, two Kongō-class battleships, the light carrier Zuihō, and one destroyer squadron changed course to the northeastward. By midnight Kondō was some 125 miles 

from Nagumo’s battleships and cruisers. Rear Adm. Raizō Tanaka, the commander 

of DesRon 2, with one light cruiser and ten destroyers, was not far behind. Had Enterprise and Hornet sailed westward they would have run into the Japanese ships.339

Yamamoto’s Decision. At 0015 on 5 June, Yamamoto ordered Nagumo and Kondō, 

whose forces were, respectively, maneuvering for a night attack on the enemy carriers and a bombardment of Midway, to suspend these operations and join the 

main body: “The Midway Occupation Force (less the Transport Group presently 

standing by, but including CruDiv 7) and First Mobile Force (less Akagi, Hiryū,

and their escorts) will join the Main Body at 0900 today. The Main Body will be 

in position 32° 08ʹ N 179° 01ʹ E; course 090 degrees speed 20 knots.”340 Yamamoto 

had learned that Kurita’s force’s position had been in error and that he could not 

possibly conduct a bombardment on schedule.341 At 0215, two heavy cruisers from 

Kurita’s Close Support Group, Mogami and Mikuma, collided while maneuvering 

to avoid a submarine contact; both were damaged, Mogami heavily. 

At 0255, Yamamoto sent a message canceling the Midway operation. He directed Kondō’s main body, the Midway Occupation Force, and the First Mobile Force 

(less Hiryū and its escorts) to refuel in the morning of 5 June. The Transport Group 

was directed to sail westward, out of range of aircraft from Midway.342 By the early 

morning, both Akagi and Hiryū had sunk. 

Attacks by Task Force 16 on 5 June. At daybreak on 5 June, TF 16 headed westward 

at fifteen knots and into bad flying weather. When the weather cleared, Spruance 

had a choice between two groups of enemy ships to attack, one west of Midway and 

the other northwest. Spruance chose to attack the one to the northwest, which was 

farther away but reportedly contained a crippled carrier and two battleships, one of 

them reported damaged.343

At 1700, Spruance launched air searches out to 250 miles. His aircraft found two 

groups of the enemy ships to the southwest some forty miles apart. The southerly 
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group consisted of two heavy cruisers and two destroyers. The initial search report 

indicated that the other group consisted of one carrier and five destroyers; this was 

later corrected to one battleship and three destroyers, then to two heavy cruisers, 

one light cruiser, and two destroyers.344 The situation during the night of 5 June was 

not promising for inflicting further damage, so Spruance ordered TF 16 to turn 

westward and steam at fifteen knots for the rest of the night. Spruance ordered this 

slow speed because he did not want to run into enemy battleships; another reason 

was a shortage of fuel in his destroyers.345

The Final Actions. At 0510 on 6 June, TF 16 launched eight dive-bombers for a twohundred-mile search in the western semicircle. They made two contacts: at 0640 

on two heavy cruisers and two destroyers four hundred miles from Midway, and 

at 0645 the heavy cruisers Mikuma and Mogami, 435 miles from Midway. Hornet’s 

planes struck Mogami between 0930 and 1000. At 1140, the Enterprise group disabled Mikuma. About 1500, Hornet launched a final attack that sank Mikuma and 

left Mogami gutted and abandoned.346

In the morning on 6 June, the heavily damaged Yorktown was still afloat; the 

salvage parties were on board, the destroyer Hammann was secured alongside, 

and four other destroyers circled nearby to provide protection against submarines. 

However, a search plane from Chikuma sighted Yorktown and transmitted the information to the submarine I-168. At 1335, Yorktown and Hammann were hit with 

two torpedoes each; both sank, with considerable loss of life.347

In the midafternoon of 6 June, Yamamoto apparently renewed his hopes of 

fighting a decisive battle with the enemy carriers. He estimated that the enemy now 

had at least one carrier, two converted carriers, and several cruisers and destroyers. 

Should the enemy forces continue in pursuit, Kondō would be able to engage them 

in a night battle; alternatively, Yamamoto’s Main Force would be able to fight a decisive battle the morning of 7 June. In Yamamoto’s mind, the key prerequisite for success was to neutralize the enemy’s airpower. However, he was left with only about a 

hundred aircraft on board four light carriers (Hōshō, Zuihō, Ryūjō, and Junyō), aside 

from the seaplanes carried by battleships, cruisers, and seaplane tenders. Therefore, 

it would be necessary to lure the enemy force within the range of the fifty bombers 

on Wake Island. Yamamoto issued an order at 1500 to all ships: “Combined Fleet 

units operating in this area will catch and destroy the enemy task force within attack range of air forces based on Wake Island. At 1530 from position 33° 24ʹ N 169°

00ʹ E, the main body, First Mobile Force, and 2nd Section of BatDiv 3 will proceed 

on course 180 at 18 knots. The Guard Force will support Northern Area Force. The 

Eleventh Air Fleet will take every opportunity to attack the enemy.”348

By sundown on 6 June, TF 16 was some four hundred miles west of Midway. Its 

pilots had seen three full days of action. Spruance had detached destroyers to be refueled, and four of those remaining were low on fuel. This did not provide a margin 
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of safety in an area where enemy submarines were operating. There would be little 

gain in a stern chase, and if he continued westward, there was a good possibility of 

running into superior enemy forces. Spruance ordered a turn to the east.349

The Aftermath. Because the enemy fleet was not detected and his destroyers were 

low on fuel, Yamamoto decided at about 0700 on 7 June to call off the attempt to 

reengage and instead to return to home waters.350 The Midway operation would end 

with the return of the Combined Fleet to its bases on 14 June.

On 8 June, Spruance broke off pursuit and steamed to the refueling rendezvous 

with TF 17. Nimitz ordered TF 16 to receive replacement aircraft for Enterprise and 

Hornet and then proceed northward to join with TF 8 to oppose Japanese forces 

reportedly converging on Dutch Harbor. When that report proved false, Nimitz 

ordered Spruance to return to Pearl Harbor.351

The Aleutians Phase

Just prior to and during (see map 10) the execution of the Aleutians operation, 

much of the information the Japanese received on the situation was obtained from 

aircraft launched by the seaplane tender Kimikawa Maru or submarines of SubRon 

1, which became part of Northern Area Force on 10 May. Three SubRon 1 submarines were directed to the eastern part of the Aleutians to reconnoiter the islands 

of Chirikoff, Sitkinak, and Kodiak.352 These boats left the Kodiak area at the end of 

May and patrolled the waters off Seattle. The remainder of SubRon 1 left Japan in 

mid-May. Four boats were directed to patrol the approaches of, respectively, Dutch 

Harbor, Adak, Attu, and Kiska. After reconnoitering these areas they were to cruise 

along the southern side of the Aleutian chain from a point some three hundred 

nautical miles south of Kiska. By 4 June they had reached a point about two hundred miles south of Dutch Harbor.353 

On the basis of this air and submarine reconnaissance, Admiral Hosogaya believed that Dutch Harbor could be easily captured. He believed (incorrectly) that 

Kiska and Attu had land defenses and patrol craft. Also, from intercepted radio 

messages, Hosogaya estimated that there were about twenty patrol aircraft and ten 

fighters based at Dutch Harbor. (In reality, there were only twelve patrol planes at 

Dutch Harbor, plus four patrol aircraft at Cold Bay and Sand Point. There were 

no fighters at Dutch Harbor, but there were twelve to seventeen at Fort Glenn on 

Unimak Island.) Hosogaya learned from radio intercept that after 5 June five enemy 

surface ships would be dispatched from Hawaii to reinforce the Aleutians. The evidence of more ships at Dutch Harbor was only fragmentary. On 2 June, Hosogaya 

received an assessment from Japanese naval intelligence: “It seems that reinforcement to the extent of sixteen patrol planes [has] been recently made. There are now 

two squadrons each in Kodiak and one at Sitka, operations of patrol aircraft based at 

Dutch Harbor are frequent; it is difficult to determine accurately the radius of these 

operations but it seems some three hundred miles.” The Japanese had a fair estimate 
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PATROL VESSELS 0900 13 0000

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(Fort Randall)

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50°N

170°W 160°W 180°W170°W 160°W 180°W

MAP 6: THE ALEUTIANS PHASE

1700

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HOUR

DAY

= U.S. Forces= Japanese Forces=

LEGEND

Map 10

The Aleutians phase
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of the enemy strength on the Aleutians. However, they had no knowledge of the 

newly constructed Army airfield, or its assigned aircraft, at Fort Glenn on Unimak 

Island. This was to have an adverse effect on the operations of Admiral Hosogaya.354

The weather had a significant effect on the employment of Japanese carrierbased aircraft during the Aleutians operation. On 3 June, a low-pressure area 

was centered some four hundred miles due east of Dutch Harbor. Another low 

was about 150 miles northwest of Attu. There was between them a ridge of high 

pressure. Showers and low ceilings were characteristic of the weather except for

the high-pressure ridge, where flying conditions were average. On 3 June average flying conditions prevailed in the Dutch Harbor area. The next day, however, a low-pressure area was centered northwest of Dutch Harbor; its related frontal system was just west of Dutch Harbor and moving eastward—the 

same that had been in the vicinity of Attu the previous day. Yet another lowpressure area and frontal system was some 360 miles to the west of Dutch Harbor 

and moving also in an easterly direction. Dutch Harbor itself had low ceilings and 

reduced visibility due to fog. By 1530 of the 4th the first front had passed and the 

weather cleared; overcast gave way to scattered clouds at three thousand feet, and 

the visibility improved except for fog in scattered areas.355

On 3 June, the Second Mobile Force made a run toward Dutch Harbor, eluding U.S. search planes. By 0250 on the 4th, the Japanese carriers had reached their 

launching position 165 miles south of Dutch Harbor.356 The first strike was launched 

at about 0430 on 3 June. The attack group was composed of fifteen aircraft (six 

fighters and nine dive-bombers) from Ryūjō and twenty-one aircraft (nine fighters and twelve bombers) from Junyō. The weather at the launch point was very 

unfavorable—poor visibility and low clouds (650 to 980 feet). For that reason, the 

carriers had to attack independently. Because of the bad weather, Junyō’s group had 

to turn back.357 Ryūjō’s group, however, found good weather, with a ten-thousandfoot cloud ceiling, over Dutch Harbor. It struck shortly after 0807. The attack lasted 

about twenty minutes and inflicted considerable damage. A new strike at 0900 was 

ordered against five U.S. destroyers at Makushin Bay, on the northwest side of the 

same island, Unalaska. Second attack wave consisted of nine aircraft (three fighters 

and six dive bombers) from Ryūjō and twelve aircraft (six fighters and divebombers) each from Junyō. However, the weather there favored the defenders, and 

the Japanese aircraft were unable to locate the destroyers.358 The Japanese carriers 

and destroyers, which had approached Dutch Harbor to a distance of 130 miles, at 

around 1200, started their withdrawal. That day TF 8’s main body was some five 

hundred miles southeast of the Second Mobile Force but Theobald was unable to 

locate the enemy force. On 4 June he received word of a strike on Dutch Harbor. 

Theobald then, in the evening on 4 June, left the main body on board cruiser Nashville and headed for Kodiak.359
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In the meantime, on 4 June, the U.S. aircraft on Umnak, at Dutch Harbor, and 

at Cold Bay had lost contact with the Second Mobile Force. They tried to regain 

contact for days but ultimately failed. The enemy carriers were beyond their effective range. The situation in the Aleutians was very confusing and uncertain and 

produced many false reports. Not even Nimitz had full knowledge of the situation 

in the north.360

Rear Adm. Kakuji Kakuta’s Second Mobile Force refueled destroyers during 

the night of 4–5 June and changed course westward for Adak; he had received 

orders from Yamamoto to soften up the enemy defenses on the island. However, 

the fog became so thick that he had to reduce speed to nine knots. Bad weather 

was predicted to the west, but there would be good weather over Dutch Harbor. 

In fact at about 1200 on 5 June a reconnaissance aircraft from Ryūjō reported that 

weather conditions over Dutch Harbor were improving. So Kakuta decided to 

launch a second attack against Dutch Harbor. At 1600 his carriers launched thirtytwo aircraft (eleven dive-bombers, six torpedo bombers, and fifteen fighters). The 

Japanese aircraft destroyed oil tanks, seaplane hangars, and other installations in 

the Dutch Harbor area. American pilots, however, finally detected the enemy carriers. Junyō’s group encountered on its way back some ten U.S. fighters east of 

Umnak Island. The Japanese claimed eight enemy planes shot down, of which 

four would be confirmed; Japanese losses were one fighter and four bombers.361

Several Army heavy bombers sent to attack the carriers scored only several near 

misses.362

The plan for the Aleutians operation underwent several changes after the First 

Mobile Force lost three carriers. At 0920 on 5 June, Yamamoto issued Operation 

Order No. 155, directing the Second Mobile Force to join the First Mobile Force 

in the Midway area. Some thirty minutes later Yamamoto issued his orders for a 

decisive battle using Method C, and temporarily suspended the Aleutians operation. The Second Mobile Force and DesRon 1 headed toward Midway. At 2355 on 

5 June (Tokyo time), Yamamoto canceled the attack on Midway. At 0700 on the 

6th the Second Mobile Force and DesRon 1 were returned to the Northern Area 

Force, by Combined Fleet Order No. 162. The same order directed that the Northern Area Force be reinforced by two battleships (Kirishima and Hiei) of BatDiv 3, 

the two heavy cruisers (Tone and Chikuma) of CruDiv 8, the four destroyers of 

DesDiv 4, one seaplane tender (Kamikawa Maru), and one light carrier (Zuihō).

However, this order was canceled on 8 June.363 The Northern Area Force would instead be reinforced by the other two battleships of BatDiv 3 (Kongō and Haruna),

CruDiv 5 (Myōkō and Haguro), CruDiv 9 (Kitikami, Ōi), and Zuihō, plus, after 13 

June, one large carrier (Zuikaku) from CarDiv 5, the four destroyers from DesDiv 

20, three each from DesDiv 24 and DesDiv 27, and two fleet oilers (San Clemente 

Maru and Toa Maru), accompanied by one destroyer.364
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The Japanese landing forces moved eastward toward their assigned objectives 

in the western Aleutians under the cover of the weather front. Only the most 

fragmentary air reconnaissance was possible.365 In the morning on 5 June, the 

Adak-Attu Occupation Force reached a position about six hundred miles southwest of Adak. Then an order was received from Hosogaya that the Aleutians 

operation had been temporarily suspended and that DesRon 1 was to sail south 

to take part in the Midway operation. However, the next day, at about 1300, an 

order was received from Yamamoto that the Northern Area Force was to resume 

the Aleutians operation according to Alternative Plan No. 5.366 This plan, drawn 

up in case the landing at Adak was canceled, envisaged that the Adak-Attu Occupation Force would invade only Kiska and Attu. The Second Mobile Force 

would be tasked to destroy installations on Adak.367 The Adak-Attu Occupation Force turned back and proceeded to Attu. Some 1,200 Japanese troops were 

landed at Holtz Bay during the morning of 7 June. However, because of the 

dense fog, a part of the landing force struck Massacre Bay instead, capturing 

the entire population of some forty Aleuts, including fifteen children, and two 

Americans. 

The Kiska Occupation Force, augmented by one seaplane tender and one destroyer from the Adak-Attu Occupation Force, proceeded according to the plan 

and landed on Kiska on 7 June. There was no opposition; only ten members of 

the U.S. weather station were on the island.368

Upon the news of the Japanese landings on Attu and Kiska, a U.S. seaplane 

tender with PBYs headed toward Atka Island (in the Andreanof group), halfway 

between Dutch Harbor and Kiska. On 10 June, the PBYs discovered four enemy 

ships in Kiska Harbor and a tent colony on Attu. This was the first indication for 

the American commanders of the Japanese presence in the western Aleutians. 

After receiving these reports, Nimitz promptly ordered a submarine group to 

move toward the western Aleutians. He also directed the PBYs with the seaplane 

tender then at Nazan Bay, on Atka, and Army bombers at Cold Bay to bomb 

enemy positions. These attacks were conducted over two days but had no effect 

on the Japanese. On 14 June, the Japanese moved their flying boats from Paramushiro to Kiska and then attacked the U.S. positions at Nazan Bay.369

In the aftermath of the battle of Midway, Nimitz intended to send the carriers 

Enterprise and Hornet to rendezvous with Saratoga, take on replacement planes, 

and proceed north to engage the Japanese. Theobald came ashore at Kodiak on 

8 June to confer with his commanders on how to destroy the Japanese force. 

Returning to his flagship, he sailed south of Kodiak. On 10 June he learned that 

Enterprise and Hornet would not come north and that the enemy had already occupied Kiska and Attu. Theobald again went ashore on Kodiak so that he could 

be better informed on the situation and make necessary decisions.370
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The Japanese occupation of Attu and Kiska did not remain uncontested by the 

Allies. The U.S. surface forces, submarines, and Army aircraft were involved in a 

series of skirmishes with the enemy forces in the summer of 1942 and in the winter/

spring of 1943. In August 1942, the Army established an air base on Adak Island. 

The largest action was the battle of the Komandorski Islands on 26 March 1943. 

Then, a cruiser/destroyer force (one heavy and one light cruiser and four destroyers) under Rear Adm. Charles McMorris tried to destroy a Japanese convoy (three 

transports, one light cruiser, and three destroyers) accompanied by a cruiser/

destroyer force (two heavy cruisers and one light cruiser and two destroyers) under 

Admiral Hosogaya. During the battle two Japanese cruisers were damaged; one U.S. 

cruiser and two destroyers also suffered some damage. The battle represented an 

Allied victory, because the Japanese stopped resupplying their garrisons on Kiska 

and Attu with surface ships and only occasionally used their submarines. Because 

of the remoteness of the area and the difficult weather conditions the Allies were 

unable to recapture the western Aleutians until mid-1943. On 11 May, the Allied 

forces invaded Attu; all enemy resistance ended on 29 May. The Allies invaded 

Kiska with some thirty-four thousand troops on 15 August 1943, only to find that 

the Japanese forces had been secretly evacuated on 28 July. The U.S. Army aircraft 

had bombed abandoned positions for almost three weeks. Afterward, until the end 

of the war, the Allies used the bases in the western Aleutians to mount numerous 

air raids against the Japanese forces deployed in the Kurils. The Japanese were also 

forced to deploy relatively large ground forces and aircraft to the Kurils because of 

fear of Allied invasion.

Results and Aftermath

Japanese losses in the Midway operation were extremely high. They had lost four 

frontline carriers, 253 aircraft, and one heavy cruiser. In addition, one heavy cruiser 

had been heavily damaged and one destroyer had suffered moderate damage, while 

one battleship, destroyer, and oiler had suffered slight damage. Some sources claim 

that the Japanese lost 332 aircraft, including 280 that went down with the carriers.371

About 150 Japanese pilots were saved, but the Japanese had lost some 3,500 men. In 

contrast the United States had only ninety-two officers and 215 men killed. However, three carrier air groups had been decimated.372 American losses in aircraft had 

been heavy—147 shot down.373

The IJN and the government faced a serious problem regarding how to present 

the news of the losses at Midway to the Japanese public. On 10 June, the IJN briefed 

the Imperial Liaison Conference on the results of the Midway operation. The decision was made there to conceal the true extent of the catastrophe. Except for Emperor Hirohito and top members of the court, few civilians were told the extent of 

the Japanese losses.374 The Midway operation was described to the public as a major 
J

victory. On 10 June, the Navy Ministry was directed to list Japanese losses as one 

carrier sunk, one carrier and cruiser heavily damaged, and thirty-five aircraft lost. 

Five days later, Admiral Ugaki announced that “except for those made public by the 

Naval General Staff nothing should be revealed about the Midway and the Aleutian 

operations within as well as outside of the Navy.” The navy informed its rank and 

file that the carrier Kaga had been sunk and the carrier Sōryū and heavy cruiser 

Mikuma heavily damaged. The ships’ names would not be announced publicly. 

Eventually a directive was issued that the names of Kaga, Sōryū, and Mikuma

would be struck from the register at a suitable opportunity and that Akagi and 

Hiryū would remain on the register but listed as unmanned. The names of those 

killed in action would be gradually released to the families but without mentioning 

the names of the ships on which they had served.375

Conclusion and Operational Lessons Learned

The Japanese conducted the Midway-Aleutians operation in two separate but adjacent theaters of operations. Both operations were almost purely naval, although 

some army units took part in each. In contrast, the U.S. defense of Midway (and the 

Hawaii area) and the Aleutians (and Alaska area) was a more multiservice, or joint, 

effort. Yet the U.S. Pacific Fleet had a dominant role in both operations. 

The Midway-Aleutians operation was an all-or-nothing effort on the part of 

Yamamoto to force the U.S. Pacific Fleet to come out and fight a decisive battle. He 

achieved that purpose but was himself decisively beaten. In what is popularly called 

the battle of Midway of 4–7 June 1942, the IJN lost four large carriers, with many 

aircraft and combat-experienced pilots. These losses were hard to replace. However, 

most important of all was that the battle of Midway marked the beginning of the 

end for the IJN. Its aura of invincibility was shattered, for all to see. The battle of 

Midway represented the turn of the tide in the war in the Pacific and began a chain 

of events that eventually led to the unconditional surrender of Japan in August 1945.

Formally, the Naval General Staff was solely responsible for developing strategy and strategic planning in the IJN. However, that responsibility was in practice 

shared with the Combined Fleet staff, led by Admiral Yamamoto. Because of his 

enormous prestige and influence in the IJN, especially in the aftermath of the highly successful surprise attack on Pearl Harbor, Yamamoto dominated Japanese naval 

strategy in the spring of 1942. Yamamoto too often imposed his will on the Naval 

General Staff. Among his biggest flaws as a naval operational commander were 

rigidity in planning, a propensity to fragment and then widely disperse major force 

elements, and attempts to accomplish multiple objectives almost simultaneously. 

Yamamoto applied the principle of using overwhelming force at the decisive time 

and place to an extreme. The operation as ordered by the Imperial General Headquarters represented a compromise between the Combined Fleet and the Naval 
J

General Staff—a dual major offensive naval/joint operation conducted over vast 

distances. IGHQ made a major error in ordering both operations to be conducted 

simultaneously instead of sequencing them, scheduling the Aleutians operation for 

some time after the successful completion of the Midway operation. 

Strategic or operational objectives should be determined on the basis of thorough 

analysis of the enemy’s factors of space, time, and force. The operational commanders and their staffs should then evaluate friendly factors of space, time, and force, 

and balance them, individually and collectively, with the respective strategic or operational objectives. Any serious imbalance or disconnect should result in either the 

scaling down, modification, or even change or abandonment of a particular strategic 

or operational objective; otherwise, there will be a danger of a serious setback or even 

defeat. The strategic level of command alone should determine strategic objectives to 

be accomplished; operational commanders should not be allowed to drive—or worse, 

dominate—the determination of strategic objectives or the timing of their accomplishment. The planning process at each level of command should be centralized, but the 

execution of the plan should be decentralized. This is especially critical at the strategic and operational levels; otherwise, the result is a compromise plan and greatly 

increased likelihood of failure.

The Japanese plans for both the Midway and the Aleutians operations were 

overly complex. Their execution was based on a rigid timetable. This rigidity in 

thinking is also shown in the prescribed methods for fighting a “decisive battle.” 

Several such methods were prepared for the Midway operation, each based on a 

scripted scenario rather than a running estimate, in case of radical changes in the 

tactical or operational situation. Hence, the flexibility necessary to react to unforeseen events and fleeting opportunities was sorely lacking. Operation plans should 

be simple and flexible. The more complex the plan, the higher the likelihood of failure. Pre-scripted responses to drastic changes in the operational or tactical situation 

should be avoided. Maximum freedom of action should be given to commanders on 

the scene of action to make decisions based on the situation as it develops. 

The original operational idea envisaged using the landing on Midway as a lure 

to the U.S. Pacific Fleet to come out and engage in a decisive battle. However, this 

operational objective was violated because the First Mobile Force was tied to a certain location for two days and thereby lost flexibility of movement. The reason was 

a faulty assumption about the enemy’s possible reaction. Yamamoto believed that 

the enemy force would not depart its base until after Midway had been attacked. 

Yet the destruction of the enemy’s carrier forces—the true enemy operational center of gravity—should have been the main objective, and everything else should 

have been subordinate to that. 

A defective and inadequate pre-invasion scouting and reconnaissance plan lost 

any opportunity to give warning of the enemy fleet when the submarines were 
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delayed for two days in getting under way. The K operation therefore became critically important for success, but it failed, because it was too rigidly planned to allow 

an alternative when the original plan could not be carried out. 

The Japanese assumptions about the enemy’s strength and probable reactions were 

in general overoptimistic. The enemy was supposed to respond according to the Japanese expectations. Admiral Yamamoto presumed that the U.S. Pacific Fleet was already beaten and that all that was required was to draw the American carrier forces out 

to where their destruction could be completed. The plan for the Midway-Aleutians 

operation was based on the idea of achieving this quickly by massing the overwhelming strength of the Combined Fleet against the enemy’s strongest force at the decisive 

place and time. The Combined Fleet’s planners properly determined that the ultimate 

objective in the Midway operation was the U.S. Pacific Fleet’s carrier striking force, 

whose destruction would achieve the operational objective of the entire operation—

sea control of the eastern part of the Central and North Pacific. The strategic effect of 

defeating the U.S. Pacific Fleet would be, they assessed, to force the United States to 

seek a negotiated peace with Japan. 

In contrast, the ultimate objective of the Aleutians operation, although operational in its scale, was temporary in terms of duration. The Japanese intended only 

to occupy temporarily certain key positions in the western Aleutians. Another, 

less important, objective was to draw enemy forces northward from the MidwayHawaii area—which would seem to contradict Yamamoto’s intent of defeating a major 

part of the U.S. Pacific Fleet in a decisive battle. 

Yamamoto made an unsound operational decision in employing all the available 

strength of the Combined Fleet for the Midway-Aleutians operation. In doing so he 

observed the principle of mass but grossly violated the principle of economy of effort. 

The commitment of a major part of the—not the entire—Combined Fleet would have 

been sufficient (provided that a sound plan was prepared and skillfully executed) to 

accomplish the principal objective in both operations. Also, his planners showed a 

bias toward major surface forces by employing all their available battleships and heavy 

cruisers. For example, the landing on Midway could have succeeded without the presence of the main body, Second Fleet, with its battleships and cruisers. Likewise, the 

inclusion of the Guard Force of battleships and cruisers is hard to justify, especially 

since it was deployed beyond supporting distance of the very forces it was supposed to 

support. Finally, Yamamoto himself should have remained in Tokyo to exercise overall 

control over the Combined Fleet, not gone to sea with the Main Force. 

The operational commander should make judicious decisions in determining the 

size, type, and mix of forces required to accomplish the ultimate objective of a major 

operation or campaign. Normally, not all available forces should be employed; the 

principle of economy of effort should be applied. Unnecessarily large forces greatly 

complicate the planning, preparation, and execution of the operation.
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The operational idea for the Midway operation lacked creativeness. It was in 

some ways very similar to the ill-fated Port Moresby–Solomons operation. In 

both cases the amphibious landing was to “lure” the enemy out for a “decisive 

battle,” in which it was a given that the Japanese would be victorious. The Japanese apparently did not consider, or prepare a plan for, operational deception. 

The operational idea (scheme) for a major operation should be creative and thereby avoid past patterns. It should ensure the speed of execution of an operation. It 

should present the enemy with multiple threats. A sound operational idea should 

also include whenever possible operational deception. No one is strong enough at a 

decisive place and time.

In planning for the Midway operation, the Japanese violated the principle of 

objective, as noted above, by tying the First Mobile Force for two days to an area 

northwest of Midway. They allowed a rigid timetable for the landing to restrict 

severely the First Mobile Force’s movements just when the need to engage enemy 

carriers required from Nagumo flexibility in handling his carrier groups. The 

accomplishment of the ultimate operational objective should dominate at all times 

both the planning and the execution of a major operation. Major or minor tactical 

objectives should not be allowed to endanger the accomplishment of the ultimate 

objective. Major tactical commanders should have sufficient freedom to act—that 

is, authority to modify or change tasks, as long as they remain within the framework of the higher commander’s intent.

The timing of the entire Midway-Aleutians operation was based on conditions—specifically, the phase of the moon—favorable to the landing. Yet the 

landing was only a major tactical objective and hence secondary to the ultimate 

objective of the Midway operation, obtaining sea control through the destruction 

of the enemy carrier striking forces. Major and minor tactical objectives that are 

not part of the operational objective have lesser importance. The timing of the entire 

major operation should not be based on the conditions required to accomplish such 

subordinate objectives. 

The Japanese expected that their attack on Midway would surprise the enemy. 

They made a fatal miscalculation in assuming, as has been seen, that the enemy 

would not react until the landing took place. Apparently, no thought was given 

to the possibility that this assumption might be wrong. Success should not depend 

solely on achieving surprise. The commander should not assume that certain things 

will not happen without accurate and reliable knowledge of the enemy plans and 

movements.

The Japanese underestimation of the enemy and overestimation of the enemy’s 

likelihood of following the Japanese narrative were shown in the planning for the 

Midway-Aleutians operation. The plan included “sequels” (actions to be taken 

after a given objective is accomplished) but not “branches” (alternative courses 
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of action should the original plan be derailed or be rendered unexecutable by 

enemy action or one’s own mistakes). A sound operation plan should invariably 

include alternative plans, or branches. No plan survives the first contact with the 

enemy. The enemy has a will of his own and can act and react unpredictably, even 

in ways that one might perceive as irrational. 

The Japanese commanders had fairly good knowledge of the situation on Hawaii and Midway but not of precise locations and movements of the enemy carriers. The Japanese continuously monitored radio transmissions, but their inability 

to break the U.S. codes greatly limited their ability to learn the enemy’s intentions. For the Aleutians, their knowledge of the situation was very rudimentary.

The majority of the Japanese forces assigned to the Midway-Aleutians operation 

were deployed and in combat almost continuously between the end of November 

1941 and the end of April 1942. In addition, one carrier group with its escort, 

which had taken part in the Port Moresby–Solomons operation, did not return 

to home waters until the third week in May 1942. The Combined Fleet urgently 

required an “operational pause,” a period between the end of one major operation 

and the start of the next. All its forces, the carriers in particular, had to undergo 

maintenance and repairs and to replace personnel. They also needed sufficient 

time for rehearsals of the plans for the Midway-Aleutians operation, in a series 

of small and large exercises. Yet Yamamoto was unwilling to change the N-Day 

to allow all this. The result was that most of the Combined Fleet was not properly prepared for Midway and the Aleutians operations. Operational commanders 

should ensure that adequate time is given to preparing their forces for forthcoming 

operations. Otherwise, no matter how good the plan, the entire effort might well 

fail. The timing of the operation should be based also on the time needed for preparations rather than on other factors. 

The Combined Fleet prepared and conducted a four-day war game to test the 

plan for the Midway-Aleutians operations. However, the game’s entire scenario 

was pre-scripted and therefore of limited value. The war game was essentially 

used to justify the plan as presented by Ugaki and his planners. The war game was 

not used to assess objectively the overall plan and its main elements and identify 

its weaknesses, so as to make necessary changes. War games when properly understood and conducted can be extremely useful in identifying the weaknesses in plans 

and orders. Pre-scripted outcomes should not be used to justify decisions already 

made or to confirm validity of plans. Concerns expressed by the participants of a 

war game should be given fair hearings and not simply dismissed.

In contrast to the Japanese, the American command organization ensured unity 

of effort by achieving unity of command. Nimitz was both a theater-strategic and 

operational commander. He had full operational control of the Navy and Army 

forces within his area of responsibility. As the CINCPac he also had full command 
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and control over all task forces—that is, major tactical commanders. He was 

nominally subordinate not only to the JCS but also to Admiral King, who was 

COMINCH/CNO. The theater commands should be established in advance, preferably in peacetime. This is the only proven way to ensure centralized planning of campaigns and of major operations, and then their decentralized execution. Theater command also ensures centralization of all theaterwide functions, such as intelligence, 

logistics, and protection. Normally, however, a theater-strategic commander should not 

be at the same time theater-of-operations commander or the commander of theater/

numbered forces. 

The American operational and tactical commanders had knowledge and understanding of the situation much superior to those of their Japanese counterparts. 

COMINT proved its value by giving Nimitz and King accurate, timely, and reliable knowledge of the enemy’s current and future operations. This in turn allowed 

Nimitz and his staff to fuse tactical and strategic information into operational 

intelligence. Without his firm belief in the accuracy of information provided by 

Rochefort and Layton, Nimitz would not have been able to concentrate in time 

his numerically smaller forces in the Hawaii-Midway area. Using the information 

obtained by COMINT, Nimitz and King made a number of organizational and 

operational decisions in May 1942 that would significantly contribute to the successful defense of the Hawaii-Midway area and the Aleutians. Knowledge of the 

enemy’s intentions through decryption of messages is of inestimable value for timely 

and sound operational decisions prior to the start of a major operation or campaign. 

Yet COMINT has little value once combat actions start. Once the opposing forces are 

in contact, the outcome depends on the speed and soundness of the commanders’ decisions, on their judgment and experience, and on the skills and courage of the sailors 

and airmen. One should be always aware that a clever enemy might use messages 

to gain a decisive advantage by feigning intentions—that is, practicing deception to 

achieve surprise. 

Nimitz’s operational plans for defense of Hawaii-Midway and the Aleutians 

were short, simple, and straightforward. They were also flexible in execution. They 

were largely based on the information gained from COMINT. One could take issue, however, with Nimitz’s decision to detach cruisers/destroyers to TF 8. The 

Japanese forces assigned to the Northern Area Force were both numerically and 

qualitatively superior, so assigning a few more cruisers and destroyers to Admiral Theobald would not make any difference. These ships were badly needed for 

protection of the carriers in the Hawaii-Midway area. In contrast to the American 

plans, the Japanese plan for the Midway operation began to unravel almost at the 

very beginning. The cancellation of the second K operation made it impossible to 

obtain critically important reconnaissance of Pearl Harbor. The scout submarines, 

having reached their assigned patrolling lines two days late, missed the transit of 
J

the enemy carrier forces to their operating area north of Midway. Timely information on the whereabouts and movements of the enemy forces is critical for the success 

of a major operation. Optimally, such information should be obtained from diverse 

sources. Reliance on a single source of information should be avoided.

The Japanese forces were separated by several hundreds of miles—that is, 

they were beyond mutually supporting distances. All had to maintain strict radio 

silence. Yamamoto was for all practical purposes an observer from the time the 

Main Force left its base until the first encounter with enemy forces. One’s force elements should be deployed within mutually supporting distances of other forces; otherwise, the entire operation might result in a serious setback or even defeat.

The most decisive event in the entire Midway operation was the clash of the 

opposing carrier forces on 4 June. Spruance made a quick and sound decision to 

launch a full-load attack against the enemy carriers. This decision was risky, because the enemy carriers were some 155 miles away and the maximum effective 

range of the U.S. carrier aircraft was only about 175 miles. By sheer coincidence, 

when the U.S. aircraft came over their targets the Japanese carriers had their decks 

full of aircraft being prepared to strike. The first attacks resulted in fatal damage to 

three out of four Japanese carriers. 

Nagumo’s performance on 4 June has been much criticized, and justifiably 

so. He clearly did not act with the speed and aggressiveness that the situation demanded. One error was that he did not employ an adequate search disposition in 

the morning of 4 June. If he had used two-plane searches, the enemy force would 

probably have been detected. He made initially a sound decision to withhold half 

of his air group in reserve in case the need arose to engage enemy surface forces; 

the other half was sent to attack Midway. However, a more serious mistake was assembling the strikes from proportionate numbers of aircraft from each carrier. Although this considerably increased the speed for launching and recovering aircraft 

it also greatly increased the vulnerability of the entire First Mobile Force in case of 

a sudden appearance of the enemy carrier force. The Japanese were too sure that 

the enemy carriers would appear only after the landing on Midway. A much better 

solution would have been to have each group composed of aircraft from only two 

carriers. Obviously, however, Nagumo’s single greatest error was his decision to 

complete the recovery and rearming of the air group that had attacked Midway and 

only then launch an all-out attack, with aircraft from all four carriers. He should 

have launched an immediate attack on the enemy carrier force with all available aircraft (at the time he made the decision Nagumo knew about the presence of only a 

single carrier force), regardless of whether they were properly armed and protected 

by fighters or not. This decision is difficult to justify, because at the time Nagumo 

knew that only a single enemy carrier was present, not all three. As it happened, 

when the enemy aircraft attacked, Nagumo’s carriers were caught flat-footed and 
J

eventually all four were sunk. Yet this outcome of the clash between the opposing 

carrier forces was not by any means preordained. Had Spruance or Nagumo made 

different decisions at critical times, the results for each side would have been probably different too. 

Operational commanders should make quick and good decisions instead of waiting and making the “best” one. Normally, the best way to proceed is to use overwhelming force at the decisive place and time. Even this tenet should not be dogmatically 

applied, however; commanders base their decisions on the facts of the situation. Very 

often speed of action is much more important than mass. Also, the validity of a commander’s decision should be evaluated on the basis not of knowledge gained after the 

fact but of that which a commander had at the time. 

Spruance was unjustifiably criticized by some for not pursuing the enemy carrier force in the night of 4–5 June. Yet Spruance made the right call, in temporarily withdrawing eastward rather than risking a night encounter with a much 

stronger force. Spruance had no way of knowing that Yamamoto had in fact directed several major groups, including battleships, to seek a decisive battle with 

him; nor did Spruance know precisely at that stage of the war how superior the 

Japanese really were in night gunnery and torpedo tactics. His decision can be 

simply explained by his sense that TF 16, with its six cruisers and nine destroyers, 

was not a match for any enemy force that included battleships, heavy cruisers, 

and destroyers in a night engagement. 

In the Aleutians, the Japanese were relatively more successful than in the Midway operation. With the exception of attack on Adak, they accomplished all the 

objectives stipulated in their plan. The Japanese superiority over the weak U.S. 

forces was overwhelming. Yet Admiral Theobald facilitated their success by focusing on the defense of the eastern, rather than western, Aleutians. The reason 

was Theobald’s rejection of the intelligence obtained through COMINT and received through his superior, Nimitz. Theobald decided to be his own intelligence 

officer and proceeded to base his decisions on false assumptions. Subordinate 

commanders should integrate intelligence received from the higher commander, in 

the absence of their own sources of information on the enemy. They should not 

make planning assumptions based on little or no knowledge of the enemy or their 

intuition. 

One of the major reasons the Japanese met defeat in the Midway operation was 

their almost unbounded faith in their own superiority and omnipotence. They 

convinced themselves that in any encounter with the U.S. Pacific Fleet their success 

was ensured. In both the planning and the execution of the Midway-Aleutians operation, Yamamoto failed as the operational commander. The outcome of the MidwayAleutians operation is a classic case of how superiority can be easily squandered 

if the operational commander thinks tactically rather than operationally. 
J

Professional arrogance is a dangerous trait. It often leads to hubris, a complete loss 

of connection with reality. No enemy should ever be underestimated. He has a will 

of his own and will not conform to one’s expectations. Even enormous technological 

and numerical superiority is often inadequate in itself to ensure success in a major 

operation or campaign. One of the first and foremost prerequisites of success for the 

operational commander is to maintain an operational, vice tactical, perspective on 

the situation. The outcome of any war—and war at sea is no exception—depends 

primarily on the quality of the human factor, not on one’s technological or numerical 

superiority.

NOTES 1 Headquarters, Army Far East, U.S. Far East Command, Aleutian Naval Operations, March 1942–

February 1943, Javpanese Monograph 88 (n.p. [Tokyo]: Military History Section, n.d.), in U.S. Army 

Dept., War in Asia and the Pacific, vol. 5, The Naval 

Armament Program and Naval Operations (Part II)

(New York: Garland for Chief of Military History, 

1980) [hereafter Japanese Monograph 88], p. 6.

2 Ibid., p. 2.

3 John K. Wright, “Pacific Islands,” Geographical 

Review 32, no. 3 (July 1942), p. 484.

4 David R. Ellis, The History and Strategic Importance of the Midway Islands (Carlisle Barracks, Pa.: 

U.S. Army War College, 2002), p. 2.

5 Richard W. Bates, The Battle of Midway including 

the Aleutian Phase, June 3 to June 14, 1942: Strategical and Tactical Analysis (Newport, R.I.: Naval 

War College for the Bureau of Naval Personnel, 

1948), pp. 7–8.

6 Japanese Monograph 88, p. 4.

7 Carol A. Wilder, Weather as the Decisive Factor of 

the Aleutian Campaign, June 1942–August 1943 

(Fort Leavenworth, Kans.: U.S. Army Command 

and General Staff College, 1993), p. 18.

8 Cited in ibid.

9 U.S. Navy Dept., The Aleutians Campaign, June 

1942–August 1943 (Washington, D.C.: Naval Historical Center, 1993), p. 3.

10 Bates, Battle of Midway, p. 5.

11 Ibid., p. 9.

12 U.S. Navy Dept., Aleutians Campaign, p. 3.

13 Jonathan Parshall and Anthony Tully, Shattered 

Sword: The Untold Story of the Battle of Midway

(Washington, D.C.: Potomac Books, 2005), p. 5.

14 Bates, Battle of Midway, p. 16.

15 Ibid., p. 7.

16 Ibid., p. 45.

17 Ibid.

18 Ibid., p. 46.

19 Charles A. Willoughby et al., eds., Reports of General MacArthur, vol. 2, part 1, Japanese Operations 

in the Southwest Pacific Area (Washington, D.C.: 

U.S. Government Printing Office [hereafter GPO], 

January 1966; facsimile, 1994), p. 319.

20 U.S. Strategic Bombing Survey (Pacific), The Campaigns of the Pacific War (Washington, D.C.: GPO 

for Naval Analysis Division, 1946), p. 2.

21 Parshall and Tully, Shattered Sword, p. 23.

22 Mitsuo Fuchida and Masatake Okumiya, Midway: 

The Battle That Doomed Japan—the Japanese 

Navy’s Story (Annapolis, Md.: Naval Institute Press, 

1955), p. 74.

23 Ibid., pp. 76–77.

24 Ibid., p. 74.

25 Parshall and Tully, Shattered Sword, p. 23.

26 Ibid., p. 24.

27 Fuchida and Okumiya, Midway, p. 75.

28 Ibid., p. 76.

29 Ibid., pp. 48–49, 54.

30 Hiroyaki Agawa, The Reluctant Admiral: Yamamoto and the Imperial Navy (Tokyo: Kodansha 

International, 1979), p. 293.
J

31 Japanese Monograph 88, pp. 6–7.

32 Gordon W. Prange, with Donald M. Goldstein 

and Katherine V. Dillon, Miracle at Midway

(Harmondsworth, U.K.: Penguin Books, 1983), p. 14.

33 Parshall and Tully, Shattered Sword, p. 28.

34 Fuchida and Okumiya, Midway, pp. 50–51.

35 Ibid., p. 54.

36 Ibid., p. 57.

37 Ibid., p. 58.

38 John B. Lundstrom, The First South Pacific Campaign: Pacific Fleet Strategy December 1941–June 

1942 (Annapolis, Md.: Naval Institute Press, 1976), 

p. 45.

39 Fuchida and Okumiya, Midway, p. 60.

40 Japanese Monograph 88, pp. 6–7.

41 Ibid., p. 57.

42 Fuchida and Okumiya, Midway, p. 61.

43 “Battle of the Coral Sea: Overview and Preparations 

for Battle,” The Pacific War, pp. 5–6, www.pacificwar

.org.au/.

44 Fuchida and Okumiya, Midway, p. 61. 

45 Parshall and Tully, Shattered Sword, p. 24. 

46 “Battle of the Coral Sea: Overview and Preparations 

for Battle,” p. 5.

47 Japanese Monograph 88, p. 57.

48 Toshikaze Ohmae, “The Battle of Savo Island,” in 

The Japanese Navy in World War II: In the Words 

of Former Japanese Naval Officers, ed. David C. 

Evans, 2nd ed. (Annapolis, Md.: Naval Institute 

Press, 1986), pp. 213–14; Samuel E. Morison, The 

Two-Ocean War: A Short History of the United 

States Navy in the Second World War (Boston: Little, 

Brown, 1963), p. 140.

49 Japanese Monograph 88, p. 8.

50 General Headquarters, Supreme Commander 

Allied Powers, Midway Operations, May–June 

1942, Japanese Monograph 93 (Washington, D.C.: 

Military Intelligence Section, General Staff, Allied 

Translation and Interpreter Section, 1947) [hereafter 

Japanese Monograph 93], p. 3.

51 Fuchida and Okumiya, Midway, p. 117.

52 Parshall and Tully, Shattered Sword, pp. 13–14.

53 Ibid., p. 13.

54 Japanese Monograph 93, pp. 3–4.

55 Ibid., p. 4.

56 Fuchida and Okumiya, Midway, p. 84.

57 Japanese Monograph 88, p. 25.

58 Cited in John B. Lundstrom, Black Shoe Carrier 

Admiral: Frank Jack Fletcher at Coral Sea, Midway, 

and Guadalcanal (Annapolis, Md.: Naval Institute 

Press, 2006), p. 220.

59 Cited in James R. Parrington, “Operational Failures 

Caused by Arrogant Leaders” (Naval War College, 

Newport, R.I., 31 October 2008), p. 8.

60 Fuchida and Okumiya, Midway, p. 78.

61 U.S. Army Dept., Submarine Operations in Second 

Phase Operations, Part I: April–August 1942,

Japanese Monograph 110 (Washington, D.C.: Chief 

of Military History, March 1952) [hereafter Japanese 

Monograph 110], p. 21.

62 Fuchida and Okumiya, Midway, p. 120; 

Lundstrom, Black Shoe Carrier Admiral, p. 219.

63 Japanese Monograph 110, pp. 21–22.

64 Fuchida and Okumiya, Midway, p. 89.

65 Prange, Miracle at Midway, p. 32.

66 Fuchida and Okumiya, Midway, pp. 85–86.

67 Ibid., p. 87.

68 Japanese Monograph 110, p. 17.

69 Cited in Prange, Miracle at Midway, p. 33; Fuchida 

and Okumiya, Midway, pp. 233–34; Bates, Battle of 

Midway, p. 20.

70 Cited in Prange, Miracle at Midway, p. 53.

71 Bates, Battle of Midway, pp. 28, 30.

72 Ibid., p. 31.

73 Ibid., pp. 28, 32.

74 Ibid., pp. 25–26.

75 Fuchida and Okumiya, Midway, pp. 86–87.

76 Japanese Monograph 110, p. 16.

77 Bates, Battle of Midway, pp. 12, 17.

78 Ibid., pp. 17–18.

79 Fuchida and Okumiya, Midway, p. 79.

80 Japanese Monograph 88, p. 3.

81 Ibid., p. 9.

82 Ibid., pp. 9, 11.

83 Ibid., pp. 32–34.

84 Samuel E. Morison, History of United States Naval 

Operations in World War II, vol. 4, Coral Sea, Midway and Submarine Actions, May 1942–August 1942

(Boston: Little, Brown, September 1949; repr. March 

1984), p. 169.

85 Bates, Battle of Midway, p. 20.

86 Japanese Monograph 88, pp. 16–17.

87 Ibid., pp. 19–20.

88 Japanese Monograph 93, p. 9. 

89 Ibid.

90 Fuchida and Okumiya, Midway, p. 85.

91 Japanese Monograph 110, p. 30.

92 Japanese Monograph 88, pp. 32–33, 42.

93 Ibid., p. 16.

94 Ibid., pp. 16, 25.

95 Ibid., pp. 21–22, cited in Lundstrom, Black Shoe 

Carrier Admiral, p. 220.

96 Bates, Battle of Midway, pp. 21–22.

97 Lundstrom, Black Shoe Carrier Admiral, p. 219.

98 Fuchida and Okumiya, Midway, p. 85.

99 Ibid., p. 91.

100 Ibid., pp. 61–62.

101 Japanese Monograph 93, p. 11.

102 Japanese Monograph 88, p. 32.
J

103 U.S. Navy Dept., The Japanese Story of the Battle of 

Midway, OPNAV P32-1002 (Washington, D.C.: Office of Naval Intelligence, June 1947), p. 6, available 

at www.history.navy.mil/.

104 Fuchida and Okumiya, Midway, p. 108; U.S. Navy 

Dept., Japanese Story of the Battle of Midway, p. 13.

105 Bates, Battle of Midway, p. 13.

106 U.S. Navy Dept., Japanese Story of the Battle of Midway, p. 6.

107 Fuchida and Okumiya, Midway, p. 109.

108 Bates, Battle of Midway, p. 13.

109 Fuchida and Okumiya, Midway, p. 109.

110 Ibid., p. 108.

111 “Japanese Planning and Preparations for the 

Midway Offensive,” The Pacific War, p. 2, www

.pacificwar.org.au/.

112 Bates, Battle of Midway, p. 13.

113 Fuchida and Okumiya, Midway, p. 108.

114 Ibid.; U.S. Navy Dept., Japanese Story of the Battle of 

Midway, p. 6.

115 Bates, Battle of Midway, p. 12.

116 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 168.

117 Japanese Monograph 88, pp. 29–30.

118 Ibid., pp. 30–31.

119 Ibid., p. 4; Prange, Miracle at Midway, p. 157.

120 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 168.

121 Japanese Monograph 88, p. 5.

122 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 168.

123 Japanese Monograph 88, p. 5.

124 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 168; Prange, Miracle at 

Midway, p. 157.

125 Fuchida and Okumiya, Midway, p. 91.

126 U.S. Navy Dept., Japanese Story of the Battle of Midway, p. 9.

127 Japanese Monograph 88, p. 8.

128 Ibid., pp. 36–37.

129 Ibid., p. 49.

130 Ibid., pp. 96–97.

131 Ibid., p. 97.

132 Edwin T. Layton, “And I Was There”: Pearl Harbor 

and Midway—Breaking the Secrets (New York: 

Quill / William Morrow, 1985), p. 407.

133 Fuchida and Okumiya, Midway, pp. 98–99.

134 Lundstrom, Black Shoe Carrier Admiral, pp. 220–21.

135 Fuchida and Okumiya, Midway, p. 62.

136 Henry F. Schorreck, Battle of Midway: 4–7 June 

1942: The Role of COMINT in the Battle of Midway,

SRH-230 (Washington, D.C.: Naval Historical Center, n.d.), p. 4, available at www.history.navy.mil/. 

137 Frederick D. Parker, A Priceless Advantage: U.S. 

Navy Communications Intelligence and the Battles of 

Coral Sea, Midway, and the Aleutians (Fort George 

G. Meade, Md.: Center for Cryptologic History, 

National Security Agency, 1993), p. 17, available at 

www.centuryinter.net/.

138 Schorreck, Battle of Midway, p. 13.

139 Layton, “And I Was There,” p. 408.

140 Fuchida and Okumiya, Midway, p. 89.

141 Cited in Parker, Priceless Advantage, p. 43.

142 The Role of Radio Intelligence in the AmericanJapanese War, vol. 1, part 2 of 2, entry A1 9002, 

Studies on Cryptology, 1917–1977, p. 1, SRH012, 

container 1, Record Group [hereafter RG] 457, 

Records of the National Security Agency / Central 

Security Service, National Archives and Records 

Service, College Park, Md. [hereafter NARA].

143 Cited in Parker, Priceless Advantage, pp. 41–42.

144 Ibid., p. 44.

145 Role of Radio Intelligence in the American-Japanese 

War, p. 264.

146 Parker, Priceless Advantage, p. 45.

147 Ibid., p. 43.

148 Role of Radio Intelligence in the American-Japanese 

War, p. 264.

149 Parker, Priceless Advantage, p. 45.

150 Role of Radio Intelligence in the American-Japanese 

War, p. 265.

151 Ibid., p. 2.

152 Ibid., p. 266.

153 Parker, Priceless Advantage, p. 42.

154 Ibid., pp. 43–44. 

155 Role of Radio Intelligence in the American-Japanese 

War, p. 266(b).

156 Ibid., pp. 267–68.

157 Parker, Priceless Advantage, p. 45; Role of Radio Intelligence in the American-Japanese War, pp. 267–68.

158 Parker, Priceless Advantage, p. 45.

159 Schorreck, Battle of Midway, p. 17.

160 Role of Radio Intelligence in the American-Japanese 

War, p. 271.

161 Parker, Priceless Advantage, p. 46.

162 Schorreck, Battle of Midway, p. 19.

163 Parker, Priceless Advantage, p. 46.

164 Schorreck, Battle of Midway, p. 31.

165 “CNO Summaries (of Radio Intelligence) Japanese 

Naval Activities (14 April 1942–30 June 1942),” p. 

1, entries SRNS 0001–SRNS 0073, box 01, RG 457, 

Records of the National Security Agency / Central 

Security Service, United States Navy Records Relating to Cryptology, 1918–1950, NARA.

166 Parker, Priceless Advantage, p. 46.

167 Ibid., pp. 46–47.

168 “CNO Summaries (of Radio Intelligence),” pp. 1–2

169 Role of Radio Intelligence in the American-Japanese 

War, p. 275.

170 “CNO Summaries (of Radio Intelligence),” p. 1.

171 Parker, Priceless Advantage, p. 47.
J

172 Ibid., pp. 42, 48.

173 “CNO Summaries (of Radio Intelligence),” p. 1.

174 Schorreck, Battle of Midway, p. 24.

175 Role of Radio Intelligence in the American-Japanese 

War, p. 3.

176 Ibid., p. 280.

177 “CNO Summaries (of Radio Intelligence),” pp. 1–2.

178 Ibid., p. 1.

179 Ibid., p. 2.

180 Schorreck, Battle of Midway, p. 20.

181 Parker, Priceless Advantage, p. 50.

182 Elmer B. Potter, Nimitz (Annapolis, Md.: Naval 

Institute Press, 1976), p. 79.

183 Schorreck, Battle of Midway, p. 22; cited in Parker, 

Priceless Advantage, p. 51.

184 Parker, Priceless Advantage, p. 51.

185 “CNO Summaries (of Radio Intelligence),” p. 1.

186 Schorreck, Battle of Midway, p. 25.

187 Parker, Priceless Advantage, p. 51.

188 “CNO Summaries (of Radio Intelligence),” for 21 

May 1942, p. 1.

189 Role of Radio Intelligence in the American-Japanese 

War, p. 4.

190 Ibid., p. 299.

191 Parker, Priceless Advantage, p. 52.

192 “CNO Summaries (of Radio Intelligence),” for 23 

May 1942, p. 1.

193 Ibid., for 24 May 1942, p. 1.

194 Ibid.

195 Schorreck, Battle of Midway, p. 27.

196 Parker, Priceless Advantage, p. 53.

197 Role of Radio Intelligence in the American-Japanese 

War, pp. 309, 311; “CNO Summaries (of Radio Intelligence),” for 24 and 25 May 1942, p. 1.

198 “CNO Summaries (of Radio Intelligence),” for 26 

May 1942, p. 1.

199 Parker, Priceless Advantage, pp. 54–55.

200 Bates, Battle of Midway, p. 39.

201 Thomas B. Buell, Master of Sea Power: A Biography 

of Fleet Admiral Ernest J. King (Annapolis, Md.: 

Naval Institute Press, 1980), p. 201.

202 Ibid., p. 200.

203 Ibid., p. 201.

204 Ibid.

205 Cited in Parker, Priceless Advantage, p. 49.

206 Bates, Battle of Midway, p. 40.

207 Parker, Priceless Advantage, pp. 53–54.

208 Bates, Battle of Midway, p. 39.

209 Lundstrom, Black Shoe Carrier Admiral, pp. 223–24. 

210 Thomas B. Buell, The Quiet Warrior: A Biography 

of Admiral Raymond A. Spruance (Annapolis, Md.: 

Naval Institute Press, 1974), pp. 139–40; Prange, 

Miracle at Midway, p. 83.

211 Lundstrom, Black Shoe Carrier Admiral, p. 223. 

212 Potter, Nimitz, p. 85.

213 Lundstrom, Black Shoe Carrier Admiral, p. 225. 

214 Potter, Nimitz, p. 87.

215 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 161.

216 Parker, Priceless Advantage, p. 55.

217 Buell, Quiet Warrior, p. 136. 

218 “Admiral C. W. Nimitz, USN, Organizes the 

Forces under His Command to Prevent the Capture 

and Occupation of Midway by Enemy Forces,” 

Operation Plan No. 29-42, 27 May 1942, p. 3, folder 

CINCPAC Operation Plan 29-42, 27 May 1942, 

CINCPAC May 1942 to October 1942, box 21, RG 

38, Records of the Office of the Chief of Naval Operations, Records Relating to Naval Activity during 

World War II: Plans, Orders and Related Documents, NARA [hereafter “Admiral C. W. Nimitz, 

USN, Organizes the Forces”].

219 Ibid., pp. 3–4.

220 Commander in Chief, U.S. Pacific Fleet, After Action Report, 28 June 1942, p. 4, serial 01849, “Battle 

of Midway,” part I, scanned by MilSpecManuals, 

Cloudcroft, N.Mex.

221 Bates, Battle of Midway, p. 65.

222 Ibid., p. 72.

223 “Admiral C. W. Nimitz, USN, Organizes the Forces,” 

p. 4.

224 Ibid., p. 6.

225 Lundstrom, Black Shoe Carrier Admiral, p. 227.

226 Potter, Nimitz, p. 87.

227 “Admiral C. W. Nimitz, USN, Organizes the Forces,” 

p. 6.

228 Ibid.

229 Bates, Battle of Midway, p. 67.

230 “Admiral C. W. Nimitz, USN, Organizes the Forces,” 

p. 6.

231 Operation Plan No. 29-42, 27 May 1942, pp. 7–8, 

folder CINCPAC Operation Plan 29-42, 27 May 

1942, CINCPAC May 1942 to October 1942, box 21, 

RG 38, Records of the Office of the Chief of Naval 

Operations, Records Relating to Naval Activity 

during World War II: Plans, Orders and Related 

Documents, NARA.

232 E. P. Forrestel, Admiral Raymond A. Spruance, USN: 

A Study in Command (Washington, D.C.: GPO, 

1966), p. 38.

233 Carl H. Builder, Steven C. Bankes, and Richard 

Nordin, Command Concepts: A Theory Derived from 

Practice of Command and Control (Santa Monica, 

Calif.: RAND, National Defense Research Institute, 

1999), pp. 37–38.

234 Bates, Battle of Midway, p. 50.

235 “Admiral C. W. Nimitz, USN, Organizes the Forces,” 

p. 4.

236 “Admiral C.W. Nimitz, USN, Orders Forces under 

Rear Admiral R. A. Theobald, USN, to Oppose 

the Advance of the Enemy in the Aleutians Alaska 

Area,” Operation Plan No. 28-42, 27 May 1942, p. 

2, folder CINCPAC Operation Plan 28-42, 21 May 
J

1942, CINCPAC May 1942 to October 1942, box 21, 

RG 38, Records of the Office of the Chief of Naval 

Operations, Records Relating to Naval Activity 

during World War II: Plans, Orders and Related 

Documents, NARA.

237 Bates, Battle of Midway, pp. 43–44.

238 Parker, Priceless Advantage, pp. 51–52.

239 Bates, Battle of Midway, p. 44.

240 Ibid., p. 73.

241 U.S. Navy Dept., Aleutians Campaign, p. 5.

242 Bates, Battle of Midway, p. 74.

243 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 171.

244 U.S. Navy Dept., Aleutians Campaign, p. 5.

245 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 170.

246 Ibid., p. 171.

247 Carl L. Boyd, review of Rendezvous at Midway: 

U.S.S. Yorktown and the Japanese Carrier Fleet, by 

Pat Frank and Joseph D. Harrington, Military Affairs

31, no. 3 (Autumn 1967), p. 156.

248 See also Bates, Battle of Midway, p. 82.

249 Ibid., p. 83.

250 Prange, Miracle at Midway, p. 130.

251 Bates, Battle of Midway, p. 83.

252 Ibid., pp. 82–83.

253 Ibid., pp. 22–23.

254 Ibid., pp. 19–20.

255 Ibid., p. 23.

256 Japanese Monograph 88, pp. 49, 56, 64.

257 Bates, Battle of Midway, p. 19.

258 Ibid., p. 62.

259 Ibid., p. 63.

260 Commander in Chief, U.S. Pacific Fleet, After Action Report, p. 4.

261 Lundstrom, Black Shoe Carrier Admiral, p. 233.

262 Buell, Quiet Warrior, p. 143.

263 Bates, Battle of Midway, p. 66.

264 Potter, Nimitz, p. 88.

265 Japanese Monograph 110, p. 23.

266 Fuchida and Okumiya, Midway, p. 121.

267 Japanese Monograph 110, p. 22.

268 Bates, Battle of Midway, p. 21.

269 Fuchida and Okumiya, Midway, p. 122.

270 Japanese Monograph 88, pp. 17–18.

271 Fuchida and Okumiya, Midway, p. 122.

272 Bates, Battle of Midway, pp. 26–27.

273 Lundstrom, Black Shoe Carrier Admiral, p. 237. 

274 Forrestel, Admiral Raymond A. Spruance, USN, p. 

41; “Battle of Midway: 4–7 June 1942, Online Action 

Reports: Commander in Chief, Pacific Fleet, Serial 

01849 of 28 June 1942,” Naval History and Heritage 

Command [hereafter “Online Action Reports: Commander in Chief, Pacific Fleet”], p. 4, www.history

.navy.mil/.

275 Bates, Battle of Midway, p. 76.

276 Forrestel, Admiral Raymond A. Spruance, USN, p. 41.

277 “Online Action Reports: Commander in Chief, 

Pacific Fleet,” p. 4.

278 Bates, Battle of Midway, p. 85.

279 U.S. Navy Dept., Japanese Story of the Battle of Midway, p. 7.

280 Cited in Builder, Bankes, and Nordin, Command 

Concepts, p. 38.

281 Cited in Buell, Quiet Warrior, p. 138.

282 Cited in Builder, Bankes, and Nordin, Command 

Concepts, pp. 31–32.

283 Forrestel, Admiral Raymond A. Spruance, USN, 

p. 39.

284 Bates, Battle of Midway, p. 9.

285 Ibid., p. 84.

286 Lundstrom, Black Shoe Carrier Admiral, p. 241.

287 Bates, Battle of Midway, pp. 86–87.

288 Lundstrom, Black Shoe Carrier Admiral, p. 239.

289 Ibid.

290 “Online Action Reports: Commander in Chief, 

Pacific Fleet,” p. 5.

291 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 103.

292 Buell, Quiet Warrior, p. 145; other sources claim that 

originally, Spruance intended to launch his planes 

at 0900 (by when they would have had only about a 

hundred miles to fly to the enemy carriers) but that 

Browning, his chief of staff, suggested launching an 

attack two hours earlier; Morison, History of United 

States Naval Operations in World War II, vol. 4, p. 

113.

293 Buell, Quiet Warrior, p. 146. 

294 “Battle of Midway: 4–7 June 1942, Online Action 

Reports: Commander Cruisers, Pacific Fleet of 14 

June 1942,” Naval History and Heritage Command,

pp. 1–2, www.history.navy.mil/.

295 Commander in Chief, U.S. Pacific Fleet, After Action Report, p. 10.

296 Ibid., p. 12.

297 “Battle of Midway: 4–7 June 1942, Online Action 

Reports: Commander Task Force Sixteen, Serial 

0144A of 16 June 1942,” Naval History and Heritage 

Command [hereafter “Online Action Reports: Commander Task Force Sixteen”], p. 2, www.history

.navy.mil/.

298 Morison, History of United States Naval Operations 

in World War II, vol. 4, pp. 113–14.

299 “Online Action Reports: Commander Task Force 

Sixteen,” pp. 1–2.

300 Ibid., p. 2.

301 Bates, Battle of Midway, p. 89.

302 Commander in Chief, U.S. Pacific Fleet, After Action Report, p. 8.

303 “Online Action Reports: Commander in Chief, 

Pacific Fleet,” p. 6; Commander in Chief, U.S. Pacific 

Fleet, After Action Report, p. 9; Morison, History of 
J

 United States Naval Operations in World War II, vol. 

4, p. 110; Bates, Battle of Midway, p. 90. 

304 Bates, Battle of Midway, p. 90; Ministry of Defence 

(Navy), War with Japan, vol. 2, Defensive Phase

(London: Her Majesty’s Stationery Office, 1995), p. 

155; Commander in Chief, U.S. Pacific Fleet, After 

Action Report, p. 9.

305 “Online Action Reports: Commander in Chief, 

Pacific Fleet,” p. 6; Morison, History of United States 

Naval Operations in World War II, vol. 4, p. 111; 

Bates, Battle of Midway, p. 91.

306 Fuchida and Okumiya, Midway, pp. 165, 167.

307 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 107.

308 Ibid., p. 102.

309 Fuchida and Okumiya, Midway, pp. 167, 169–70.

310 Potter, Nimitz, p. 105.

311 Parshall and Tully, Shattered Sword, pp. 16–17.

312 Fuchida and Okumiya, Midway, pp. 171, 173.

313 Morison, History of United States Naval Operations 

in World War II, vol. 4, pp. 110, 115.

314 Buell, Quiet Warrior, p. 150.

315 Commander in Chief, U.S. Pacific Fleet, After Action Report, p. 10.

316 Ibid., p. 11.

317 Ibid.; “Online Action Reports: Commander in 

Chief, Pacific Fleet,” pp. 2, 7.

318 “Online Action Reports: Commander Task Force 

Sixteen,” p. 2; Morison, History of United States Naval Operations in World War II, vol. 4, pp. 120–21. 

319 Morison, History of United States Naval Operations 

in World War II, vol. 4, pp. 126–28.

320 Fuchida and Okumiya, Midway, p. 208.

321 Morison, History of United States Naval Operations 

in World War II, vol. 4, pp. 132–33.

322 “Online Action Reports: Commander Task Force 

Sixteen,” p. 2, cited in Buell, Quiet Warrior, p. 150.

323 “Online Action Reports: Commander Task Force 

Sixteen,” p. 2.

324 Fuchida and Okumiya, Midway, p. 209.

325 Bates, Battle of Midway, p. 97.

326 Fuchida and Okumiya, Midway, p. 219.

327 Bates, Battle of Midway, p. 97.

328 Cited in Buell, Quiet Warrior, p. 151.

329 Ibid.

330 Ibid., p. 152.

331 Forrestel, Admiral Raymond A. Spruance, USN, p. 

47; “Online Action Reports: Commander in Chief, 

Pacific Fleet,” p. 3.

332 Buell, Quiet Warrior, p. 153.

333 Ibid., p. 213.

334 Ibid., p. 214.

335 Forrestel, Admiral Raymond A. Spruance, USN, pp. 

49–50.

336 “Online Action Reports: Commander Task Force 

Sixteen,” p. 2.

337 Forrestel, Admiral Raymond A. Spruance, USN, 

p. 50.

338 Ibid.

339 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 142.

340 Fuchida and Okumiya, Midway, p. 217.

341 Ibid., p. 220.

342 Ibid., p. 218.

343 “Online Action Reports: Commander Task Force 

Sixteen,” p. 3.

344 Ibid., p. 4.

345 Ibid., p. 3.

346 “Online Action Reports: Commander in Chief, 

Pacific Fleet,” p. 12.

347 Ministry of Defence (Navy), Defensive Phase,

p. 162.

348 See also, Fuchida and Okumiya, Midway, pp. 

230–31.

349 Forrestel, Admiral Raymond A. Spruance, USN, 

p. 54.

350 Fuchida and Okumiya, Midway, pp. 230–31.

351 Forrestel, Admiral Raymond A. Spruance, USN, 

p. 55.

352 Japanese Monograph 110, p. 31.

353 Ibid.

354 Bates, Battle of Midway, pp. 14–15.

355 Ibid., pp. 9–10. 

356 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 175.

357 Ministry of Defence (Navy), Defensive Phase, p. 168; 

Japanese Monograph 88, p. 45.

358 Japanese Monograph 88, pp. 45–46.

359 Cited in Morison, History of United States Naval 

Operations in World War II, vol. 4, pp. 176–77.

360 Ibid., pp. 181–82.

361 Japanese Monograph 88, p. 47.

362 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 177.

363 Japanese Monograph 88, pp. 39–40.

364 Ibid., pp. 47–48.

365 Ibid., p. 48.

366 Ibid., p. 51.

367 Ibid., p. 34.

368 Morison, History of United States Naval Operations 

in World War II, vol. 4, p. 181.

369 Ibid., pp. 182–83.

370 Ibid.

371 Fuchida and Okumiya, Midway, p. 250.

372 Ministry of Defence (Navy), Defensive Phase,

p. 164.

373 Fuchida and Okumiya, Midway, p. 249.

374 Parshall and Tully, Shattered Sword, p. 385.

375 Ibid., pp. 387–88.
III Japanese A-Go Operation (Battle of the 

Philippine Sea), 13–22 June 1944 

Situation and Theater

The Japanese A-Go operation was activated on 13 June as a reaction to the 

U.S. invasion of the southern Marianas (Operation FORAGER). The entire 

operation lasted about ten days. The Japanese forces consisted of nine 

carriers with 473 aircraft, some 630 land-based naval aircraft, about fifty surface 

combatants, and twenty-two submarines. The U.S. forces that initially took part 

in FORAGER consisted of some 67,500 troops and some 550 ships (not including 

logistical support and underway-replenishment ships).1

 The U.S. forces included 

fifteen large and light carriers, with about 950 aircraft, and seven escort carriers, 

with about 170 aircraft, plus about 180 other surface combatants and twenty-eight 

submarines. In addition, the United States had about 880 aircraft based in the Gilberts and the Marshalls, though relatively few took part in the invasion of Saipan. 

The Japanese were strategically on the defensive, but the A-Go operation itself was a major naval offensive operation, aimed at denying local sea control to 

the enemy. In contrast, the United States was strategically on the offensive, with a 

major amphibious landing under way; the Fifth Fleet conducted a major defensive 

naval operation aimed to maintain local sea control around the southern Marianas. 

The clash between the opposing carrier forces on 19–20 June resulted in a decisive 

victory for the Fifth Fleet. However, the Fifth Fleet’s operational objective was not 

consolidated, because the enemy fleet escaped, if much weakened, to fight another 

day. The planning and execution of the A-Go operation and the battle of the Philippine Sea by the respective sides are rich in lessons that are valid even eighty years 

after the event and will remain so for many years in the future.

Strategic Background 

The United States developed a series of plans from 1924 through 1938 that contemplated an advance across the Central Pacific in case of war with Japan. These plans 

were code-named ORANGE. The planners assumed that it would be essential to establish subsidiary U.S. bases in the Japanese mandated islands for the purpose of 

protecting the line of communications between the Philippines and the continental 

United States. It was generally agreed that bases in the Marshalls and probably in 

the Carolines would have to be seized to facilitate the advance of the U.S. fleet to 
J

the Philippines or to protect its lines of communications in the western Pacific. The 

Marianas played a marginal role in these considerations, because they were north 

of the main strategic axis (direction) from Hawaii to the Philippines. These plans 

were the first rudiments of the wartime Central Pacific strategy.2

All U.S. prewar plans were prepared under the assumption that the United States 

would be engaged in a war with Japan alone. However, with the outbreak of war in 

Europe in September 1939 and gradual strengthening of links with Great Britain, 

this assumption became invalid. It became necessary for the United States to reach 

agreement with its potential allies in anticipation of its actual entry into the war 

against the Axis.3

 Hence, the American, British, and Canadian staff representatives 

met in Washington, D.C., on 29 January 1941 (the ABC-1 conference) to discuss 

possible strategies should the United States become an active participant in a war.4

They agreed that “should the United States be compelled to resort to war” the Atlantic and European area would be considered the “decisive theater,” because Germany was the predominant member of the enemy coalition. This was the genesis 

of the “beat Germany first” concept, which would remain the basic strategy of the 

Western Allies until 8 May 1945.5

In April 1941, the U.S. Joint Board set about bringing its own plans up to date in 

light of these conversations. The resulting new strategic plan, RAINBOW 5, merely 

restated the decision of ABC-1 and assigned more specific tasks to U.S. forces. Germany would be defeated first; the Philippines would be held as long as possible; the 

U.S. fleet would prepare to capture positions in the Marshalls and Carolines.

During the TRIDENT conference, held in Washington, D.C., on 12–27 May 

1943, President Franklin D. Roosevelt (1882–1945) and the British prime minister, 

Winston S. Churchill (1874–1965), and their military advisers discussed the situation in the Mediterranean theater, Burma, and China. They also reaffirmed their 

determination to get on with the war in the Central Pacific. On 14 May 1943, the 

American representatives circulated to the Combined Chiefs of Staff (CCS) a paper, 

drawn up by the various subcommittees of the U.S. Joint Staff, entitled “Strategic 

Plan for the Defeat of Japan.” Actually, the paper was more an estimate than a plan. 

The main strategic principles endorsed by the highest American planners for the 

war in the Pacific in 1943–44 assumed that to bring about the unconditional surrender of Japan it would be necessary to obtain a foothold in China, so as to make best 

use of that country’s enormous manpower and to establish air bases from which to 

conduct the strategic bombing of Japan. China’s mainland could be entered from 

the west, through Burma, or from the south, through the Strait of Malacca, the 

South China Sea, and Hong Kong. Another axis of advance was across the Pacific 

through the Celebes Sea to Hong Kong. The American planners envisaged a twopronged approach to the Celebes Sea and Hong Kong: a westward advance from 

Hawaii through the Central Pacific, and a westward advance from the Solomons 
J()

Archipelago to the Bismarcks, then northward along the eastern coast of New Guinea. 

They selected the advance across the Central Pacific to receive the main effort. 

Adm. Ernest J. King (1878–1956), Chief of Naval Operations (CNO) and Commander in Chief, United States Fleet (COMINCH), was the strongest advocate of 

the drive through the Central Pacific. He was especially keen for the capture of the 

Marianas. King argued that for many years prior to the war students at the Naval 

War College in Newport, Rhode Island, had studied the problem of supporting or 

recovering the Philippines as a prerequisite for defeating Japan. The advance from 

Hawaii to the Philippines via the Central Pacific had been considered the best approach. King firmly believed that the Marianas were the key to the western Pacific. 

Their capture would seriously endanger the Japanese sea lines of communications. 

Moreover, it would most likely bring the Imperial Japanese Navy (IJN) into a decisive battle. The Marianas would also provide bases from which to attack the Japanese home islands. 

In the final session of the TRIDENT conference on 27 May, the CCS did not commit itself specifically to an invasion of the Marianas. However, its members agreed 

to the proposed two-pronged advance across the Pacific. They also agreed that the 

Allied strategic objectives in 1943–44 should be air operations in and out of China; 

ejection of the Japanese from the Aleutians; seizure of the Marshalls and the Carolines; capture of the Solomons, the Bismarck Archipelago, and New Guinea; and 

intensification of operations against enemy lines of communications. 

In July 1943, the Allies modified their plans for the Central Pacific drive, having realized that a direct assault on the Marshalls from Hawaii would require more 

shipping and troops than were available. It might have also required draining forces 

from Gen. Douglas MacArthur’s Southwest Pacific Area (SWPA). Another reason 

was the need to obtain much better aerial photography of the Marshalls before 

invading them; very little was known about the enemy defenses there. Hence, the 

Gilberts were selected as the initial operational objective in the projected Central 

Pacific campaign. This island group would provide air bases for photographic reconnaissance of the Marshalls. The Joint Chiefs directed Adm. Chester W. Nimitz 

(1885–1966), Commander in Chief, Pacific Ocean Areas (CINCPOA) and Commander in Chief, United States Pacific Fleet (CINCPac), on 20 July 1943 to capture 

Tarawa in the Gilberts and Nauru as a preliminary to the invasion of the Marshalls. 

The target date for the invasion of the Gilberts (Operation GALVANIC) was set for 

15 November 1943.

During a conference at Quebec (QUADRANT) on 17–24 August 1943, the Allied 

leaders accepted the revised plan for the Central Pacific. This included capture of 

the Marshalls, Ponape, Woleai, and Truk in the Carolines; development of Truk as 

a major fleet base; and capture of Yap and the Palaus. At Admiral King’s insistence, 

the Marianas were included as a possible alternative to the Palaus or as a concurrent 
J

operation. Nimitz proposed substituting Makin, in the Gilberts, for Nauru, as being 

closer to the Marshalls. That recommendation was accepted—Nimitz was authorized to seize Tarawa, Makin, and Apamama in the Gilberts. On 20 November, the 

Allied forces invaded Tarawa and Makin, and within four days both atolls had been 

captured. Apamama was then occupied.

A new factor that helped King’s case for the invasion of the Marianas was an 

announcement by the Army Air Forces (AAF) that a new very-long-range (5,830 

miles) heavy bomber, the B-29 Superfortress, would soon be introduced. By late 

1943, it had become apparent that the B-29s would not be off production lines in 

sufficient numbers to play an important role in the preinvasion bombardment of 

Europe and that the B-17s and B-24s already there were sufficient for the task. That 

meant they could all be employed against Japan; the question was how best to do 

so. These new heavy bombers could be based in Australia, China, or the Marianas. 

Gen. George Kenney (1889–1977), commander of the Allied Air Forces, SWPA, argued that the new bombers should be assigned as a matter of the priority to his own 

command. However, Gen. Henry H. Arnold (1886–1950), commanding general 

of the AAF, rejected Kenney’s idea, presenting instead an “Air Plan for the Defeat 

of Japan” in which he estimated that by October 1944 ten groups of B-29s, each 

with twenty-eight planes, might be available. Their use would require the capture 

of island positions within 1,500 miles of Honshu. Arnold proposed also to build a 

chain of airfields north and south of Changsha, China, all within the effective B-29 

range from Japanese cities. However, AAF planners were not very happy with basing B-29s in China, partly because of the logistical difficulties and partly because 

they were skeptical of the ability of the Nationalist Chinese to hold the airfields. Accordingly, after the Quebec conference Arnold urged that the Marianas be captured 

and D-day for the operation be advanced to mid-1944.

At the SEXTANT conference, in Cairo on 4–6 December 1943, Roosevelt and 

Churchill approved a new schedule of operations in the Pacific that assigned the 

capture of the Marianas a target date of 1 October 1944. This operation would follow invasions of the Marshalls in January, Ponape in May, and Truk in July. The 

SWPA’s forces were scheduled to seize Kavieng (on New Ireland), Manus (in the 

Admiralties), and Hansa Bay (northeast coast of New Guinea) and then to move 

to the tip of the Vogelkop Peninsula, on New Guinea, in August 1944. The CCS 

too endorsed the Central Pacific route. Its “Overall Plan for the Defeat of Japan” 

stated that the Allies ultimately intended to “obtain objectives from which we can 

conduct intensive air bombardment and establish a sea and air blockade of Japan, 

and from which to invade Japan if this should prove necessary.” This would require 

a single axis of advance across the Central Pacific in time for a major assault in the 

Formosa–Luzon–China area by the spring of 1945. Two axes of advance would be 

mutually supporting, but a drive across the Central Pacific alone promised a faster 
J()

advance toward Japan and its vital lines of communications, an earlier capture of 

strategic air bases close to the Japanese home islands, and of greatest importance, 

greater likelihood of triggering a decisive battle with the enemy fleet.

The preliminary draft of the Central Pacific campaign plan (GRANITE) issued 

by Nimitz on 27 December 1943 envisaged the following sequence of operations in 

1944: invasion of Kwajalein, in the Marshalls, on 31 January; an attack on Kavieng 

and air strikes on Truk on 20 March; and assaults on Eniwetok on 1 May, Mortlock 

(Nomoi Island) on 1 July, Truk on 15 August, and Saipan, Tinian, and Guam on 

15 November. On 13 January 1944 Nimitz issued a revised GRANITE plan. Among 

other things, the captures of Mortlock and Truk were rescheduled for 1 August. 

The possibility was also suggested of bypassing Truk and invading the Palaus on 21 

August, making it possible to invade the Marianas by 1 November. Nimitz’s planners assumed that Palau would be less costly and time-consuming to take than the 

Japanese stronghold Truk.

In the last days of January 1944, SWPA and Pacific Ocean Areas (POA) representatives met at Pearl Harbor to discuss pending operations in both theaters. 

Among the participants were Admiral Nimitz; his chief of staff, Rear Adm. Charles 

H. McMorris; Vice Adm. John H. Towers, Commander, Air Force, Pacific Fleet; 

MacArthur’s chief of staff, Gen. Richard K. Sutherland; General Kenney; and Vice 

Adm. Thomas C. Kinkaid. Nimitz presented a revised GRANITE plan. There were 

almost immediate objections from the SWPA. Sutherland argued for pooling all 

available resources in the Pacific: “If Central Pacific would move against Palau after the Marshalls as the next operation and . . . make available to Southwest Pacific Area, the amphibious force now contemplated for Truk, we can take all New 

Guinea, the Kai and Tanimbars, and Halmahera in time to join you in amphibious movement to Mindanao this year.” Both Kenney and Kinkaid dismissed the 

Marianas as a base for bombing Japan. Even some members of Nimitz’s staff were 

doubtful of their value; Rear Adm. Forrest P. Sherman (1896–1951, CNO from 

1949 to 1951), Nimitz’s deputy chief of staff, believed that the capture of the Marianas would be extremely costly and that ports seized would be of limited usefulness 

to the Pacific Fleet. McMorris doubted that long-range bombing of Japan would in 

any case cause the capitulation of Japan.

Admiral King, hearing about the conversations at Pearl Harbor, was furious. In 

a stern letter to Nimitz he declared that the idea of rolling up the Japanese by advancing along the New Guinea–Halmahera–Philippines axis instead of up the lines 

of communications across the Central Pacific was absurd. He also asserted that 

such ideas were not in accordance with prior decisions of the Joint Chiefs of Staff 

(JCS). King was not the person to stand idly by while theater staffs undermined his 

favorite war plan at the very moment of fruition.
J

On 31 January 1944, Central Pacific forces invaded Kwajalein Atoll. After only 

four days’ fighting all the objectives were secured. Majuro Atoll was occupied without resistance. Nimitz was then able to accelerate his plans for invading the western 

Marshalls. Eniwetok was assaulted on 17 February, two months ahead of schedule; 

it was captured after only six days of fighting.

MacArthur’s plans called for simultaneous seizure of Kavieng and Manus on 

1 April 1944. However, he changed this schedule after Allied aircraft flew over 

the Admiralties on 23 February and found no evidence of Japanese presence. 

MacArthur made a quick decision and sent the 1st Cavalry Division to land on Los 

Negros on 29 February.6

 Allied troops encountered light resistance.7

In February–March 1944, at a planning conference in Washington, D.C., the 

entire schedule of the operations in the Pacific was reconsidered. Most planners 

agreed on the need to capture a lodgment somewhere in the strategic triangle of 

Luzon, Formosa, and the coast of mainland China. The objective was completely 

to cut off lines of communications between Japan and the Netherlands East Indies 

(NEI). Bases for long-range bombers could be established within reach of Japanese 

industrial centers.8

 Admiral Sherman and General Sutherland presented the views 

of their respective commands about the future operations in the Pacific. Sutherland argued that RENO II (an advance across the north coast of New Guinea to 

Mindanao) and GRANITE campaign plans were each relatively weak and would produce only slow progress.9

 Hence, he proposed a combined advance along the general New Guinea–Mindanao axis, bypassing Truk. Combining amphibious forces 

would make it possible to enter Mindanao by 1 December 1944. For such a drive, 

naval forces could be based at Manus. However, MacArthur would require additional forces from Nimitz; in fact, MacArthur hoped that Nimitz would assign him 

Adm. William F. Halsey (1882–1959), Commander, South Pacific Area (SOPAC), 

as Commander, Allied Naval Forces, because of his ability, rank, and prestige. 

MacArthur sent a message on 2 February reinforcing Sutherland’s argument that 

the proposed offensive could bring Allied forces to the Philippines in December 

1944. In his view, advances along two weak axes should not be conducted; they 

would not achieve strategic results for many months.10

MacArthur’s chief opponent in this debate was not Nimitz but Admiral King. 

Halsey’s SOPAC forces operated in their own area, where they were primarily concerned with the potential threat to Allied forces in the southern and southwestern 

Pacific. King could see no sound reason for placing them under MacArthur’s command; MacArthur, King declared, apparently did not accept JCS decisions. King 

believed that it was not a propitious time to change strategy in the Pacific.11 He 

insisted that the Carolines and Marianas had to be captured to eliminate the enemy 

threat from the flanks to the Allied offensive in the southwestern Pacific.12
J()

Gen. George Marshall (1889–1959), Chief of the Staff of the Army, suggested that the JCS issue a new directive to both Pacific commands, after the Joint 

Strategic Survey Committee (JSSC) had been directed to study the matter anew. 

Among other things, the new study should clarify which geographic objectives 

should be captured and their sequence—that is, which axis of advance offered the 

best chance for victory in the Pacific. The JSSC came out clearly in favor of King’s 

and Nimitz’s strategic plan—to the disappointment, not surprisingly, of MacArthur 

and his staff. The JSSC recommended that the JCS resolve the present conflict between the SWPA and POA campaign plans by directing that the primary effort 

against Japan be made through the Central Pacific and that the SWPA cooperate in 

and support that effort.13

General Marshall was also not completely satisfied with the JSSC’s study, feeling 

that it did not adequately address the allocation of resources or the employment of 

the great Allied superiority in the air. Hence, he directed other committees to study 

the matter further. King agreed that these studies could be beneficial, but he was 

concerned that they would further delay GRANITE. On 5 March MacArthur proposed that the Hansa Bay operation scheduled for 22 April be omitted and that he 

move instead to Hollandia, some three hundred miles farther up the coast of New 

Guinea. He suggested employing for that purpose POA’s fast carriers and shipping 

tentatively earmarked for the Kavieng-Manus operation. These suggestions were 

in line with MacArthur’s RENO II plan, which reached Washington, D.C., within a 

few days.

Nimitz, who was summoned to Washington, argued that if MacArthur’s plan 

were accepted, it would slow down POA operations. He contended to the JCS that 

MacArthur should not retain POA forces after the capture of Kavieng and Manus, 

because that would delay the movement into the Marianas until the approach of 

the typhoon season. The Japanese would gain additional time to strengthen their 

defenses in the Carolines and Marianas, and the Allied plan to reach the Luzon–

Formosa–China area in early 1945 would be endangered. 

Nimitz suggested two alternative schedules for the remainder of 1944. The first 

contemplated invasion of Truk on 15 June, the southern Marianas on 1 September, 

and the Palaus on 15 November. The second alternative schedule envisaged bypassing Truk and going into the southern Marianas on 15 June, Woleai on 15 July, Yap 

on 1 September, and the Palaus on 1 November. On reconsideration, Nimitz decided that if the second schedule were accepted the capture of Yap could be deferred 

until the Palaus had been taken and that a fleet anchorage could be established at 

Ulithi. This in turn would advance the target date for the Palaus to 1 October.

In the end, the JCS accepted neither Nimitz’s nor MacArthur’s schedule of operations in toto. Neither did it accept without changes the conclusion of the JSSC that 
J

a fundamental strategic prerequisite of the seizure of objectives in the Formosa–

Luzon–China coast zone was control of the Marianas, Carolines, and Palaus. At the 

insistence of General Marshall, Mindanao was added as one of the intermediate objectives that the Allied forces had to seize before proceeding with operations in the 

Philippines. The JCS directive issued to MacArthur and Nimitz on 12 March was 

a compromise between the SWPA and POA plans. It stated that the most feasible 

approach to the Formosa–Luzon–China area was via occupation of the Marianas–

Carolines–Palau–Mindanao zone.

The final schedule of the Pacific operations canceled the Kavieng operation 

and called for the complete isolation of the Rabaul-Kavieng area with the minimal 

forces; early capture of Manus and its development as an air and fleet base; occupation of Hollandia by SWPA forces (15 April 1944); establishment of control in the 

Marianas–Carolines–Palau area by POA forces by neutralizing Truk and occupying the southern Marianas (15 June); seizure of the Palaus (15 September); capture 

of Mindanao by SWPA forces supported by the Pacific Fleet (15 November); and 

occupation of Formosa (15 February 1945) or, if necessary, Luzon (15 February 

1945). The objective in occupying the southern Marianas was “to secure control of 

sea communications through the Central Pacific by isolating and neutralizing the 

Carolines and by the establishment of sea and air bases for operations against Japanese sea routes and long range air attacks against the Japanese home land.”

By May 1944, SWPA forces had captured the Admiralties, the Saint Matthias 

islands, New Britain, and Hollandia, on Dutch New Guinea. The Japanese now 

controlled only the area west of a line from Timoeka Island to Wakde, with the 

exception of isolated garrisons at Wewak and Hansa Bay. The Japanese defensive 

perimeter in the Pacific, however, still stretched from the Kurils in the north to 

enclose the Marianas, the western Carolines, western New Guinea, all of the NEI, 

Malaya, Burma, and the Philippines, as well as isolated strongholds in the Bismarck 

Archipelago, the Marshalls, and eastern New Guinea. 

On 15 June 1944 the U.S. forces launched a major joint operation to seize the 

Marianas (Operation FORAGER), invading the island of Saipan, the first of the three 

objectives in the group. Saipan had to be captured first because from it artillery 

could support an attack on Tinian, which in turn offered the best terrain for bomber bases. Guam was more important politically than militarily, as a former American territory.14 Saipan was secured after twenty-four days of heavy fighting. On 

1 August, the U.S. forces invaded Tinian and later in the same month recaptured 

Guam.15 

The Theater 

The Central Pacific encompasses a very large number of islands and archipelagoes. 

Militarily, in 1944 the most important groups were the Gilberts/Ellices, the Marshalls, the Marianas, the Bonins, and the Carolines. 
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The Gilberts/Ellice archipelago forms a long chain of small, scattered atolls and 

islands. There are sixteen atolls of some significance, totaling 166 square miles of 

land, plus nine atolls, in the Ellices, with nine or ten square miles. Most of these 

atolls rise no more than twelve feet above sea level. They consist of hard sand on 

a coral rock base and minilam soil. The vegetation is coconut palms and underbrush.16 The wet season is from October through March, when westerly winds prevail. Northeasterly trade winds dominate from March to October, during which 

there is very little rain. April is the driest month; from June to November the southwest monsoon brings five to fifteen inches of rain a month. Annual rainfall is between 150 and 180 inches. Temperatures vary from lows of sixty degrees Fahrenheit at night to ninety during the day. Humidity can be high.17

Prior to 1941, the Japanese controlled most of the Micronesian islands, specifically the Marshalls, the Marianas, and the Carolines. These island groups, once 

German possessions, had been taken during World War I by a Japanese expeditionary force, in October 1914. In December 1920 Japan had been granted a Class C 

mandate by the League of Nations to govern them, effective 1 April 1922. These 

territories became known as the Japanese Mandated Territory, or simply the Mandates. The Japanese undertook a vigorous settlement and economic development 

effort in the islands; by the later 1930s, Japanese settlers outnumbered the native 

islanders (in 1940 the total population would be about 131,200). In 1935, after serving the required two-year notice, Japan withdrew from the League of Nations and 

the Mandates become a “closed territory,” and Westerners were restricted from entry.18 Meanwhile, the island of Guam, part of the Marianas Archipelago, and Wake 

Island were administered by the United States, and the Gilberts (Kiribati today) 

remained under British control. 

The Mandates extended for about 2,500 miles in the east–west direction (see 

map 11). They encompassed about 1,460 islands and reefs, with 860 square miles 

of land. The larger islands are of volcanic origin. In mid-1944, most of these islands 

were heavily populated. The smaller islands, especially the Marshalls and Carolines, are coral atolls, most of which were uninhabited.19

The Marshalls consist of a double chain of coral atolls: the Radak (Sunrise) 

chain to the east, the Ralik (Sunset) to the west. These chains are separated by 

about a hundred miles of ocean. They encompass thirty-two islands and 867 reefs, 

about sixty-six square miles in land area. None rises more than a few feet above sea 

level. The main island in the Marshalls is Jaluit, in the Ralik group.20 Jaluit is some 

245 miles from Kwajalein and 110 miles southwest of Majuro Atoll. Jaluit’s lagoon, 

some thirty miles long and twelve miles wide, containing about fifty islands, has 

three deep passages and an anchorage twenty-five to thirty fathoms deep.21 Majuro 

is about five miles long and one mile wide; its anchorage is largely protected from 

bad weather, though occasional northerly and westerly winds cause rough seas.22
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20o 10o 140o 150o 160o 140o 150o 160o 170o 170o

E

20o N

10o

Map 1: JA

PANESE 

MAN

D

ATED IS

LANDS

Academics/jmo/2013/vego/JMI

Wake

Island

Saipan

Rota

Guam

Truk

Kapingamarangi

Bikini

Tarawa

ISLANDS

GILBERT

Majuro

MARIANAS

ISLANDS

Farallon de Pajaros

Maug Island

Asuncion

Agrihan

Pagan

Alamagan Guguan

Sariguan Anatahan Farallon de 

Medinilla

Tinian

C

A

R O L I NE I S L A

N

D S

Kavieng Rabaul

Palau

Angaur

PuloAnna

Tobi

Helen Reef

Sonsorol

Merir

Yap

Ulithi

Fais

Ngulu

Sorol

Eauripik

Woleai

Faraulep

Gaferut

Olimarao

Lamotrek

Lfalik

Ela ot

Satawal

Namonui

ot

Nomwin

Puluwat Pulusuk Namoluk

Satawan

Pulap

Murilo

Minto Oroluk

Losap

Ngatik

Nukuoro

Pakin

Ponape

Mokil

Pingelap

Kusaie

Eni

wertok

Ujelang

M A R S H A L L I S L A N D

R

S

ongelap

Rongerik

Ebon

Namorik

Ailinglapalap

Namu

Lae

Wotho

Ujae

Ailinginae

Pokaakku

Bikar

Utirik

Ailuk

Likiep Kwajalein

Mejit

Wotje

Maloelap

Arno

Mille

Jaluit

Jabwot

Erikub

Map 11 

Japanese mandated islands
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The centrally located Kwajalein Atoll extends for about sixty-six miles and is almost eighteen miles wide. Kwajalein encloses 325 square miles of water, with about 

ninety-seven small islands on the surrounding reef. The principal island is Roi. 

In the northern and southern parts of the lagoon the water is between fifteen and 

twenty fathoms deep. The tidal range is about three feet, and the current is two 

knots at the atoll’s entrances, of which the best for larger ships is South Pass.23 Mille 

Atoll, with thirty islands, sixty miles southeast of Majuro, is about twenty miles 

long and ten wide. The sixty-four-island Maloelap group is about thirty miles long 

and between eight and fifteen wide.24

The circular Eniwetok Atoll consists of about thirty low-lying islands, with two 

good entrances to its lagoon—South Channel and East Channel—as well as a shallow entrance in the southwest. The anchorage is exposed to the wind in all directions. Most of the islands are on the eastern side of atoll and have sandy beaches.25

From November to April the prevailing winds in the Marshalls are northeast 

trades. From May to October easterly and southeasterly winds dominate, with frequent calms. Gales seldom occur, though squalls may be expected in June and July. 

The rains fall every month in the year; annual rainfall is about eighty inches. The 

wettest months are May and June, the driest January and February. The annual 

mean temperature is eighty-two degrees Fahrenheit. Fog is very rare.26

Wake Island consists of the island of Wake and two islets—Wilkes and Peale. 

With a surface area of about 1,800 acres, Wake is the largest island in the group. The 

central lagoon is surrounded by a reef. The atoll has a tropical climate, with temperate storms during the winter months and surface temperatures of about eighty 

degrees Fahrenheit in summer and autumn.

The Marianas were the smallest of the Japanese mandated islands. The 425-milelong chain of hilly and volcanic islands runs north–south in a shallow curve. The 

northernmost islands are volcanic peaks, rising six to twelve thousand feet above 

the sea bottom. The southern islands are more important militarily and economically.27 The largest island in the archipelago is Guam (215 square miles), followed 

by Saipan (forty-seven square miles), Tinian (forty square miles), and Rota (thirtytwo square miles). Guam is thirty-two miles long and ten wide;28 Saipan is about 

a hundred miles northeast. Tinian, separated from Saipan by a three-mile-wide 

channel with a swift northeastward current, extends for ten miles and is some five 

miles wide.29

In the Marianas, climate is dominated by tropical maritime air. In the summer, 

equatorial air masses bring increasing temperatures and humidity. In the winter, 

continental air masses occasionally move out over the islands from Asia. The Marianas are affected by the warm Kuroshio Current; the average temperature is about 

eighty-one degrees Fahrenheit. Prevailing winds are easterly.30 The Marianas are 

also affected by southwest monsoons in August and September, bringing strong 
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winds and heavy precipitation. During June, three or four weak fronts pass from 

the northwest, bringing a thin sheet of upper clouds and an increase in lower cloud 

cover to five-tenths or six-tenths, though with little or no precipitation. Normally 

one typhoon per year can be expected, usually in September or October.31

In the Marianas, it is generally more cloudy over land areas than over the surrounding ocean. Cloud cover averages over five-tenths during the dry months and 

eight-tenths during the wet months. The dry season (November to June) is characterized by scattered cumulus clouds between 1,500 and seven thousand feet. During frontal passages, high clouds and lower cumulonimbus, between five hundred 

feet and fifteen thousand, are present. During the wet season (July to November) 

cumulonimbus clouds are invariably present, with bases around 1,500 feet and tops 

varying between seven and twenty-five thousand feet. These clouds generate intermittent heavy showers. A rapid shift from the dry to the rainy season starts about 

1 July. From December to June, rain falls from cumulus or stratocumulus clouds 

associated with weak fronts moving from the northwest. During the rainy season 

the towering cumulonimbus clouds can be as high as twenty-five thousand feet.32

The Nanpō Shotō is a collective term for the group of islands extending south 

of the Japanese home islands for some 750 miles. They encompass the Izu Islands 

(Izu Shotō), Bonin Islands (Ogasawara-guntō), Volcano Islands (Kazan Rettō), 

Nishinoshima (Rosario Island), Okinotorishima (Parece Vela), and Minami-ToriShima (Marcus Island). The Bonins comprise three smaller groups (Muko Jima, 

Chichi Jima, and Haha Jima), with about thirty subtropical and tropical islands.33

The weather in June is generally favorable: cloudiness is five-tenths on average, and 

rain can be expected on about three days, during light frontal passages, and one 

day of fog.34

The Volcano group consists of three islands: Iwo Jima, Kita Iwo Jima, and Minami Iwo. Iwo Jima extends four miles from northeast to southwest and is about 

2.5 miles wide. Marcus Island, only about four miles long, has no good anchorage; 

heavy surf makes landing difficult.35

The Carolines (also called the New Philippines) stretch from longitude 130° to 

163° east, about 1,700 miles. In the north–south direction they extend from 10°

north to the equator. Most of the islands are north of 5° north; the northernmost 

atoll is Ulithi. The Carolines are a vast chain, with 936 coral and volcanic islands, 

enclosing about 1.3 million square miles. However, their land area is only around 

830 square miles.36 The Carolines are geographically divided into western and eastern groups. The islands range from fairly large ones, with mountains and streams, 

to tiny, palm-clad islets and coral reefs rising only a few feet from sea level.37 The 

largest islands in the eastern Carolines are Truk (Chuuk today), Ponape (now 

Pohnpei), and Kusaie (Kosrae today). The thirty-mile-long, triangular Truk Atoll 

occupies a central location and consists of about seventy islands/islets. Most are on 
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the reef ’s rim, 150 miles in circumference, but eleven islands and about twenty islets are scattered within the eight-hundred-square-mile lagoon. There are five main 

entrances into the lagoon.38 The principal one, the Northeast Pass, is three-quarters 

of a mile wide and twenty fathoms deep; a reef in the middle narrows it to 750 

yards and reduces its depth to between four and a half and five and three-quarters 

fathoms. Truk Harbor is between the southern side of Dublon Island and Eten Islet; 

its depth varies from one to twenty fathoms. Tides are two to three feet high. The 

bottom is composed of sand, coral, and mud. Currents inside the lagoon are weak. 

There are six other atolls within two hundred miles of Truk.39

The island of Ponape, about 375 miles east of Truk, is the largest of the Caroline 

Islands. Its mountains rise to 2,500 feet. Ponape is covered with forests and has 

many streams. Ponape Harbor is well protected from ocean swells by a barrier reef, 

but its usable area is only five square miles. Hatalinin Harbor, on the east side of 

the island, is a suitable anchorage for only a few ships, having an area of one square 

mile, with depths from five to fifty fathoms. Ronkite Harbor, on the southwestern 

side of the island, has water area of only half a square mile. The lagoon waters on 

the western side of the island, though greatly broken up by coral patches, have a 

usable anchorage of fifteen square miles between Ronkite and Ponape. All three 

ports can be entered through Tauak, Palikir, and Jokaj Passages, varying in width 

between 450 and 150 yards. Ponape has the greatest natural defensive strength, 

with rugged terrain and barrier and fringing reefs offering few openings.40

Some three hundred miles southeast of Ponape is the island of Kusaie. This 

forty-two-square-mile island is surrounded by coral reefs. It has steep mountains 

and dense vegetation. There are also about a dozen nearby islands. 

The western Carolines comprise the Palau and Yap groups.41 The Palau group 

is the westernmost part of the Carolines. It consists of about a hundred islands 

and islets, encompassing some 185 square miles. All are irregularly shaped and 

mountainous-volcanic in origin.42 Palau is twenty miles long by five wide. Another 

large island is Angaur. Both of these islands have enormous phosphate deposits. 

The town of Koror is located on an island off the southern end of Palau Island.43

The Yap group consists of four large islands encompassing some eighty square 

miles. The islands are enclosed by broad fringing coral reefs in some places more 

than a mile wide, separated from each other by very narrow channels. All the islands have low hills, with rounded summits and gentle slopes. Streams are intermittent, and lowlands are generally narrow.44 The terrain of Yap island proper, however, is mountainous and broken, covered with forests of coconut and areca palms, 

bamboo, and crotons.45 The principal harbor is Tonil, on the eastern side of Yap, 

with an entrance only a hundred yards wide, a small anchorage (six-tenths of a 

square mile), and depths of between twelve and twenty fathoms. Spring tides are 

about four feet.46
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The climate in the Carolines is dominated by the northeast trade winds. The 

exception is the area west of 145° east longitude, where the effect of the Asiatic 

monsoons is felt during the summer months. The best weather conditions in the 

Carolines are from April to the end of November, when westerly winds prevail, particularly in August and September.47 Typhoons can occur in any month, but they 

are most common from July through November, with the highest frequency in September. Daytime temperatures vary from eighty-three to eighty-nine degrees Fahrenheit, nighttime between seventy-four and seventy-seven.48 The annual rainfall is 

177 inches. July is the driest month, with only fourteen inches of rain.49 Cloudiness 

is fairly high, with about eight-tenths coverage any month in the year.50

Theater Geometry

The planning and execution of combat employment of naval forces and aircraft 

are greatly affected by geography: position and relative position, the length and 

indentation of coasts, the presence or absence of offshore islands or archipelagoes, 

and distances to be transited. These purely geographic features of a maritime theater largely determine which physical objectives are to be captured, defended, or 

controlled, the length and shape of potential basing areas, the number and size of 

naval and air bases and anchorages, and the length and directional orientation of 

lines of operation and of communications. These natural and human-made factors 

are arbitrarily referred to as “theater geometry.”

Distances from the Marianas to other points in the Pacific are quite large. For 

example, the distances from Saipan to Kwajalein and to Manila are 1,355 and 1,640 

miles, respectively. Guadalcanal, Palau, and Rabaul are 720, 840, and 1,230 miles 

from Saipan. The distance from Saipan to Manila is 1,640, and to Pearl Harbor 

about 3,400. From Saipan to Midway is about 2,210 miles and to Tokyo approximately 1,260 miles.51 Tarawa, in the Gilberts, is separated by about 1,800 miles of 

water from Saipan. 

Kwajalein is some 2,400 miles southwest of Hawaii. The distance from Truk to 

the Palaus is 1,035 miles and to Guam and Kwajalein, 555 and 925 miles, respectively. Yap is about 730 miles from Truk, and Pearl Harbor is about 3,945 miles 

from Palau.52 From Palau it is about six hundred miles due south to the western tip 

of New Guinea, while Mindanao is about six hundred miles due west.

In June 1944, the Japanese still controlled certain atolls in the Marshalls—Mille, 

Maloelap, Rongelap, and Wotje. Mille Atoll had one X-shaped airfield and two 

emergency seaplane anchorages. It was the only airfield within the fighter range of 

the Gilbert Islands. The best anchorage in the Maloelap Atoll is in its western part.53

Rongelap was used by the Japanese as submarine and emergency seaplane bases.54

The Japanese used Wotje Atoll and its seaplane base.55 They had a seaplane base on 

Jaluit and one on Ekidj Island, as well as an airfield on Enybor.56
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In the Marianas, the Japanese used two airfields on Guam, one on Rota, four on 

Tinian, three on Saipan, and one on Pagan. U.S. intelligence believed that airfield 

on Pagan was only for staging purposes.57

The Japanese built one airfield on Iwo Jima and one on Chichi Jima.58 These 

were important staging points between the home islands and Micronesia.59 The 

Japanese also had an airfield on Marcus Island.60

In the Carolines, the Japanese used Truk as an advanced submarine base. Truk 

also had an airfield and two seaplane bases.61 On Ponape, the Japanese operated a 

seaplane base on the northeast shore of Langar Island, as well as several seaplane 

anchorages. Kusaie accommodated about a dozen vessels and a seaplane base.62

Satawan, Puluwat, Woleai, Palau, and Yap each had a Japanese airfield. By late April 

1944 two additional fields were under construction on Palau. The airfield on Yap 

was operational but without aircraft. Palau was also used as a submarine base. Japanese submarines sporadically stopped at Saipan en route to and from the home 

waters.63

The IJN used Brunei Bay and the area of Singapore and Lingga (off the eastern 

coast of Sumatra) as bases for its surface forces. These bases were beyond the effective range of the Allied land-based aircraft on Morotai. However, they were within 

the range of B-29s based in the China-India-Burma theater. The main shipping 

routes to and from Singapore passed east of the Lingga Archipelago. 

The largest islands in the Lingga Archipelago are Singkep and Lingga. Singkep, 

twenty miles long and twenty wide, rises to some 1,600 feet in its eastern part; the 

remainder is low and marshy. Lingga extends for about thirty-five miles. The eastern part of the island is mostly low lying, while its western part is mountainous, rising to about 3,800 feet. Other islands in the archipelago are hilly, but elevation does 

not exceed five hundred feet. The coasts of the Lingga Archipelago are all highly indented; there are many shallow bays bordered by rocky headlands, and the seaward 

approaches are made difficult by extensive shoals and coral reefs.64 Brunei Bay, on 

the northwest coast of British Borneo, occupied an excellent position for operations 

in the South China Sea. The 330-square-mile bay has water depths varying from 

five to twenty fathoms and could accommodate a large number of ships of all sizes.65

On Mindanao, the only anchorages of importance are at Masinloc, Dumanquilas Bay, Davao Gulf, and Sarangani Bay. Masinloc is about eight miles long and over 

half a mile wide at its narrowest point, but it is completely sheltered from wind or 

sea. Dumanquilas, twenty-five square miles, has depths from two to about twenty 

fathoms; its anchorage is about eleven miles wide at its entrance and can accommodate hundreds of vessels of all types. It could be easily mined but is protected from 

all winds and has good holding ground. It was considered by the Japanese the best 

place available south of Manila for a temporary fleet base.66 Sarangani Bay’s anchorage is poor, because of its great depths. Davao Gulf also is too deep for anchoring 
J

(from twelve to twenty fathoms), except close inshore, greatly limiting the number of ships that can be accommodated. Additional anchorage space is available at 

Malipano, about seven miles southeast.67

In 1944, the Japanese had thirty-two airfields and strips on Mindanao. Allied 

intelligence estimated that at least six airfields, with a total capacity of five hundred 

aircraft, were within a fifty-mile radius of Davao, on the southern coast. In the Del 

Monte area, on Mindanao’s northwest coast, was a smaller group of fields, with a total capacity of more than 150 aircraft. Other fields were located on the Zamboanga 

Peninsula. A single field in the vicinity of the Surigao Peninsula in the northeast 

could support fifty to a hundred aircraft.68

The Japanese used a new fleet anchorage at Tawi-Tawi, in the Sulu Archipelago. 

The Tawi-Tawi Group is the third largest in the archipelago;69 it is at the southwestern end of the Philippines. Tawi-Tawi holds a commanding position in relation to 

the Makassar Strait and the Molucca Passage. This ten-by-thirty-mile island has a 

highest elevation of about 1,800 feet. Its anchorage encompasses fifty-three square 

miles, with depths varying from five to twenty fathoms; it is nearly five miles in diameter and is surrounded by extensive coral reefs. Mining of its two closely spaced 

entrances was difficult in 1944 because of the deep water.70 Tawi-Tawi was poorly 

protected against attack by submarines. It also lacked an airfield to train carrier air 

crews.71

By May 1944, the United States built several advanced bases in the Gilberts and 

the Marshalls. On the island of Betio the existing Japanese airstrip was reconstructed and used for B-24 medium bombers. A fighter airstrip was built on Apamama 

Island. A naval base and air facility was formally established on Majuro Atoll on 4 

May. Majuro’s large and deep anchorage was capable of accommodating the largest 

surface combatants, including aircraft carriers, but Majuro had no shore installations or medical facilities. The fleet’s needs were met by repair ships, submarine 

and destroyer tenders, tankers, and supply ships. Majuro’s air facilities were capable 

of supporting two Marine dive-bomber squadrons and half a patrol squadron and 

temporarily staging one Army fighter group.72 In mid-March 1944, 4th Marine Air 

Wing headquarters, with Marine Air Group 13, was established on Majuro.73 An 

advanced air base and minor fleet facilities were established on Kwajalein Atoll. On 

Kwajalein was built an airstrip; a seaplane base already existed on Ebeye. After the 

capture of the archipelago in January 1944, the United States reconstructed three 

Japanese airstrips on Roi and Namur.74 A seaplane base was built on Parry Island, 

in Eniwetok (Enewetak today) Atoll. A large airfield was built on Engebi (Enjebi 

today), in Eniwetok Atoll, to accommodate four Marine air squadrons.75

Allied Command Organization

The Pacific was designated as the U.S. strategic responsibility by a directive of the 

CCS on 30 March 1942. The entire Pacific was divided six days later into three 
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large areas: POA, SWPA, and the Southeast Pacific Area. (The latter never became 

a theater of operation and became essentially irrelevant.)76 This decision was formally approved by President Roosevelt on 30 March 1942. The POA was formally 

established on 8 May 1942. In modern terms a “theater-strategic command,” it encompassed a major part of the Pacific Ocean, excluding the Philippines, the NEI, 

Australia and New Zealand, and New Guinea. Admiral Nimitz was appointed as 

CINCPOA; he was also, as noted above, CINCPac. As CINCPOA, Nimitz was subordinate to the JCS in Washington, D.C. As CINCPac he was directly subordinate 

to Admiral King, CNO/COMINCH. As CINCPac, Nimitz was responsible for administration as well as operations. 

The same JCS directive divided the POA into three “Pacific Areas” (or “maritime theaters of operations,” in modern terms): Northern (NORPAC), Central (CENTPAC), and Southern (SOPAC). Nimitz appointed commanders for 

NORPAC and SOPAC but initially retained control of CENTPAC, including the 

Hawaiian Department. In mid-1943, Nimitz transferred command of CENTPAC to Vice Adm. Raymond A. Spruance (he was promoted to a full admiral on 

4 February 1944).

CENTPAC extended roughly from 42° north latitude to the equator.77 Its 

southern boundary started at the equator at 110° west, ran north to 11°, then angled to the Mexico/Guatemala border. In the other direction, at longitude 130°

east, just off the northwest end of Dutch New Guinea the boundary made a ninetydegree turn to 20° north, where it turned back to the west and south of Formosa.78 

This boundary was moved to 18° 30ʹ north in June 1944.

On 15 February 1944, Nimitz directed the establishment of Forward Area, 

Central Pacific. Its forward boundaries were the positions held by the Japanese, its 

rearward limits the forward edge of the administrative subareas, including the Hawaiian Department and Hawaiian Sea Frontier. Initially the forward area included 

the Ellice, Gilbert, and Marshall Islands. Vice Adm. John H. Hoover, commander 

of Air, Central Pacific, was also designated Commander, Forward Area, Central 

Pacific. He exercised command over all shore-based air forces, island commands, 

and surface forces specifically assigned. He was subordinate to CINCPOA, except 

when other command arrangements were prescribed.79 Major elements of Forward 

Area, Central Pacific were the Air Defense Command; Bomber Command; Search, 

Reconnaissance, and Photographic Command; Dive Bomber and Fighter Command; and Transport Air Corps.80

The Marshall Islands Subarea was established by Nimitz on 4 April 1944. It encompassed all the Marshalls and adjacent seas extending fifty miles out. Its commander 

was subordinate to the forward-area commander for the local defense, administration, and supply of the subarea. It was planned that at some future date, Commander, 

Marshall Islands Subarea would become directly subordinate to CINCPOA.81
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Directly subordinate to Nimitz were all seagoing forces, specifically the Fifth 

Fleet (as the Central Pacific Force had been redesignated on 26 April 1944), under 

Admiral Spruance; Submarine Force, Pacific Fleet (Task Force [TF] 17), under Vice 

Adm. Charles A. Lockwood; and Service Forces Pacific Fleet, under Vice Adm. 

William L. Calhoun. Directly subordinate to Spruance were the Joint Expeditionary Forces (TF 51), under Vice Adm. R. K. Turner; Fast Carrier Forces (TF 58), 

under Vice Adm. Marc A. Mitscher; and Forward Area, Central Pacific (TF 57), 

under Vice Adm. John H. Hoover.82

Nimitz also controlled all ground and tactical air forces of the U.S. Army and 

Marine Corps in the POA. Gen. Robert C. Richardson commanded U.S. Army 

Forces, Central Pacific (changed to U.S. Army Forces, Pacific Ocean Area in June 

1944). In 1944–45, the Army forces deployed in POA consisted of five infantry 

divisions, the 7th, 27th, 77th, 81st, and 96th. Fleet Marine Forces, Pacific, under 

Gen. Holland M. Smith, consisted of six Marine divisions—the 1st, 2nd, 3rd, 4th, 

5th, and 6th. In the POA were deployed the Seventh, Thirteenth, and Twentieth 

Air Forces. The latter, established on 4 April 1944, was a strategic force, directly 

subordinate to General Arnold in Washington, D.C. 

Japanese Command Organization

In contrast to the Allies, the Japanese never had a smooth and working relationship between the top political and military leaderships. The influence of the 

military, and especially senior army leaders, was overwhelming. All major policy and strategy decisions were essentially made at Imperial General Headquarters (IGHQ), with little or no input from civilian leaders or other government 

officials.

Emperor Hirohito was the titular head of the Japanese army and navy. The ministers of war and the navy reported directly to him. Both ministers were formally 

subordinate to the prime minister, but in practice they were largely independent of 

the rest of the cabinet. The highest body advising the emperor on important military matters was the Supreme Military Council, composed of selected generals and 

flag officers. There existed also a Board of Marshals and Admirals, which included 

all fleet admirals and field marshals, but it had little influence on matters that really 

counted.83

IGHQ was also the highest body concerned with operational matters. When it 

was established in November 1937, the navy had misgivings but in fact retained a 

large degree of autonomy, almost equal to that of the army. IGHQ had much less 

authority over the services than the JCS or the British Chiefs of Staff. There was 

no overall chief of staff; thus, no one had the authority to reconcile differences 

between the army and navy. Also, there were no joint army-navy departments or 

bureaus, no joint arena for debating issues of national strategy and drawing up 

strategic and operational plans. 
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Nevertheless, a certain degree of cooperation between the army and navy staffs 

was achieved where otherwise none would have existed.84 IGHQ contained army 

and navy sections, each headed by a chief of staff. The army section, or Army General Staff (AGS), controlled all army forces, including army air force. Its control 

was exercised directly, as in the case of the Air General Army, or indirectly through 

area commanders outside the home islands. The navy section, or the Naval General 

Staff (NGS), was the main operational planning organ of the Japanese navy. As was 

the case in the AGS, many NGS officers held similar billets in the Navy Ministry.

IGHQ acted by the authority of the emperor. At joint meetings, held usually 

twice a week on the Imperial Palace grounds, the two chiefs of the general staffs presided. The emperor occasionally attended these meetings, but rarely those headed 

by the individual service chiefs. The real authority was in the hands of the chiefs 

of staff. Both were solely responsible for strategy, planning, and operations of their 

respective services. The decisions of IGHQ had to be unanimous; otherwise, no action could be taken. If there were disagreement on some important question—for 

example, starting or ending the war—the emperor would resolve the deadlock. The 

prime minister and cabinet were not involved in these matters.85

In theory, the Japanese field commanders were directly responsible to the emperor. In practice they were subordinate to IGHQ; there were no direct communications between the throne and field commanders. Moreover, the Japanese never 

established anything resembling joint or geographically based theater commands. 

Normally, the forces of each service in an area were placed under separate army or 

fleet headquarters, whose commanders received orders through separate channels.86

Cooperation between the navy and the army was in general bad, especially with regard to air support—better at the highest level, worse at intermediate and lower levels. 

Another problem was personal friction between naval commanders and their army 

counterparts.87

All army field forces were directly subordinate through the operational chain of 

command to the AGS. The Japanese army command structure was rather inflexible. A commander had to follow strictly the chain of command and could not 

directly approach other commanders.88

Japanese naval organization was quite different from the U.S. Navy’s. Generally, an administrative command was called a “fleet,” while a major tactical command was a “force.” The navy grouped most of its combat forces into the Combined 

Fleet, responsible for all naval operations in the Pacific theater.89 The Combined 

Fleet was headed by Adm. Soemu Toyoda, who took that post in May 1944 after 

the death of Adm. Mineichi Koga (b. 1885) in March 1944. The Combined Fleet’s 

responsibilities were roughly comparable to those of the U.S. Pacific Fleet. In functional terms, it was composed of “mobile forces” and “area forces.” The former were 

capable of operating in any ocean or sea area. Area forces were normally tasked 
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with the defense of particular geographic regions. They were unable to take strong 

offensive action without assistance from mobile forces. In addition were naval air 

fleets, consisting of naval land-based units and carrier air groups (but only when 

operating from land bases).

In June 1944, directly subordinate to the Commander in Chief (CINC), Combined Fleet were the First Mobile Force, the Central Pacific Area Fleet, the Advance 

Expeditionary Force (Submarines) (or Sixth Fleet), and the Base Air Force (naval 

land-based aircraft). Not all naval forces were part of the Combined Fleet. The 

China Area Fleet, naval district and guard forces, and surface escort forces were 

under the control of the NGS.90

The Combined Fleet underwent a major reorganization in early 1944. The First 

Fleet was disbanded effective 25 February, and the First Mobile Fleet (also called in 

dispatches the First Striking Fleet) was organized from the First and Second Fleets 

and assigned to the Combined Fleet effective 1 March. This resulted in combining 

the six battleships (BBs) of the old First Fleet with the six heavy cruisers (CAs) and 

screening units of the old Second Fleet, thus dividing the striking power of the IJN 

into two fleets—the First Mobile Fleet and the Third Fleet.91

On 10 March 1944, a new headquarters was placed between the Combined Fleet 

and the Fourth Fleet by the establishment of the Central Pacific Area Fleet, under 

Vice Adm. Chūichi Nagumo (see map 12). By 4 April the majority of what had 

been the Eleventh Air Fleet had been reorganized and renamed the Fourteenth 

Air Fleet.92 The major elements of the Central Pacific Area Fleet were the First Air 

Fleet, under Vice Adm. Kakuji Kakuta, at Tinian, and the Fourth Fleet, under Vice 

Adm. Chūichi Hara, at Truk. The First Air Fleet consisted, in turn, of the 61st Air 

Flotilla, on Peleliu, and the 22nd Air Flotilla, at Harushima, in the Truk group.93 It 

also included, after 5 May, the 22nd, 23rd, and 26th Air Flotillas. Also subordinate 

to the Central Pacific Area Fleet were land-based aircraft: the Fifth Base Air Force 

at Saipan (Rear Adm. Takahisa Tsujimura), the 30th Base Air Force on Palau, and 

seaplane base on Chichi Jima.94

For the first two years of the war, the Fourth Fleet controlled all the Japanese 

garrisons in the Mandates and was directly subordinate to the Combined Fleet. By 

March 1944 the Fourth Fleet was limited to Truk, the eastern Carolines, and the 

remaining garrisons in the Marshalls.95 The Fourth Fleet consisted of the 4th Base 

Air Force, at Truk (Rear Adm. Masami Kobayashi), and the 62nd, 63rd, 64th, and 

66th Guard Forces, on Jaluit, Maloelap, Wotje, and Mille in the Marshalls.96 Until 

the U.S. invasion of Truk, the 31st Army there was responsible for all the army 

forces in the Marianas. Its headquarters was later moved to Palau.97

Admiral Nagumo’s area of responsibility encompassed the Mandates and the 

Bonins. He was also charged with the escort of maritime transport in the Central Pacific and the southeast. Nagumo was formally responsible for all combat 
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FORMOSA 30°15° 0°

0 100 200 300 400miles

Elevation in meters

KF

Army

Navy

Southern Expeditionary Fleet

xxxx

xxxx

xxxx

xxxx

xxxx

x

x

x

x

x

x

x

x xxxx

xxxx xxxx

xxxx

xxxx

xxxx

xxxx

xxxx

BURMA

THAILAND

C H I N A

FRENCH

INDO CHINA

15A

33A

Thailand Garrison Army

1 brig

Burma Area Army10 divs & 2 brigs

28A

Indo China Garrison Army

11 divs & 1 brig

xxxxx

xxx xxx xxx xxx xxx

xxx

xxx

ANDAMAN IS

BANGKOK

MANDOON

xxxx

xxx

xxx

xxx

xxx

P A C I 

F I C O C E A N

NEW GUINEA

18A

3 divs

xxxx xxxx

xxx

New Guinea Force

xxxx xxxx xxx xxxx8F SOLOMON IS

GUADALCANAL

C O R A L S E

A

160° 150° 140° 120° 110° 100°

I N D I A N O C E A N JAVA

-10°

10°

0°

20°

4F31A1 divs & 3 brigs

C A R O L I N E I S

xxx xxx xxx xxx xxx

xx

xx

xx

xx

xx

xx

xx

xx xx

xx

xx

xxxx xxxx xxxx 2F 4KF

xx

xx A R A F U R A S E A

130°

xxxx xxxx

xxxx xxxx

xxxx

xxxxx

NORTH

xx

BORNEO

xx

S O U T H

C H I N A S E

A

37A

1 brig

3FA 230 planes

B O R N E O

7HA 2 divs & 9 brigs

29A

xx

xx

xxx

xxx xxx

xxx

2HA 6 divs & 2 brigs

CELEBES

HALMAHERA

xxx

Southwest Area Fleet

LUZON

HAINAN I

25A

SUMATRA

MALAYA

MARIANA IS

LEGEND

PALAU IS

xxxx

xxxx

xxxx

17A

xxx xxx xxx xxx

Map 3: JA

PANESE SOUTHERN DEFENSE AREA

Central Pacific Area Fleet

3rd Army

Academics/jmo/2013/vego/JSDA

Map 12

Japanese southern defense 

area
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operations in the Central Pacific;98 however, in practice, the 31st Army, under Gen. 

Hideyoshi Obata, remained independent, and it in turn had exclusive tactical and 

administrative control over all army units in the Central Pacific. The 31st Army’s 

forces were deployed in “sector army groups” named for their locations—Truk, the 

Marianas, Ogasawara, and Palau.99

The Japanese failure to establish clear-cut command relationships between the 

navy and the army for defense of the Central Pacific had serious consequences for 

the defense of the Marianas against the expected invasion. From the very beginning 

there was friction about it. A final decision made on 15 March was a compromise 

between the two headquarters. Among other things, it was agreed that command of 

each island would rest in the hands of the senior officer, army or navy, present. An 

oral agreement between Nagumo and Obata stipulated that neither would assume 

complete responsibility. Hence, the Japanese had no operational level of command 

in the Central Pacific. This failure resulted in a great deal of confusion, because the 

navy and the army greatly depended on each other. For example, all installations in 

the Marianas used by naval air units were supported by army troops.100

On 23 April 1944, the Japanese reorganized their submarine force, effective two 

days later. Truk, exposed to almost daily air raids, had become unsuitable as a submarine base. All maintenance was shifted to Japan, and the headquarters of the 

Sixth Fleet was moved to Kure. Most of the frontline submarines were put temporarily under Submarine Group 7. Submarine Division 51, less three boats of 

the small RO class, was incorporated into Group 7. Afterward, Submarine Group 

7 consisted of two large I-class boats and seven RO boats. Its main mission was 

to search out and intercept enemy carrier task and invasion forces north of New 

Guinea and in the southeast, as well as to carry out operational transportation in 

the southeast.101

The Commanders

Success or failure in combat largely depends on the experience, judgment, and 

skills of the high commanders and their subordinate commanders. Admiral Nimitz 

was one of the outstanding naval leaders of World War II. He was known for his 

calm, imperturbable personality. He had a great ability to listen to diverse views 

and then to act forcefully. He was also willing to take high but calculated risks. 

Nimitz was also known for his ability to select the right personnel for key assignments.102 Nimitz was humble, polite, and gentle in manner with both subordinates 

and superiors, but he was also a very determined and decisive leader. Nimitz left 

subordinate commanders alone, because in his view looking over their shoulders 

would only inhibit them. At the same time, he made recommendations via radio if 

it appeared that subordinates were overlooking opportunities, and he did not hesitate to intervene when subordinate commanders were not performing well—or, if 

necessary, to fire them.103
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Nimitz reported directly to Admiral King. They both had great respect for each 

other. King was considered a brilliant officer and thinker, but he had an offensive 

manner and a black-and-white approach to dealing with subordinates. Though he 

got along well enough with Nimitz, King had a tendency to interfere in his responsibilities, going so far as to intervene in purely tactical matters.104

The American commanders most directly involved in what became known as 

the battle of the Philippine Sea were Admirals Spruance, Mitscher, and Lockwood. 

Spruance was one of the most able American admirals in World War II. He was 

austere, methodical, and intellectual. His remoteness was intentional.105 Spruance 

was personally extremely quiet and unassuming.106 He had a healthy prejudice 

against publicity in any form; newspaper correspondents found him colorless. His 

main traits were power of decision and coolness in action.107 Spruance had a brilliant mind that approached all problems with thorough analysis that led to decision. Spruance planned in broad terms, leaving details and minor matters of execution entirely to the discretion of his subordinates.108 He won the respect of almost 

all who came in contact with him.109 A famous American naval historian, Samuel 

E. Morison, notes that Spruance’s leading personality traits were attention to detail, 

poise, and power of intelligent decision.110

Admiral Mitscher (1887–1947) too was an unassuming man, with a soft voice 

and quiet manners. He was averse to personal glory and avoided publicity if he could. 

Mitscher was one of the pioneers of the U.S. naval aviation and had commanded the 

first carrier force in the Pacific Fleet. Admiral King said of Mitscher (his subordinate at the Bureau of Aeronautics in the mid-1930s) that he had “a personality that 

inspires confidence and loyalty. Quiet, forceful, tactful, conscientious, steady and 

practical; an asset to any organization.” This was high tribute, coming from King.111

However, Mitscher was not known for attention to detail or thorough planning. 

He could be sloppy and inattentive. Reportedly, he seldom bothered to read operation orders, preferring verbal condensations from his chief of staff, and he was 

often reluctant to accept advice. One of his greatest strengths, however, was as a 

leader of men. Few commanders were as devoted to his men as Mitscher. He earned 

devotion and admiration partly by exceptional performance and partly by unusual 

thoughtfulness and consideration toward the officers and men under him.112 In 

fact, Mitscher tended to be overly loyal to them, and that was his single greatest 

fault; apparently, it never occurred to him that a subordinate might be inept or 

incompetent.113

Admiral Lockwood (1890–1967) was another of the greatest American wartime naval leaders. After commanding several submarines in the interwar years, 

in June 1939 he was appointed as the chief of staff to Commander, Submarine 

Force, U.S. Pacific Fleet. He was sent as naval attaché to London in February 

1941; in May 1942 he was promoted to rear admiral and appointed Commander, 
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Submarines, Southwest Pacific. He was also Commander, Allied Naval Forces, 

Western Australia until July 1942. After the death of Rear Adm. Thomas English in February 1943, Lockwood became Commander, Submarine Force, Pacific 

Fleet. An aggressive and highly successful leader, Lockwood was well known for 

devotion to his submarine crews. He was promoted to vice admiral in late 1943.

The principal Japanese commanders in the A-Go operation were Adm. Soemu 

Toyoda (1885–1957) and Vice Adm. Jisaburō Ozawa (1886–1966). Toyoda was 

appointed commander in chief of the Combined Fleet on 1 May.114 He raised his 

flag at Oedo, in Tokyo Bay.115 Toyoda, born in Tokyo, graduated from the Naval 

Academy in 1905 and commanded the battleship Hiyuga in 1930. He was promoted to rear admiral in 1931, vice admiral in 1935, and admiral in 1941. Among 

many assignments, Toyoda was chief of staff of the Combined Fleet in 1933, commanded the North China Fleet in 1937, and one year later became commander 

of the Second Fleet. It was widely expected that Toyoda would get the post of 

CINC, Combined Fleet in 1941, but Adm. Isoroku Yamamoto (1884–1943) got 

that job. Most of Toyoda’s duties during the war were ashore, as the commander 

of the Kure Naval Station and the Yokosuka Naval Base and a member of the 

Supreme War Council (from May 1943) and of the Board of Admirals. Reportedly, he was highly intelligent and well informed and had opposed going to war 

with the United States. Toyoda seems to have had poor relations with the army, 

which he intensely disliked.116 COMINCH analysts formed a favorable opinion of 

Toyoda, pointing out that he had “extremely wide experience and rose by sheer 

ability” and considering him a forceful and alert officer, if extremely nationalistic 

and hostile to foreigners.117 Toyoda, fifty-nine years old in 1944, was also considered abrasive and hard-nosed. Because of the lack of combat experience, Rear 

Adm. Ryūnosuke Kusaka was assigned as his chief of staff.118

On 30 March, the fifty-seven-year-old Jisaburō Ozawa was appointed as CINC 

of the First Mobile Fleet. At the same time, he was in command of all carriers and 

directly of one carrier division—in the U.S. Navy these responsibilities would 

have been divided among three flag officers. A torpedo specialist, Ozawa had 

commanded two destroyers, a destroyer division, a cruiser, and a battleship. He 

was chief of staff of the Combined Fleet in 1937–38.119 In 1939–40 he was the 

commander of the Torpedo School, then of Carrier Division (CarDiv) 1.120 In 

1942 Ozawa led the Southern Expeditionary Fleet, which seized Malaya and the 

NEI. In 1943, he relieved Nagumo as the commander of the Third Fleet, which 

then possessed most of the carriers. In contrast to many of his peers, Ozawa 

was open-minded about naval aviation. He advocated consolidating six carriers 

under a single command, instead of the usual type command, as well as integrating battleships and cruisers with the carrier groups, following the American 

example.121
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Allied Air Strikes in the Central Pacific, January–May 1944

U.S. carrier forces and land-based aircraft of the Army Air Corps based in CENTPAC 

and SWPA conducted a series of strikes and raids against the Japanese strongpoints, 

bases, and shipping in the Central Pacific in the first six months of 1944, in support 

of the planned invasions of the Marshalls, Marianas, and Carolines. At the same time, 

submarines based in Hawaii and Australia continued their attacks against shipping 

and occasionally smaller surface combatants. The purpose was generally to weaken 

enemy airpower and cut off shipping between the home islands and the Southern 

Resources Area and naval bases and isolated strongpoints in the Central and South 

Pacific. Massive strikes by TF 58 and land-based, long-range bombers aimed to isolate areas in which major landings would take place. These strikes significantly wore 

down Japanese air strength and inflicted steady and large losses in shipping. 

On 29 January 1944, TF 58 began strikes against enemy aircraft and air installations in the Marshalls that continued until 6 February.122 On 31 January forces led 

by Spruance invaded Kwajalein and Majuro, in the Marshalls (Operation FLINTLOCK). The Southern Attack Force (TF 51, under Admiral Turner), the Northern 

Attack Force (TF 53, under Rear Adm. Richard L. Conolly), and the Reserve Force 

and Majuro Attack Group (TF 51.2, Rear Adm. Harry W. Hill) were supported by 

carrier-based aircraft of TF 58 (Mitscher) and land-based aircraft from TF 57 (Admiral Hoover). Aircraft from Task Group (TG) 58.3, under Rear Adm. Frederick C. 

Sherman, bombed aircraft and air facilities on Engebi Island and Eniwetok Atoll. 

On 1 February, U.S. forces landed on Roi, Namur, and Kwajalein.123 Roi and Namur 

were secured the next day.

On 17 February, TF 58—nine carriers and six battleships, plus accompanying 

cruisers and destroyers—conducted a series of massive strikes against Truk (Operation HAILSTONE). They destroyed 168 enemy aircraft, at the cost of only five.124

(Other sources say that at least seventy Japanese aircraft and about 200,000 tons 

of merchant shipping were destroyed.)125 The next day, U.S. forces invaded Engebi 

Island, in Eniwetok Atoll (Operation CATCHPOLE). The same day TF 58 struck Truk 

again, sinking one destroyer, one submarine chaser, and one motor torpedo boat.126

Eniwetok Island was invaded on 19 February.

On 22 February, two task groups (TGs 58.2 and 58.3) attacked Tinian and 

Guam, in the first U.S. carrier attack against the Marianas. They destroyed fiftytwo aircraft in the air, plus a large number on the ground.127 They also sank one 

transport.128 On 8 March Japanese planes bombed Eniwetok and Engebi Island, 

destroying ammunition, petroleum products, and distillation units but inflicting 

no damage on the airstrip.129

Because of the strikes on Truk, Admiral Koga was greatly concerned about a 

possible attack on Palau and ordered his heavy surface forces to avoid air attacks. 
J

Koga was proved correct when U.S. aircraft struck Palau on 30 March. In response, 

Koga issued a general order activating “HEI operation, Method 6, Method D” (i.e., 

interception of the enemy fleet by the surface striking force in the western Carolines). Eight submarines (five I class and three ROs) were assigned to patrol in the 

Marshalls; one submarine (I class) sortied from Truk, the remaining six (one I, five 

ROs) at Truk being unavailable for immediate operations. All available submarines 

in home waters (three I-boats and four ROs) were directed to advance to the Palau 

area.130

On 30 March and 1 April, TF 58 conducted large-scale air attacks of airfields, 

shipping, and fleet and air installations at Palau, Yap, Ulithi, and Woleai. The attack on Palau was designed primarily to destroy enemy naval ships and aircraft; 

the attacks on Yap, Ulithi, and Woleai were secondary in importance. TF 58 had 

eleven carriers organized in three task groups, whose strikes were supplemented by 

strikes and long-range searches by aircraft from CENTPAC and SWPA. The U.S. 

submarines were directed to attack shipping, conduct reconnaissance, and provide 

lifeguard services for aviators.131 U.S. carrier aircraft also extensively mined the 

channels into the Palaus, the first time that carrier aircraft laid mines. TF 58 planes 

sank and damaged a fairly large number of the ships at Palau and Angaur.132 On 31 

March, one carrier group attacked Yap, Ulithi, and Ngulu, and on 2 April all three 

groups attacked Woleai. Some 150 enemy aircraft were destroyed in the air and on 

the ground, at the loss of only twenty-five U.S. aircraft.133

On 21–22 April, TF 58 bombarded airfields and defensive positions in the Hollandia, Wakde, Sawar, and Sarmi areas of New Guinea in support of landings at 

Aitape and Tanahmerah Bay (Operation PERSECUTION) and Humboldt Bay, Hollandia (RECKLESS).134 On 29–30 April a force from TF 58 composed of five fleet 

carriers and seven light carriers struck the shipping, oil and ammunition dumps, 

aircraft facilities, and other installations at Truk.135 The plan was to conduct daily 

fighter sweeps by eighty-four planes and then staggered bombing attacks. There 

was considerable opposition to the initial fighter sweep, as well as squally weather 

and heavy cloud cover, but by midmorning all airborne enemy planes had been 

eliminated. Some 2,200 sorties were flown. The 23rd Air Flotilla on Truk lost about 

sixty aircraft in the air and thirty-four more on the ground. Some 170 naval personnel were killed and three hundred wounded. TF 58 lost twenty-seven planes, 

mostly from antiaircraft (AA) fire.136

On 30 April, nine heavy cruisers and eight destroyers were detached from TF 58 

to bombard positions on Satawan Island, in the Namoi group in the Carolines. On 

1 May, TGs 58.1 and 58.7, with seven battleships and fourteen destroyers, attacked 

wharf areas, a seaplane base, and other installations on Ponape Island.137

On 13–14 May, carrier aircraft and B-24s and B-25s of the U.S. Army Air Forces 

bombed installations at Jaluit.138 On 19–23 May a TF 58 carrier group carried out a 
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series of strikes against Marcus and Wake. On the 19th, night fighters attacked Marcus; these attacks continued during the next day. On the 20th composite groups attacked Marcus, causing moderate damage to buildings and installations but shooting down few enemy planes, at a loss of four aircraft. The small results were due to 

a lack of targets and bad weather. An attack on Wake was carried out by composite 

groups on 23 May; a number of ground installations were destroyed or damaged.139

Allied Knowledge of the Enemy prior to 30 May

The U.S. intelligence activities in Hawaii and Washington, D.C., had a fairly accurate picture of the IJN’s organizational changes, plans, and orders and of the movements of various forces for many months prior to June 1944. The main sources 

of information were intercepts of enemy radio transmissions, direction finding 

and sightings by long-range bombers and seaplanes, as well as reconnaissance patrols by submarines. Admiral Nimitz at Pearl Harbor and all fleet and task force 

commanders in the theater received Joint Intelligence Center Pacific Ocean Area 

(JICPOA) daily bulletins. (The times used in reference to these bulletins are always 

“minus nine” unless otherwise indicated.) Admiral King in Washington was kept 

informed of Japanese plans and intentions through COMINCH daily summaries 

of radio intercepts. These were based on information transmitted to his staff by 

Nimitz and JICPOA, whose analysts were able either to learn directly about or to 

deduce all major movements of the Combined Fleet in the NEI, the Philippines, 

New Guinea, and the Central Pacific. Radio intercepts were also very helpful in 

decrypting messages sent by the CINC of the Combined Fleet to seagoing forces 

and shore commands. The biggest success was the reading of the Combined Fleet’s 

actual plan to react to the Allied advances across the Central Pacific. 

On 30 December 1943, COMINCH analysts learned that the Japanese NGS 

had shifted its emphasis to offensive air operations. The Japanese, they found, were 

contemplating the creation of a new Carrier Division 3, composed of two escort 

carriers (Chitose, Chiyoda) and one light carrier (Zuihō). The Japanese also intended to have in service twenty-one fighter squadrons and nine torpedo-bomber 

squadrons.140 On 22 January 1944, the same analysts learned from radio intercepts 

that the Japanese had established the First Air Fleet, responsible for patrolling the 

eastern approaches to the home waters. They believed the First Air Fleet consisted 

of about six hundred aircraft and two major training commands (the Fiftieth and 

Fifty-First Air Fleets), the Yokosuka Air Group, and two unidentified groups of 

fighters and medium bombers.141

On 21 February 1944, COMINCH’s daily radio-intercept summary noted that 

Battleship Division (BatDiv) 3, comprising Kongo, Haruna, and possibly Yamato,

was at Singapore, part of the Third Fleet. Total Japanese strength in the Singapore 

area was estimated at five battleships, two large carries, four heavy cruisers, five 

light cruisers, and seventeen destroyers.142 COMINCH also learned on 27 February 
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that the Japanese had started preparations to reinforce their defenses of the Carolines and Marianas. The 29th Army Division was being transported in three large 

convoys, thirty vessels, to Saipan and Truk.143

Also on 27 February, COMINCH analysts discerned that the enemy fleet was 

in the process of a major reorganization. They learned that the First Fleet had been 

disbanded, as noted above, and that the First Mobile Force (often called the “First 

Striking Force” in JICPOA/COMINCH intelligence assessments), formed from the 

(disbanded) First and Second Fleets, would be assigned to the Combined Fleet effective the 1st.

On 28 February, JICPOA reported that BatDiv 1 had been assigned to the newly 

reconstituted Second Fleet. The battleship division had been part of the First Striking Fleet. The battleship Nagato had been shifted to BatDiv 1 from BatDiv 2 on 25 

February.144 On 25 March, all the Japanese submarines operating in the Central 

Pacific–Solomons–New Guinea area were reported to have come under direct tactical control of the Sixth Fleet.145

On 25 March, COMINCH’s daily radio-intercept summary reported that a new 

2nd Air Attack Force had been created, subordinate to CINC, First Air Fleet and 

with headquarters on Tinian.146 This unit, its forces deployed through the Marianas–

Truk–Mereyon–Peleliu area, consisted of 302 aircraft.147 The 2nd Air Attack Force 

was responsible for air defense of the eastern Carolines, Marianas, and the Bonins. 

In addition, a part of the Yokosuka Air Group, normally assigned to home defense, 

had been deployed to Marcus and Iwo Jima.148 COMINCH analysts had already 

learned the First Mobile Force had been created, but they mistakenly assessed that 

its principal mission was the protection of communications. They correctly projected, however, that it would concentrate in the southern Philippines by 10 May.149

They believed that the First Mobile Force consisted of the First Mobile Fleet (Daiichi Kido Kantai) and the battleship Fusō (because JICPOA’s reports referred to 

some Japanese units differently than their true designations, “First Mobile Force” 

and First Mobile Fleet” are used interchangeably in the following account).150 It was 

reported that the headquarters of CINC, Combined Fleet, temporarily on Palau, 

were to be moved to Saipan via Davao during the evening of 31 March or the morning of 1 April.151

On 30 March, COMINCH analysts learned that all submarines available in 

home waters and Truk had been directed to the vicinity of Palau. The next day, six 

to seven submarines in home waters were directed east of Palau. American naval 

analysts did not know how many submarines would sortie from Truk but believed 

about five boats could be available. A day later, they deduced that the Japanese were 

preoccupied with defensive measures because of the presence of the U.S. striking 

force in the Palau area; they had directed all available naval forces in the Singapore area, plus submarines in home waters and at Truk, to proceed to the southern 
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Philippines to attack enemy “occupation forces.” Specifically, CarDiv 1 (with seventy fighters, sixty-five dive-bombers, and fifty torpedo bombers) would proceed 

to Davao via Balikpapan and then seek out and destroy enemy carriers. The 2nd 

Diversionary Attack Force—four BBs (Nagato, Fusō, Kongo, and Haruna), five CAs 

(Tone, Chikuma, Suzuya, Kumano, and Mogami), one light cruiser (CL, Yahagi), 

and ten destroyers (DDs) would sortie out from the Singapore–Lingga area to the 

southern Philippines to destroy U.S. occupation forces, concentrating on the carriers. Except for two heavy cruisers and about four destroyers, this force was under 

the command of BatDiv 1.152

On 2 April, JICPOA revealed that starting on 31 March the Japanese had conducted communications-deception measures to conceal the movement of the 

601st Air Group on board CarDiv 1 from Singapore to Davao and of surface forces 

from Singapore–Lingga to the southern Philippines.153 The projected move of the 

Sixth Fleet’s headquarters from Truk to Palau was postponed until the end of April 

because of damage suffered at Palau during recent carrier strikes.154 On 3 April, 

COMINCH analysts noted that the 2nd Diversionary Attack Force was proceeding 

to the southern Philippines from the Singapore–Lingga area. The units of Southeastern Area Fleet—one CA (Aoba), one CL (Ōi), and two DDs—had departed 

Singapore on 2 April and were en route to Balikpapan, to arrive on 4 April.155

On 4 April, COMINCH intelligence reported that the Japanese had deduced 

that the Allies would not conduct a landing on the Palaus. This had led Koga to 

cancel all preparations to seek out and destroy U.S. “occupation forces.” An important piece of information was that the Tawi-Tawi anchorage in the Sulu Archipelago would be used as a major fleet anchorage in the defense of the Philippines. 

The 33rd Guard Division has been assigned to the 32nd Base Force at Davao to set 

up defenses and facilities at Tawi-Tawi.156 JICPOA correctly assessed that the enemy intended to speed up army reinforcement to the Central Pacific, western New 

Guinea, and the Philippines. It also had evidence that the Japanese believed that 

the Allies would probably conduct landings at Wewak and Hollandia in the near 

future. These landings would be coordinated with air strikes against the Palaus.157

On 6 April, COMINCH noted Japanese efforts to replace aircraft destroyed in 

the strikes against Palau, Mereyon, Woleai, and Truk. The Japanese also planned 

to set up adequate antiair defenses and to strengthen antisubmarine defenses. The 

Japanese redeployed most of the aircraft in the Marianas and on Iwo Jima to these 

forward air bases; few if any replacement aircraft arrived from Japan.158 On the same 

day, JICPOA learned that the 2nd Diversionary Attack Force—five CAs (Atago, 

Takao, Chokai, Haguro, Myoko), one CL (Noshiro), and four or five DDs—had 

departed from Davao on the evening of the 5th. Four days later this force, after 

passing through the Basilan Strait and Balabac Strait, would arrive at the Lingga 

anchorage. This force had left Palau prior to the U.S. strikes.159
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On 7 April, COMINCH intelligence was in the dark about the whereabouts of 

the CINC, Combined Fleet, Adm. Mineichi Koga. Traffic analysis had been unable 

to locate him since 3 April. The analysts noted an extensive search for an aircraft 

belonging to the 851st Air Group lost en route from Palau to Davao at the approximate time when Koga was scheduled to move his headquarters. An indication that 

Koga had been lost was that CINC, Central Pacific Area Fleet at Saipan seemed 

to have taken charge and issued orders, even to Combined Fleet staff officers.160

Koga had indeed died in a crash, but it was actually Vice Adm. Shirō Takasu, Koga’s 

deputy and the commander of the Southwest Area Fleet at Surabaya, who took over 

command of the Combined Fleet, for about a month.161

Also on the 7th, the COMINCH team reported “excellent” evidence that the 

major part of the Japanese fleet at Singapore–Lingga would return to the southern 

Philippines, probably Tawi-Tawi, shortly after 15 April. The indications were that 

four tankers assigned to the First Mobile Fleet had been ordered to proceed to 

Balikpapan as expeditiously as possible, take on full loads, and stand by for further 

orders from 15 April. Another important item was an order for the shipment of 

radar tubes to Davao after 15 April.162 Orders to the heavy cruiser Maya and three 

DDs to depart from Yokosuka by 15 April and proceed to the southern Philippines 

indicated that the 2nd Diversionary Attack Force would also return there. Further, 

the Southwest Area Fleet was directed on 6 April to transport troops, under the 

escort of Cruiser Division (CruDiv) 16—one CA, four CLs, and two DDs—from 

Davao to Tawi-Tawi.163 Nimitz believed that these troops were intended to mop up 

guerrillas in preparation for using Tawi-Tawi as a fleet anchorage.164

On 8 April, Nimitz’s staff believed that CarDiv 3 (Zuihō, Chitose, and Chiyoda)

would not be ready for combat operations prior to 15 April. There was additional 

evidence that the First Striking Fleet would move to the southern Philippines from 

the Lingga anchorage, probably after 15 April.165 COMINCH analysts noted that 

the Japanese continued intensive work on new airfields in the Marianas; more than 

a hundred aircraft of the 62nd Air Flotilla were expected to be sent to that area during April. By the 15th a new air base at Rota would be almost complete; it would 

have one eighty-by-1,500-meter runway, taxiways, and barracks for a thousand 

men. The airfield on Guam was not yet complete, but COMINCH analysts estimated that some eighty-three planes, mostly dive- and torpedo bombers, would be 

based there in the near future.166

On 12 April, the COMINCH daily radio-intercept summary had definitive information that the 2nd Diversionary Attack Force had been directed to sortie from 

the Singapore area on 31 March and proceed to Tawi-Tawi.167 Also, the volume of 

Japanese radio traffic had built up in the southeastern area, possibly related to the 

planned shift of most heavy ships then in the Singapore–Lingga area to Tawi-Tawi 

on 15 April.168
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On 30 April, COMINCH radio intercepts indicated that CarDiv 2 and CarDiv 3 

were in the Inland Sea.169 Radio traffic on 27 and 28 April showed that both CarDivs 

had been making final preparations for sailing to Singapore via Manila. Contrary to 

previous indications, it now appeared that CarDiv 2 would sortie first. COMINCH 

analysts also learned that the First Mobile Fleet had directed CarDiv 2 to transfer 

some fifty replacement aircraft (twenty fighters, eighteen dive-bombers, and twelve 

torpedo bombers) to CarDiv 1 off Manila, probably between 6 and 10 May.170

On 2 May, JICPOA assessed that a movement of the First Striking Fleet from 

the Singapore area to the Philippines could be impending. CarDivs 2 and 3 had 

completed combat training in Japan and would probably depart about that day; 

they might proceed with the battleship Musashi and eight DDs. CarDivs 2 and 3 

would ferry planes for CarDiv 1, and at least some of them would be transferred by 

lighters off Manila. These two divisions would then probably join the First Striking Fleet in the Singapore–Philippines area. On 30 April, it was now reported, the 

commander of the First Striking Fleet had directed various tankers to an unknown 

place in the Sulu Archipelago, probably Tawi-Tawi. Nimitz estimated that the First 

Striking Fleet would depart the Singapore area about 7 May and proceed to, most 

likely, Tawi-Tawi.171 Fuel reserves were being built up there; three large fleet tankers 

were then loading at Balikpapan under orders to proceed to Tawi-Tawi. In all, six 

tankers and one cargo vessel had received orders to sail for Tawi-Tawi.172

On 8 May, JICPOA had indications that CINC, First Mobile Fleet and units 

under his command had left Singapore and were proceeding in several sections for 

Tawi-Tawi. JICPOA believed that CruDiv 7 would depart Singapore for Manila. 

Practically all fleet units then in the Singapore area would sortie for Davao, TawiTawi, or Manila. JICPOA also estimated that Musashi, CarDiv 2, and CarDiv 3, plus 

about eight DDs then in Japan, would join other units. All together, the Japanese 

would have in the southern Philippines a force of six BBs, two large carriers, two 

auxiliary carriers, five light carriers, eleven CAs, and twenty to twenty-five DDs. 

Most of the tankers were servicing the fleet at Tawi-Tawi and Manila; they were 

escorted by destroyers. Air cover was being given to the convoys proceeding from 

Balikpapan to Tawi-Tawi, in addition to surface escorts.173

COMINCH analysts learned on the 9th that the First Mobile Fleet had sortied 

from Singapore to the southern Philippines two days earlier. Up to fifteen tankers had been diverted from other duties and concentrated near Balikpapan and 

the southern Philippines.174 JICPOA informed all task force commanders and the 

commanders of SWPA and SOPAC that Nimitz believed that Jolo Airfield in Sulu 

Archipelago had been developed by the Japanese as a rear base.175 JICPOA learned 

that enemy intelligence had deduced that Allied operations were imminent, probably in the Central Pacific area and possibly involving landing operations. Hence, 

on 13 May the Japanese alerted the defenses of the Marianas.176
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On 12 May, JICPOA revealed that on 4 May, the chief of the NGS had reported an 

urgent need for a delivery that month of aviation gasoline, aerial bombs, torpedoes, 

and machine-gun ammunition to air bases in the Marianas and the eastern and 

western Carolines. He also requested from CINC, Combined Fleet all possible assistance in the transportation, loading, and assembling of the material. COMINCH 

analysts commented that the nineteen airfields listed in that message included two 

airfields on each of the islands of Saipan, Tinian, Mereyon, Harushima, Truk, Palau, and Peleliu.177 They also noted evidence of a serious shortage of crude oil at 

Balikpapan refineries. A message sent by the Balikpapan fuel depot on 11 May revealed that though seventy thousand tons of oil per month from Java and Sumatra 

was necessary, only fourteen thousand tons had actually been received from Java in 

April; in May it would be 14,300 tons. No oil had been received from Sumatra. The 

apparent reason for that situation was the lack of ships to transport the crude oil.178

JICPOA had fairly good evidence that the Japanese contemplated eventual completion of four airfields on Guam and three on Saipan, four on Tinian, three on Iwo 

Jima, two on Puluwat, and two on Ponape, four on Yap, four on Woleai, and five 

on Truk.179

On 13 May, Nimitz informed subordinate task force commanders that the majority of the First Striking Fleet and Second Fleet had probably not sortied on the 

7th; possibly some Second Fleet units had left the Singapore–Lingga area and were 

on that date in the Makassar Strait–Celebes Sea area. The Japanese plan to transfer 

CarDiv 1 replacement planes from CarDiv 2 units off Manila had been canceled, 

and the movement of CarDivs 2 and 3 from the Inland Sea, and of Musashi from 

the Philippines, had apparently been postponed. However, there were indications 

that these two carrier divisions had left the Inland Sea about noon on 11 May. 

CarDiv 1 and Mogami had been off Borneo’s west coast on 12 May. Some aircraft 

of the 601st Air Group on board CarDiv 1 and shore-based aircraft had arrived at 

Davao on 12 May.180

On 16 May, COMINCH’s analysts had indications that the Japanese planned to 

concentrate the major part of their fleet in the southern Philippines, with CINC, 

Combined Fleet at Davao. They also had information that the First Air Fleet, then 

deployed in the Saipan–Tinian area, would move its units to Palau and Davao.181

JICPOA learned that Japanese intelligence believed that the U.S. striking force had 

departed the Marshalls on or before 15 May; if had issued a warning to certain 

Central Pacific bases in anticipation of strikes.182

On 19 May, COMINCH’s analysts learned that on 4 May the chief of the 1st 

Section (Operations Bureau) of the NGS had requested Admiral Toyoda to pay special attention to the transport of fuel and ammunition to various bases within the 

Saipan–Truk–Tawi-Tawi–Ambon quadrangle. The pending operation demanded that these supplies be accumulated during May at various listed bases.183 The 
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Advance Expeditionary Force (Submarines) would patrol the Marshalls and north 

of Mussau Island (the Saint Matthias Group, New Guinea), as well as Wevak.184

On 21 May, Nimitz assessed that Southern Army Headquarters had moved 

from Singapore to Manila early in the month. The 22nd, 23rd, and 26th Air Flotillas had been assigned to the First Air Fleet. At least part of the 61st Air Flotilla had 

deployed from the Marianas to Palau. The 22nd Air Flotilla had deployed at Truk, 

the 23rd Air Flotilla to Sorong, the 26th Air Flotilla from Palau to Davao, and the 

61st Air Flotilla to Palau and the Marianas. All these air flotillas were subordinate 

to the commander of the First Air Fleet, on Tinian.185 The 25th Air Flotilla, formerly at Rabaul, had been dissolved. These redeployments of air flotillas, Nimitz 

felt, suggested that the Japanese believed that Palau and western New Guinea were 

most likely Allied objectives.186

On 21 May, COMINCH analysts learned that CINC, Southeast Area Fleet sent a 

message stating that during the pending “A-Operation” (to counter an Allied invasion of the Marianas), every effort would be made to have at least two airfields at 

Rabaul usable by the evening of each day, though they had been attacked during the 

day. The analysts commented that the “nature of A-Operation is unknown” but that 

there was no indication that it would be more than local in scope. They believed 

(erroneously) that it might be related to supply or evacuation operations in the 

Bismarcks and Solomons.187

On 22 May, JICPOA reported a major reorganization of the Japanese air commands. The First Air Fleet appeared to have assumed administrative and tactical 

command of all shore-based naval aircraft in the Marianas, Carolines, and southern Philippines, Halmahera, the Celebes, and western New Guinea. The CINC of 

the Central Pacific Area Fleet had been stripped of all but a few transport aircraft. 

This was the first time that senior air command had been divorced from area fleets. 

Subordinate to the First Air Fleet were the 22nd Air Flotilla, the 2nd Air Attack 

Force on Truk, the 23rd Air Flotilla (or 3rd Air Attack Force) at Sorong, the 26th 

Air Flotilla (or 6th Air Attack Force) at Davao, and the 61st Air Flotilla (or 41st 

Air Attack Force) on Palau. However, JICPOA erroneously concluded that the air 

deployments indicated that the Japanese considered assaults on Guam, Tinian, or 

Saipan less likely than on Palau, in the southern Philippines, or at some place in 

that vicinity, such as Manokwari (on the Vogelkop Peninsula) or Halmahera.188

On 22 May, JICPOA estimated that Japanese air strength in the Philippines, 

NEI, and New Guinea was about 1,060 aircraft. This figure included some 450 aircraft (225 fighters, 216 single-engine bombers, and nine floatplanes) embarked on 

CarDivs 1, 2, and 3.189 The 5th Base Air Force’s Vice Adm. Kakuji Sumida was in 

command of the 61st Air Flotilla, with headquarters on Tinian. The 11th Air Flotilla and the 26th Air Flotilla commanders were on Truk and Palau, respectively, 

responsible for operations in the Carolines and the Marianas. The 23rd Air Flotilla, 
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with headquarters at Kendari, in the Celebes, was operating north of Australia.190

The base air forces had some 372 aircraft, while the army had 234.191 However, 

JICPOA was having difficulty estimating Japanese air strength in the Marianas and 

Carolines, because of uncertainty about the movements of the 61st Air Flotilla from 

Saipan, Guam, and Tinian. On 1 May, that flotilla consisted of ten air groups and 

670 aircraft. Its combat strength had been increased by superbly trained units of 

the Thirteenth and the Fourteenth Air Fleets.192 JICPOA assessed that the Japanese 

had in that area 384 aircraft (186 fighters, sixty single-engine bombers, seventy-two 

twin-engine light bombers, sixteen medium bombers, eight flying boats, and fortytwo floatplanes).193

On 27 May, as Nimitz informed task force commanders, there was no change 

in the location of the enemy fleet commanders, with the exception of Commander, 

First Striking Force and Commander, Second Fleet. They were estimated to be at 

the Tawi-Tawi anchorage. From the information received from U.S. Seventh Fleet 

on 24 May, it was believed that there were some forty vessels at Tawi-Tawi, including six carriers and ten battleships and cruisers.194

On the 29th, JICPOA noted numerous flights from the home islands to the 

Marianas. It estimated total Japanese air strength at 550 naval land-based aircraft 

(including 250 fighters, 120 single-engine bombers, eighty twin-engine light bombers, and fifteen medium bombers), 370 army planes, 1,290 naval local-patrol and 

training aircraft, and 120 army aircraft in training.195 The Yap airfield had assumed 

increased importance for basing fighter aircraft. After mid-May some fighters were 

moved from Guam and Tinian to Palau.196

A most important development was the Allied capture of a copy of the Combined Fleet’s plan to counter the U.S. offensive in the Central Pacific—Combined 

Fleet Secret Order No. 73, code-named Z operation, issued by Admiral Koga on 

8 March 1944. On 29 May, JICPOA made translations available to all major commanders in the POA. Allied intelligence believed that the basic strategic principles 

still held good in May 1944.197 An early Z plan had been signed by Koga on 25 August 1943. In February 1944, Koga obtained approval by IGHQ to modify it to meet 

the changed strategic situation in the Pacific. He was also allowed to command the 

Combined Fleet from Truk instead of Tokyo.198

The Z plan was captured by Filipino guerrillas on Cebu Island led by the U.S. 

Army lieutenant colonel James M. Cushing on 3 April. This happened through an 

accident. Faced with an imminent attack on ships anchored in the Palaus, Koga had 

ordered all warships and merchant ships to leave on 29 March and had transferred 

his headquarters ashore. Not wanting to be isolated on Palau, however, he decided 

to move his headquarters to Davao, some six hundred miles west. On the 31st, 

Koga and his staff flew there in three planes. Only one reached its destination. Koga’s plane ran into a violent tropical storm and crashed on the way to Davao; there 
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were no survivors. The second plane carried his chief of staff, Vice Adm. Shigeru 

Fukudome, with the Z plan in a briefcase, and fourteen staffers. This plane too 

encountered bad weather, and it crashed in the Bohol Strait, two and a half miles 

from Cebu, at about 0230 on 1 April.199 Fukudome and twelve members of his staff 

survived. The Japanese headquarters on Cebu was only about six miles away from 

where they swam ashore, and two survivors made their way there. Fukudome and 

ten others, however, were rescued by Filipino fishermen.200 They were taken to the 

87th Regiment of the Filipino guerrillas and held as prisoners at Barrio Balud, near 

Cebu City. For some reason, Lieutenant Colonel Cushing, who was in command, 

was under the impression that Fukudome was in fact Gen. Twami Furonei, commander of the army and naval forces at Makassar. On 3 April, however, a Filipino 

shopkeeper at Perios, a village near Barrio Magtalisay, saw in the water what turned 

out to be Fukudome’s briefcase and retrieved it.201

The Japanese commander on Cebu learned about the crash from the two 

survivors who reached him and deployed three battalions to search for the other 

survivors. Cushing prevailed on Fukudome to send them a message that the 

guerrillas would release the prisoners if the Japanese stopped slaughtering civilians. That led to the release of the Japanese prisoners, including Fukudome. 

All of them arrived safely at Cebu, then at Manila, and eventually Tokyo, on 20 

April.202

The U.S. submarine Haddo was sent secretly to pick up Fukudome’s briefcase, 

plus some forty Americans. Haddo reached Darwin, Australia, on 19 May, and the 

briefcase was flown to Brisbane. The SWPA’s Allied Intelligence Bureau sent the 

document to the Allied Translator and Interpretation Section (ATIS). On 23 May, 

ATIS published a limited-distribution translation; five days later, “A Study of the 

Main Features of Decisive Air Operations in the Central Pacific,” which had been 

completed by the Combined Fleet staff on 10 March 1944, was issued on a limited 

basis to major commands in both SWPA and POA.203

On 29 May, JICPOA provided a detailed rundown of ships believed to be in 

the Philippines–NEI area: six battleships (Musashi, Yamato, Nagato, Kongo, 

Haruna, Fusō), eight carriers (Shōkaku, Zuikaku, Hitaka, Taihō, Ryuho, Zuihō, Chitose, Chiyoda), twelve CAs (Atago, Takao, Maya, Chokai, Haguro, Myoko, Kumano, 

Suzuya, Tone, Chikuma, Aoba, Mogami), five CLs (Kinu, Ōi, Yubari, Noshiro, 

Yahagi), and thirty-three DDs.204 The JICPOA analysts estimated that CarDiv 2’s 

training was behind that of CarDivs 1 and 3 and that as of the end of April it would 

probably have had difficulty conducting strikes. CruDiv 5 had been assigned an 

anchorage at Palau, the first use of Palau by major ships since the U.S. strikes at the 

end of March.205 JICPOA estimated that the three Japanese carrier divisions had 

on board 225 fighters, 117 dive-bombers, ninety-nine torpedo bombers, and nine 

reconnaissance aircraft.206
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On 29 May, JICPOA estimated that in the event of U.S. operations in the Central Pacific, it was the Japanese plan to advance either the whole First Mobile Fleet 

or just carrier forces, depending on the fuel situation. The Japanese tanker shortage, while difficult, was not sufficiently acute to prevent such a move. It was also 

believed that under conditions of tactical advantage, Japanese forces would prefer 

a night action and that their carriers would take a circuitous approach and attack 

from the flank. Much, however, would depend on the availability of shore-based air 

after the initial strikes.207 JICPOA reported that in the Central Pacific the Japanese 

had reduced air searches from six hundred miles to between three hundred and 350 

miles during the critical hours prior to dawn and late in the afternoon. Another 

factor was shortage of medium bombers. The use of dive-bombers and carrier torpedo bombers in predawn searches out to 300–350 miles appeared to be regular 

doctrine at key bases such as Truk and Tinian.208

At 0215 on 29 May, Nimitz’s headquarters advised subordinate commands that 

the Japanese had sped up construction of a second airfield at Yap. He believed that 

CruDiv 5 and the battleship Fusō would soon arrive at Palau from the southern 

Philippines. In another message at 0321, his headquarters reported that CruDiv 7 

was in the Philippines and that Japanese radio intelligence in the Philippines believed that an important U.S. task force had been in the Marshalls on 27 May. The 

next day, Japanese communications-intelligence units throughout the Central Pacific, the home islands, and the Kurils warned that forces should be in readiness for 

joint action—another indicator that the Japanese expected a major U.S. operation 

would happen shortly. It also implied that the Japanese had made preparations for 

a fleet action to counter such an operation.209

Finally, on 31 May Nimitz’s headquarters informed subordinate commands that 

there was evidence of Japanese fuel shortages in the Marianas. The Japanese would 

soon start work on a 1,200-meter airstrip on Palau. On 30 May, a convoy of the 

transport ships believed to be carrying First Air Fleet base and air personnel had 

departed Saipan for Palau. This shift in the weight of effort suggested to JICPOA 

analysts that the Japanese believed that the next major U.S. operation would be in 

the Palau–western New Guinea area.210
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NOTES 1 Worrall Reed Carter, Beans, Bullets and Black Oil: 

The Story of Fleet Logistics Afloat in the Pacific during World War II (Washington, D.C.: U.S. Government Printing Office [hereafter GPO], 1953), p. 

137; Juergen Rohwer and Gerhard Huemmelchen, 

Chronology of the War at Sea 1939–1945: The Naval 

History of World War Two, 2nd rev. and exp. ed. 

(Annapolis, Md.: Naval Institute Press, 1992), p. 286.

2 Philip A. Crowl, United States Army in World War II: 

The War in the Pacific—Campaign in the Marianas

(Washington, D.C.: Office of the Chief of Military 

History, Department of the Army, 1960), p. 3.

3 Ibid.

4 The American-British-Canadian staff talks were 

held in Washington, D.C., from January through 

March 1942.

5 Crowl, Campaign in the Marianas, p. 3. The discussion that follows (until the next citation) is based on 

this source, pp. 7–9, 12–15.

6 Admiralties: Operations of the 1st Cavalry Division (29 February–18 May 1944), CMH Pub 100-3 

(Washington, D.C.: U.S. Army Center of Military 

History, 1990 [first printed by the Historical 

Division, War Department, for the American Forces 

in Action Series, 1946]), p. 10.

7 Crowl, Campaign in the Marianas, p. 15.

8 Ibid.

9 MacArthur’s three-phase plan of advance from the 

Bismarcks into Mindanao was drafted in March 

1944. Louis Morton, U.S. Army in World War II: 

The War in the Pacific—Strategy and Command: The 

First Two Years, CMH 5-1 (Washington, D.C.: U.S. 

Army Center of Military History, 1989), p. 514.

10 Crowl, Campaign in the Marianas, p. 16.

11 Cited in ibid., p. 17.

12 Bernard D. Cole, “Struggle for the Marianas,” Joint 

Force Quarterly (Spring 1995), p. 87.
J

13 Cited in Crowl, Campaign in the Marianas, p. 17. 

The discussion that follows (until the next citation) 

is based on this source, pp. 2, 18–19.

14 Cole, “Struggle for the Marianas,” p. 89.

15 Crowl, Campaign in the Marianas, p. 1.

16 Gordon L. Rottman, World War II Pacific Island 

Guide: A Geo-military Study (Westport, Conn.: 

Greenwood, 2002), p. 323.

17 Ibid., pp. 323, 349. 

18 Ibid., p. 348.

19 Ibid., p. 349.

20 Robert W. Robson, The Pacific Islands Handbook 

1944 (New York: Macmillan, 1945), p. 147.

21 Ibid., p. 150.

22 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” 8 September 1944, p. 16, folder 

2461-D, box 117, nos. 2461–2470, Record Group 

[hereafter RG] 4, Publications, Naval Historical Collection, Naval War College, Newport, R.I. [hereafter 

NHC NWC].

23 Ibid., p. 17.

24 Rottman, World War II Pacific Island Guide, p. 370.

25 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” p. 19.

26 Ibid., p. 18.

27 Rottman, World War II Pacific Island Guide, 

p. 372.

28 Ibid., p. 385.

29 Ibid., pp. 376, 380–81.

30 Neal M. Bowers, “The Mariana, Volcano and Bonin 

Islands,” in Geography of the Pacific, ed. Otis W. 

Freeman (New York: Wiley, 1951), p. 210.

31 Commander Fifth Fleet April 1944 to April 1945, 

Aerological Plan, annex E, appendix I, p. E-I-4, 

folder April–May 1944, box 32, RG 38, Records 

of the Office of the Chief of Naval Operations, 

Records Relating to Naval Activity during World 

War II, World War II Diaries, National Archives and 

Records Administration, Washington, D.C. [hereafter NARA]. [Hereafter Commander Fifth Fleet 

Aerological Plan.]

32 Ibid.

33 Bowers, “Mariana, Volcano and Bonin Islands,” 

p. 210.

34 Commander Fifth Fleet Aerological Plan, p. EI-6.

35 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” p. 9.

36 Rottman, World War II Pacific Island Guide, pp. 

394–95.

37 Robson, Pacific Islands Handbook 1944, p. 142.

38 Rottman, World War II Pacific Island Guide,

p. 145.

39 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” pp. 25–26.

40 Ibid., pp. 20–21.

41 Curtis A. Manchester, Jr., “The Caroline Islands,” in 

Geography of the Pacific, ed. Freeman, p. 236.

42 Rottman, World War II Pacific Island Guide, 

p. 398.

43 Robson, Pacific Islands Handbook 1944, p. 146.

44 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” p. 27.

45 Robson, Pacific Islands Handbook 1944, p. 145.

46 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” p. 27.

47 Ibid., p. 25.

48 Manchester, “Caroline Islands,” pp. 239, 241.

49 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” p. 25.

50 Ibid., p. 28.

51 Rottman, World War II Pacific Island Guide, p. 372.

52 Ibid., pp. 411–12.

53 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” p. 16.

54 Ibid., pp. 18–19.

55 Ibid., p. 17.

56 Ibid., p. 15.

57 Commander Fifth Fleet April 1944 to April 1945, p. 

18, folder April–May 1944, box 32, RG 38, Records 

of the Office of the Chief of Naval Operations, Records Relating to Naval Activity during World War 

II, World War II Diaries, NARA; Rottman, World 

War II Pacific Island Guide, pp. 380–81.

58 Commander Fifth Fleet April 1944 to April 1945, 

p. 18.

59 Samuel Eliot Morison, History of United States Naval 

Operations in World War II, vol. 13, New Guinea and 

the Marianas, March 1944–August 1944 (Boston: 

Little, Brown, 1953), p. 238.

60 Commander Fifth Fleet April 1944 to April 1945, 

p. 18.

61 Staff Presentation, “Strategic Area of Islands of the 

Central Pacific,” p. 25.

62 Ibid., pp. 21–22.

63 Commander Fifth Fleet April 1944 to April 1945, 

p. 18.

64 British Admiralty, Naval Intelligence Division, Netherlands East Indies, Geographical Handbook Series 

(Liverpool, U.K.: C. Tinling, April 1944), vol. 1, pp. 

125–26.

65 Staff Presentation, “The Strategic Area of the Philippines and the East Indian Islands,” p. 13, folder 

2461-F, box 117, RG 4, NHC NWC.

66 Department of Intelligence, Studies in Strategic 

Areas: The Philippine Islands (Newport, R.I.: Naval 

War College, 1936–37), pp. 9, 54–55, folder 2059, 

box 77, RG 4, NHC NWC.

67 Ibid., p. 57.

68 Richard W. Bates et al., The Battle for Leyte Gulf, 

October 1944: Strategical and Tactical Analysis, vol. 

1, Preliminary Operations until 0719 October 17th 

including Battle off Formosa (Newport, R.I.: Naval 
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War College, 1953), p. 230; Staff Presentation, “Strategic Area of the Philippines and the East Indian 

Islands,” p. 8. 

69 The Tawi-Tawi Group consists of the islands of 

Bonagoa, Manuk Mankaw, Simunul, Sanga-Sanga, 

and Tawi-Tawi.

70 Staff Presentation, “Strategic Area of the Philippines 

and the East Indian Islands,” pp. 10, 29–30.

71 Morison, New Guinea and the Marianas, p. 217.

72 Building the Navy’s Bases in World War II: History of 

the Bureau of Yards and Docks and the Civil Engineer 

Corps 1940–1946, vol. 2, part 3, The Advance Bases

(Washington, D.C.: GPO, 1947), pp. 317–18, available at www.history.navy.mil/.

73 Ibid., p. 320.

74 Ibid., p. 322.

75 Ibid., p. 325; Staff Presentation, “Strategic Area of 

Islands of the Central Pacific,” p. 19. 

76 Philip A. Crowl and Edmund G. Love, United States 

Army in World War II: War in the Pacific—Seizure of 

the Gilberts and Marshalls (Washington, D.C.: U.S. 

Army Center of Military History, 1993), p. 5.

77 Ibid.

78 Rottman, World War II Pacific Island Guide, 

p. 322.

79 Crowl and Love, Seizure of the Gilberts and Marshalls, p. 5.

80 U.S. Strategic Bombing Survey (Pacific), Naval Analysis Division [hereafter USSBS], The Campaigns of 

the Pacific War (Washington, D.C.: GPO, 1946), 

p. 234.

81 Commander in Chief Pacific Fleet [CINCPAC] 

Estab. Marshall Is. Sub-Area, ser. 00039, 4 April 44, 

p. 1, CINCPAC February 44 to April 44, box 26, 

RG 38, Records of the Office of the Chief of Naval 

Operations, Records Relating to Naval Activity 

during World War II, Plans, Orders and Related 

Documents, NARA.

82 Edward T. Buckley, Jr., Saipan and Joint Operations

(Carlisle, Pa.: U.S. Army War College, February 

1990), p. 19.

83 USSBS, Japanese Military and Naval Intelligence 

Division, Japanese Intelligence Section G-2 (Washington, D.C.: GPO, 1946), p. 4.

84 “Central Command Organization,” statement by 

ex-Capt. Toshikazu Ohmae to Capt. S. E. Morison, 

USN, Tokyo, March 1950, folder G-8, box 9, RG 

23, Battle Evaluation Group [hereafter BEG], NHC 

NWC; Morton, Strategy and Command, p. 234; David C. Evans and Mark R. Peattie, Kaigun: Strategy, 

Tactics, and Technology in the Imperial Japanese 

Navy, 1887–1941 (Annapolis, Md.: Naval Institute 

Press, 1997), p. 458; USSBS, Japanese Military and 

Naval Intelligence Division, Japanese Intelligence Section G-2, p. 4.

85 USSBS, Japanese Military and Naval Intelligence 

Division, Japanese Intelligence Section G-2, p. 4; 

“Japanese War Planning,” interrogation of Admiral 

Mitsumasu Yonai, Interrogation NAV No. 76, 17 

November 1945, in USSBS, Interrogations of Japanese Officials (Washington, D.C.: GPO, 1946), vol. 2, 

 p. 328; Morton, Strategy and Command, pp. 234–35; 

“Central Command Organization.”

86 Morton, Strategy and Command, p. 237.

87 “Japanese War Planning,” p. 330. 

88 Ibid., p. 239; Bates et al., Battle for Leyte Gulf, 

p. 149.

89 Morton, Strategy and Command, p. 239.

90 “Background of Leyte Battle, Philippine Area Naval 

Operations, Part II,” October–December 1944, p. 15, 

folder G-27, box 9, RG 23, BEG, NHC NWC; Bates 

et al., Battle for Leyte Gulf, p. 209, plate 12 facing 

p. 210.

91 COMINCH Summaries of Radio Intelligence 

Japanese Naval Activities (1 January 1944–31 

March 1944), p. 1414, SRNS 628-SRNS 0718 (pp. 

1290–1486), entry A1 9015, Summaries of Radio 

Intelligence Japanese Naval Attaché Messages 

(Japanese Naval Radio Intelligence Summaries, 

1942–1946), container 2, SRNS 353-718, RG 457, 

National Security Agency / Central Security Service, 

NARA [hereafter COMINCH Summaries of Radio 

Intelligence, 1 January 1944–31 March 1944].

92 The A-Go Operation, May–June 1944, Japanese 

Monograph No. 90 (Tokyo: Foreign Histories Division, General Headquarters Far East Command, 

1950), pp. 2, 17.

93 USSBS, Campaigns of the Pacific War, p. 236.

94 Ibid.

95 Crowl, Campaign in the Marianas, pp. 56–57.

96 Rottman, World War II Pacific Island Guide, p. 371.

97 Ibid., p. 375.

98 COMINCH Summaries of Radio Intelligence Japanese Naval Activities (1 April 1944–30 June 1944), 

p. 1512, SRNS 0719-SRNS 0809 (pp. 1487–1710), 

entry A1 9015, Summaries of Radio Intelligence 

Japanese Naval Attaché Messages (Japanese Naval 

Radio Intelligence Summaries, 1942–1946), container 3, SRNS 719–1083, RG 457, National Security 

Agency / Central Security Service, NARA [hereafter 

COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944].

99 USSBS, Campaigns of the Pacific War, p. 236.

100 Crowl, Campaign in the Marianas, p. 57.

101 Submarine Operations in the Third Phase Operations, Japanese Monograph No. 184, parts 3, 4, and 

5 (Washington, D.C.: Department of the Army, 

General Headquarters Far East Command, Foreign 

Histories Division, 1950), p. 18.

102 Adm. Harry W. Hill comments on E. B. Potter, 

“The Command Personality: Some American 

Naval Officers of World War II,” in Command and 

Commanders in Modern Warfare: The Proceedings 

of the Second Military History Symposium, U.S. Air 

Force Academy, 2–3 May 1968, ed. William Giffin 

(Washington, D.C. / Colorado Springs, Colo.: Office 

of Air Force History, Headquarters U.S. Air Force / 

U.S. Air Force Academy, 1971), p. 235.

103 Richard P. Harrison, Fleet Admiral Chester W. 

Nimitz: The Right Man for the Times (Toronto: Advanced Military Studies Course 2, Canadian Forces 

College, December 1999), p. 7; Thomas B. Buell, The 
J

Quiet Warrior: A Biography of Admiral Raymond 

A. Spruance (Annapolis, Md.: Naval Institute Press, 

1988), p. 173.

104 Cited in Harrison, Fleet Admiral Chester W. Nimitz, 

p. 8.

105 E. B. Potter, “Command Personality: Some American Naval Officers of World War II,” in Command 

and Commanders in Modern Warfare, ed. Griffin, 

p. 214.

106 Hill, comments on “Command Personality,” 

p. 237.

107 Morison, New Guinea and the Marianas, p. 235.

108 Hill, comments on “Command Personality,” 

p. 236.

109 Morison, New Guinea and the Marianas, p. 236.

110 Buell, Quiet Warrior, p. xxx.

111 Theodore Taylor, The Magnificent Mitscher (New 

York: W. W. Norton, 1954), p. 98.

112 Morison, New Guinea and the Marianas, p. 236.

113 Barrett Tillman, Clash of the Carriers: The True Story 

of the Marianas Turkey Shoot of World War II (New 

York: New American Library, 2005), pp. 18–19.

114 John Prados, Combined Fleet Decoded: The Secret 

History of American Intelligence and the Japanese 

Navy in World War II (New York: Random House, 

1995), p. 555.

115 A-Go Operation, p. 19.

116 USSBS, Interrogations of Japanese Officials, vol. 2, 

p. 573; Hiroyki Agawa, The Reluctant Admiral: 

Yamamoto and the Imperial Navy, trans. John Bester 

(Tokyo: Kodansha America, 2000; first published 

1969), pp. 11–12, 129.

117 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, pp. 1572–73.

118 Tillman, Clash of the Carriers, p. 37.

119 Ibid., p. 27.

120 COMINCH Summaries of Radio Intelligence, 1 

January 1944–31 March 1944, p. 1481.

121 Tillman, Clash of the Carriers, pp. 227–28.

122 Robert J. Cressman, The Official Chronology of the 

U.S. Navy in World War II (Washington, D.C.: Contemporary History Branch, Naval Historical Center, 

1999), p. 437.

123 Ibid., p. 439.

124 Cole, “Struggle for the Marianas,” p. 90. TF 58 

planes sank one light cruiser, two destroyers, one 

auxiliary cruiser, one auxiliary submarine depot 

ship, one aircraft ferry, seventeen transports, four 

fleet tankers, one water carrier, one auxiliary vessel, 

one army cargo ship, one merchant cargo ship, and 

one motor torpedo boat. They inflicted damage on 

two destroyers, two submarines, one target ship, a 

repair ship, an ammunition ship, a seaplane tender, 

and one auxiliary submarine chaser; Cressman, Official Chronology of the U.S. Navy in World War II,

p. 446.

125 Crowl, Campaign in the Marianas, p. 15.

126 Cressman, Official Chronology of the U.S. Navy in 

World War II, p. 447.

127 Cited in Mark D. Tate, Operation Forager: Air Power 

in the Campaign for Saipan (Fort Leavenworth, 

Kans.: School of Advanced Military Studies, U.S. 

Army Combined Arms Center, 2 June 1995), p. 23.

128 Cressman, Official Chronology of the U.S. Navy in 

World War II, p. 449.

129 Ibid., p. 456.

130 Submarine Operations in the Third Phase Operations,

pp. 7–8. 

131 USSBS, Campaigns of the Pacific War, p. 207.

132 They sank one destroyer, one repair ship, five fleet 

tankers, one sub chaser, four auxiliary submarine 

chasers, a patrol boat, a net layer, an aircraft ferry, 

five transports, two tankers, two guard boats, one 

salvage vessel, one torpedo transport/repair ship, 

five army cargo ships, and one army tanker, plus 

ten small craft at Angaur; they also damaged one 

submarine chaser, one net layer, one tanker, and 

one army cargo ship at Palau. Cressman, Official 

Chronology of the U.S. Navy in World War II, p. 465.

133 USSBS, Campaigns of the Pacific War, p. 207.

134 Cressman, Official Chronology of the U.S. Navy in 

World War II, p. 473.

135 Ibid., p. 476.

136 USSBS, Campaigns of the Pacific War, pp. 208–209.

137 Cressman, Official Chronology of the U.S. Navy in 

World War II, pp. 477–78.

138 Ibid., p. 482.

139 USSBS, Campaigns of the Pacific War, p. 209.

140 COMINCH Summaries of Radio Intelligence, 1 

January 1944–31 March 1944, p. 1290.

141 Ibid., p. 1335.

142 Ibid., pp. 1400–1401.

143 Joint Intelligence Center Pacific Ocean Area 

[JICPOA]–CINCPAC Intelligence Bulletins, 1 January–15 March 1944, p. 1, folder 3222/23, box 108, 

JICPOA-CINCPOA Bulletins 1 December 1942–30 

June 1944, RG 38, Records of the Office of the Chief 

of Naval Operations, Records of Naval Security 

Group Central Depository Crane Indiana, Inactive 

Stations NARA.

144 Ibid., pp. 1–2.

145 COMINCH Summaries of Radio Intelligence, 1 

January 1944–31 March 1944, p. 1469.

146 Ibid., p. 1470.

147 Ibid., p. 1476.

148 Ibid., p. 1470.

149 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, pp. 1607–608.

150 Morison, New Guinea and the Marianas, p. 214.

151 COMINCH Summaries of Radio Intelligence, 1 

January 1944–31 March 1944, p. 1484.

152 Ibid.

153 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1490.

154 JICPOA-CINCPAC Intelligence Bulletins, 16 

March–9 May 1944, p. 1, folder 3222/23, box 108, 

JICPOA-CINCPOA Bulletins 1 December 1942–30 
J()

June 1944, RG 38, Records of the Office of the 

Chief of Naval Operations, Records of Naval Security Group Central Depository Crane Indiana, Inactive Stations, NARA [hereafter JICPOA-CINCPAC 

Intelligence Bulletins, 16 March–9 May 1944].

155 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1495.

156 Ibid., pp. 1497–98.

157 JICPOA-CINCPAC Intelligence Bulletins, 16 

March–9 May 1944, p. 1.

158 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1502.

159 JICPOA-CINCPAC Intelligence Bulletins, 16 

March–9 May 1944, p. 1.

160 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1504.

161 A-Go Operation, p. 19.

162 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1505.

163 Ibid.

164 JICPOA-CINCPAC Intelligence Bulletins, 16 

March–9 May 1944, p. 1.

165 Ibid.

166 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1507.

167 Ibid., p. 1519.

168 Ibid., p. 1523.

169 JICPOA-CINCPAC Intelligence Bulletins, 16 

March–9 May 1944, p. 1.

170 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1559.

171 JICPOA-CINCPAC Intelligence Bulletins, 16 

March–9 May 1944, pp. 1–2.

172 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1564.

173 Ibid., p. 1581.

174 Ibid., p. 1583. 

175 JICPOA-CINCPAC Intelligence Bulletins, 16 

March–9 May 1944, pp. 1–2.

176 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 2, folder 3222/23, box 108, 

JICPOA-CINCPOA Bulletins 1 December 1942–30 

June 1944, RG 38, Records of the Office of the Chief 

of Naval Operations, Records of Naval Security 

Group Central Depository Crane Indiana, Inactive 

Stations, NARA [hereafter JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944].

177 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1589.

178 Ibid., p. 1590.

179 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 1.

180 Ibid., pp. 1–2.

181 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1600.

182 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 1.

183 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1606.

184 Ibid., pp. 1607–608.

185 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 1.

186 Ibid., p. 2.

187 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1617.

188 JICPOA Weekly Location Report (Japanese Fleet, 

Air Forces, Ground Forces), May–June 1944, part 

II, Air Forces, Area Distribution, 22 May 1944, pp. 

4, 181, Weekly Location Report, entry A1 9024, 

container 6, SRMD 16, parts 8–10, RG 457, National 

Security Agency / Central Security Service, Intelligence Reports from U.S. Joint Services and Other 

Government Agencies, December 1941–October 

1948, NARA [hereafter JICPOA Weekly Location 

Report, with date].

189 Ibid., pp. 5, 182.

190 A-Go Operation, p. 62.

191 JICPOA Weekly Location Report, 22 May 1944, pp. 

5, 182.

192 A-Go Operation, p. 7.

193 JICPOA Weekly Location Report, 22 May 1944, pp. 

6, 183.

194 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, pp. 1–2.

195 JICPOA Weekly Location Report, 29 May 1944, pp. 

1, 235.

196 Ibid., pp. 4, 238.

197 JICPOA, “Estimate of Enemy Distribution and 

Intentions, April 1943–July 1944,” p. 283, entry A1 

9024, container 3, SRMD 8–11, RG 457, National 

Security Agency / Central Security Service, Intelligence Reports from U.S. Joint Services and Other 

Government Agencies, December 1941–October 

1948, NARA.

198 Greg Bradscher, “The ‘Z Plan’ Story: Japan’s 1944 

Naval Battle Strategy Drifts into U.S. Hands,” Prologue 37, no. 3 (Fall 2005), p. 3, available at www

.archives.gov/.

199 Ibid., p. 2.

200 Ibid., p. 3.

201Ibid. 

202 Prados, Combined Fleet Decoded, pp. 550–51.

203 Ibid., p. 551.

204 JICPOA, “Estimate of Enemy Distribution and 

Intentions,” p. 285.

205 Ibid., p. 286.

206 JICPOA Weekly Location Report, 29 May 1944, pp. 

4, 238.

207 JICPOA, “Estimate of Enemy Distribution and 

Intentions,” p. 286.

208 JICPOA Weekly Location Report, 29 May 1944, pp. 

3, 237. 

209 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 1.

210 Ibid.

IV Japanese A-Go Operation (Battle of the 

Philippine Sea), 13–22 June 1944

Planning and Preparation

The U.S. plans for the invasions of the Marianas (Operation FORAGER) were a 

part of Nimitz’s campaign plan GRANITE II. Operation Plan (OPLAN) 3-44 

was issued by Admiral Nimitz on 23 April 1944. 

Allied Plans

The objectives in the southern Marianas were stated as follows: establish a base 

for operations against Japanese sea communications and for long-range air attacks 

against Japan; secure control of sea communications through the Central Pacific; 

and initiate the isolation and neutralization of the central Carolines. In the OPLAN 

Nimitz gave missions to his major subordinate commanders. Admiral Spruance 

was directed to “capture, occupy, and defend Saipan, Tinian, and Guam, and develop bases in those islands, and gain control of the remaining Marianas.” Perhaps 

surprisingly Nimitz did not mention the Japanese fleet. Halsey’s Third Fleet was 

directed to support operations of the Fifth Fleet units by air reconnaissance and attacks on enemy bases. Lockwood’s Task Force (TF) 11 would destroy enemy naval 

forces and shipping, perform observation and life-guard services off Truk, Woleai, 

and Palau, and intercept and destroy enemy forces approaching the Marianas or 

retiring from the assault area. D-day for Operation FORAGER was 15 June (the eastlongitude date). OPLAN 3-44 became effective on 1 May 1944.1

 On its basis, all 

major subordinate commanders developed their own operation plans.

Spruance’s OPLAN 10-44 of 12 May 1944 specified that the Fifth Fleet’s mission 

was 

to capture, occupy and place in a state of defense Saipan, Tinian and Guam; drive off or 

destroy enemy forces attempting to interfere with the movement to or the landing operations at each objective; direct the operations of aircraft of the Joint Expeditionary Force 

and those of Fast Carrier Task Forces, Pacific designated for air support of landings; initiate 

the construction of airfields, the improvement of harbors and the establishment of military 

government, withdraw troops not required for garrison duties, and naval forces not required 

for defense or covering operations as the situation permits, and in accordance with directive 

issued separately.2

Spruance’s plan was based on several assumptions. First, the planners assumed 

that Saipan, Tinian, and Guam were strongly protected and that the enemy would 
J

defend them vigorously. The Japanese would employ long-range aircraft from the 

Carolines, Iwo Jima, and Chichi Jima to attack U.S. forces in the southern Marianas. It was further assumed air strikes by the Allied aircraft based in the Marshalls 

and in the South and Southwest Pacific area against the Japanese air bases in the 

Carolines prior to and during FORAGER would prevent serious interference with 

U.S. forces in the southern Marianas. It was thought possible that enemy naval 

forces and carrier-based aircraft would try to prevent the capture of the southern 

Marianas or interfere with the unloading of materiel and personnel after the United 

States had accomplished its amphibious objectives.3

Spruance specified that the mission of the Fast Carrier Task Forces, Pacific 

would be “to prevent interference by enemy air action with the capture of Saipan, 

Tinian and Guam; protect the Joint Expeditionary Force and island positions 

after occupation by our landing forces from attack by enemy surface forces.” 

TF 58’s task groups (TGs), each screened by fast battleships in close tactical support, would destroy enemy aircraft and air facilities on Saipan, Tinian, Guam, 

Rota, and Pagan commencing three days before D-day—that is, D–3. On D–2, 

after the enemy’s ability to use airfields in the Marianas had been eliminated, TF 

58 would destroy defenses on Saipan, Tinian, and Guam. It would also destroy 

aircraft and air facilities on, and shipping present at, Iwo Jima and Chichi Jima.4

Mitscher, Commander, Task Force (CTF) 58, was given latitude to make changes 

in the employment of his forces due to weather conditions, enemy action, and 

other circumstances to accomplish the tasks prescribed.5

After the bombardment of the enemy positions had been completed, Mitscher 

would transfer Destroyer Division (DesDiv) 12 plus one destroyer (Selfridge) from 

TG 58.2 and Destroyer Squadron (DesRon) 1 from TG 58.3 to the Joint Expeditionary Force (TF 51), at a location to be designated by Admiral Turner. Mitscher 

was also directed to provide, beginning on D–1 and as requested by Turner, 

air support to troops on Saipan, Tinian, and Guam.6

 Spruance stipulated that TG 

58.1 and TG 58.4 would be released from operations against the Marianas in time 

to allow their refueling and replenishment of aircraft on D–1 in Area DOHENY.

7

OPLAN 10-44 specified that Commander, Forward Area, Central Pacific 

would, in coordination with South Pacific and Southwest Pacific forces, deny 

to the enemy the use of air bases at Truk; maintain the neutralization of Wake, 

Wotje, Taroa, Mille, Jaluit, Nauru, Kusaie, and Ponape; and maintain daily air 

searches in accordance with plans prescribed in its annex F. He was also tasked 

to “attack enemy ships and shipping; defend our bases in the Gilberts and Marshalls and provide air transportation.” CTF 57 would, when directed by Spruance, 

move two squadrons of patrol planes, with a tender, to Guam or Saipan and start 

searches from there. Also, when directed, he would move units of Service Squadron 12 to the Marianas and start developing harbors there. CTF 57 was also made 
J()

responsible for supporting of Central Pacific task forces at the Majuro, Kwajalein, 

and Eniwetok lagoons.8

Spruance’s plan stated that the Third Fleet and the Southwest Pacific Area would 

support operations of Central Pacific task forces by air search and air attacks on 

bases. Commander, Service Forces, U.S. Pacific Fleet; Commander, Air Forces, 

U.S. Pacific Fleet; Commanding General, V Amphibious Corps; and Commanding 

General, Central Pacific Area would also support the Central Pacific task forces.9

Spruance’s OPLAN 10-44 stipulated that D-day would be the initial landing on 

Saipan, W-day the landing on Guam, J-day the initial landings on Tinian, and Mday the initial day of as-yet-unscheduled landings against the “objectives not now 

designated.”10

TF 58’s plan specified that the fast carrier forces would on D–3 (12 June) initiate air strikes on Saipan, Tinian, Guam, Rota, and Pagan; destroy aircraft operating 

facilities, antiaircraft (AA) batteries, and coastal defenses; and burn cane fields in 

Saipan and northern Tinian that might offer concealment.11 On D–2 (13 June), 

TF 58 would continue strikes against Saipan, Tinian, Guam, Rota, and Pagan to 

prevent their airfields from operating. After obtaining control of the air over the 

Marianas, TF 58 would destroy defenses on Saipan, Tinian, and Guam and provide 

cover and support to minesweepers operating off Saipan. Battleships of TG 58.2 

and TG 58.3 escorted by DesDiv 12 (plus Selfridge) and DesRon 1 would destroy 

defenses on Saipan and Tinian and cover minesweeping operations. The battleships would operate beyond the effective range of the enemy’s coastal batteries and 

outside minable waters until they had been swept. Bombardment by the battleships 

in support of minesweeping and harassing fires by destroyers during the night of 

D–3/D–2 (12/13 June) would be as required by CTF 51. Support of minesweeping 

operations by carrier aircraft would be coordinated by Commander, Advance Support Aircraft, Joint Expeditionary Force.12

TF 58’s plan envisaged that on D–1 (14 June), TF 58 would maintain control 

of the air in the Marianas and provide air support for Saipan and Tinian, as requested by CTF 51. Air support would be coordinated by Commander, Advance 

Support Aircraft, Joint Expeditionary Force, embarked on the battleship Tennessee.

Commencing on D-1, the escort carriers of TF 51 would provide combat air patrol 

(CAP), antisubmarine patrol, smoke markers, aircraft to drop packages, observer 

aircraft, and artillery-spotting aircraft as well as, within their capabilities, photographic missions. TGs 58.1 and 58.4 would refuel and proceed to strike Iwo Jima 

and Chichi Jima. Commander, Battleships, U.S. Pacific Fleet would direct DesDiv 

12 (plus Selfridge) to report to Commander, Bombardment Group 1 on the morning of D–1 west of Saipan and at a distance of ten miles from that group. DesRon 

1 would be released from TG 58.2 and 58.3 in time to proceed to Point RICHFIELD

and rendezvous with Task Units (TUs) 16.7.3 and 16.7.4 at 0800 on D-day. DesRon 
J

1 would refuel and, at a suitable time after refueling, proceed to a position bearing 

085°, distance 120 miles from Point RICHFIELD and rendezvous there with TG 53.1 

at 0800 (in the minus-ten time zone) for duty with TF 53.13

On D-day, TGs 58.2 and 58.3 would maintain control of the air over the Marianas and provide air support for landing operations as requested by Commander, 

Advance Support Aircraft, Joint Expeditionary Force on board the amphibious 

command ship Rocky Mount (AGC 3). On D+1 (16 June) and D+2 (17 June), TGs 

58.1 and 58.4 would conduct strikes on Iwo Jima and Chichi Jima. Afterward, TG 

58.1 would receive replacement aircraft from TG 58.4 and then, accompanied by 

TU 58.4.1—consisting of Cruiser Division (CruDiv) 11 (two AA light cruisers), 

CruDiv 14 (three light cruisers), and DesRon 12 (eight destroyers)—proceed to 

Area SHELL for refueling.14

After D-day, TGs 58.2 and 58.3 would maintain control of the air and provide air support as required at Saipan and Guam. TG 58.2 would refuel at Point 

RICHFIELD on D+1 and TG 58.3 at Point COLLAR on D+2. Each group would replace aircraft while refueling. TG 58.1 would refuel in Area SHELL on the afternoon 

of D+4 (19 June). TU 58.4.1 would refuel from the same tanker group on D+5 (20 

June). TG 58.4 (three carriers) and DesRon 23 (six destroyers) would proceed to 

Eniwetok and arrive there on D+6 (21 June).15 There they would refuel, take on 

provisions, replenish aircraft, ammunition, and bombs, and depart upon completion, about D+8 (23 June).16

Admiral Mitscher’s staff prepared two tactical plans, JOHNNY and JEEPERS. Plan 

JOHNNY pertained to pre-invasion strikes against various targets in the Marianas. 

It stipulated that daylight fighter sweeps would be conducted on D–4 by TGs 58.1, 

58.2, 58.3, and 58.4 from their position about 240 miles bearing 105° from Saipan 

(about 250 miles bearing 080° from Guam). All groups would start their strikes at 

about 1400. Each large carrier would launch sixteen fighters and each light carrier 

twelve; in addition, each task group would launch three torpedo or dive-bombers. 

TG 58.1 would attack Guam and Rota airfields; TG 58.2 would attack Tinian, with 

a focus on the Ushi field; TG 58.3 would attack the Aslito field on Saipan; and TG 

58.4 would attack the Marpi and Charan-Kanoa fields on Saipan.17 Plan JEEPERS

envisaged fighter sweeps over the Marianas on D–3. All task groups would launch 

fighter sweeps over the target areas by 0515. They would also launch CAP and antisubmarine patrol, so that flight decks would be clear of armed planes by dawn.18

The plan of the Expeditionary Troops and Landing Force (TF 56) stipulated that 

carrier-based aircraft of TF 58, the Northern Attack Force (TF 52), and the Southern Attack Force (TF 53) would support the assault, occupation, and consolidation 

of FORAGER objectives. TF 58 would conduct fighter sweeps against airfields on 

Saipan on D–2 and D–1.19 On D–2, beginning early in the morning, fast battleships 

and destroyers of TF 58 would destroy aircraft and render airfields temporarily 
J()

useless, destroy coast-defense and AA batteries, burn all unburned cane fields south 

of Mutcho Point and the village of Chatcha, destroy enemy defenses and personnel, 

and cover the minesweeping of the shelf west of Saipan.20

Admiral Lockwood, in his OPLAN 2-44 of 21 May 1944, directed TF 17 to support FORAGER by 

destroying enemy naval forces and shipping, maintaining observation and lifeguard services 

off Truk, Woleai and Palau, intercepting and destroying enemy forces approaching or withdrawing from the assault area, stationing lifeguard submarines as requested by commander 

TF 58 for carrier based strikes, and preliminary photographic reconnaissance of enemy 

islands and atolls concerned, as requested by Commander, Fifth Amphibious force.21

Lockwood directed eleven of TF 17’s submarines to cover the movements of Ozawa’s forces. Three submarines covered Tawi-Tawi; three were stationed north of 

Luzon, three south of Mindanao, one at the eastern entrance of San Bernardino 

Strait, and one at the entrance of Surigao Strait.22

Lockwood’s plan noted that submarine patrols during the past several months 

had been concentrated in the vicinity of the Marianas and along the approaches 

to the Mariana Islands from home waters, Truk, Palau, and the Philippines. Their 

mission had been to “weaken by attrition reinforcements of enemy troops and supplies being sent to that area.” These patrols would continue during FORAGER, except 

that submarines in the immediate vicinity of the Marianas would move away to 

clear the area for surface forces. Prior to and during FORAGER at least one submarine would be maintained off Truk, Woleai, and Palau for surveillance and lifeguard 

services.23 TF 58 had requested that lifeguard submarines be stationed off Saipan, 

Guam, Chichi Jima, and Iwo Jima on days when carrier air strikes were scheduled.24

An annex of Spruance’s OPLAN 10-44 provided a detailed weather forecast. It 

predicted an area of bad weather about three hundred miles wide around the Marshalls would increase to a width of a thousand miles over the Philippines. Squalls, 

thunderstorms, and heavy rain would be prevalent throughout the area, creating 

unfavorable flying conditions, although aircraft would be able to operate most of 

the time. Only if the equatorial front were reinforced by a subtropical front would 

a mass of heavy rain make flying impossible.25 The winds would be adequate for 

carriers to launch aircraft without excessive speed. A moderate easterly swell was 

expected but would not interfere with carrier operations.26

During the invasion period, the cloud base would be from a thousand to two 

thousand feet. Normally the clouds would be a few thousand feet thick, some extending up to ten thousand feet in the form of swelling cumuli when unstable, 

showery conditions were present. The four-to-six-tenths cloud cover over Saipan 

would often obscure targets and prevent accurate high-altitude bombing. However, 

conditions for low-altitude bombing would be excellent. The air operations would 

become more difficult when the rainy season started in July, because of frequent 

showers, many of them very heavy.27
J

For surface ships, winds on D-day would be from the east at from eight to fourteen knots. Maximum waves would be approximately four feet, two to three feet 

near the shore and within a few miles of the leeward side of the islands. Between 5° 

and 10° north, the wind and sea would allow refueling on either easterly or westerly 

courses; above 10° north, easterly courses would be required. No difficulty was anticipated for refueling in the open sea anywhere in the area of operations.28

Japanese Plans 

Operational planning in the Japanese army and the navy was conducted by the respective general staffs and major field commands. The Army General Staff (AGS) 

and Navy General Staff (NGS) were organized along similar lines; the army was the 

senior service, and, not surprisingly, its staff was larger than the navy’s. The staffs 

consisted of a number of departments or bureaus, of which the most important 

were the 1st, Operations; 2nd, Transportation; 3rd, Intelligence; and 4th, Communications. Within the NGS, operational planning was the responsibility of the 1st 

Section’s 1st Department while the naval intelligence planning was the responsibility of the 3rd Department. Radio intelligence was provided by the Special Section 

of the 4th Department.29

Operational plans were developed separately for each service in the 1st Bureau 

of its respective general staff.30 Plans for major operations prepared by the army 

or the navy were usually made without input from the other service. Often, armynavy disagreement over a joint operation would result in its delay or even abandonment. Even when an agreement was reached, the operation would normally 

be executed not by a joint commander but by service commanders. Unity of effort 

would be based on the pertinent Army-Navy Central Agreement.31 The most important plans involving naval forces normally originated within the NGS. Its chief 

closely cooperated with the navy minister prior to the adoption of any operational 

plan, but once an operation started the navy minister had no control over it, direct 

or indirect.32 Final plans were prepared after discussions between the Commander 

in Chief (CINC), Combined Fleet, and the chief of the NGS. Joint operations were 

discussed at the liaison conferences between the army and the navy, the most important ones at the Imperial General Headquarters (IGHQ) level. Agreement had 

to be reached with the AGS before a plan was submitted to the chief of the NGS for 

final approval. After a joint operation was agreed on, identical orders were issued 

by the NGS and AGS. If a joint plan involved other government agencies, the navy 

minister’s agreement had to be obtained. If a forthcoming operation exceeded the 

authority delegated by the effective imperial directive to the chief of the NGS, the 

plan was submitted through IGHQ to the emperor for approval. Finally, the plan 

was issued as an order of the NGS.33 It would then be elaborated in more detail by 

the numbered naval and air fleets, area fleets, and subordinate tactical commands.
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The Imperial Japanese Navy’s (IJN’s) planning for the defense of the Central 

Pacific started in August 1943. After the death of Admiral Yamamoto in April 1943, 

his replacement as CINC of the Combined Fleet, Admiral Koga, directed that all 

operations after 15 August 1943 would be designated “Third Phase Operations of 

the War.”34 A new policy formally adopted in September 1943 envisaged employment of the entire Combined Fleet against the U.S. Pacific Fleet to destroy it in “a 

single blow.”35 IGHQ planned this destruction of enemy forces in mid-1944, after 

the enemy launched attacks in the Central Pacific and the Philippine area.36

IGHQ, in its Directive No. 209 issued on 25 March 1944, outlined the IJN’s “operational policy” in the Third Phase Operations of the War. Among other things, 

it directed that the navy shift from the offensive to the defensive. The IJN’s objectives were destruction of enemy naval and air forces that penetrated into the East 

Asian waters, disruption of enemy shipping routes, and an all-out effort to secure 

Japanese victory in the war. Priority would be given to air operations, surprise attacks, interception within the effective range of the land-based aircraft, intensified 

warfare against enemy sea communications, defense and protection of transport 

ships, and air defense of the home islands.37 For the Combined Fleet the main effort would be in the southeast area. The majority of its surface strength would be 

concentrated in the “Inner South Seas Area.” Any attack by the U.S. Pacific Fleet 

would be countered with the entire strength of the Combined Fleet, in the Z operation (the plan of which would be compromised the next year as described in the 

previous chapter).

The original plan for the Z operation was drafted in August 1943 during the 

struggle for the control of the Solomons. It contemplated the movement of the 

main body of the Combined Fleet to fight a “decisive battle” against the U.S. Pacific 

Fleet. The principal base for the Combined Fleet would be Truk; its operating area 

would encompass the entire sea area from the Kurils through the Marshalls and 

the Gilberts to north of the Solomons. The operating area was divided into several 

“operational districts,” according to possible routes of enemy attack, and assembly 

areas for the Japanese main forces were designated. Normally, the main body and 

the battleship force would be within a hundred miles of the First Mobile Force. 

The Combined Fleet designated “interception zones” around each advanced 

base (mainly air bases), within “strategic areas” identified by IGHQ. Each interception zone was divided into first, second, and third zones of defense. Each base 

would have ground forces. Air bases would be about three hundred nautical miles 

apart. The bases in the third zone of defense were in the Carolines and Marianas. 

In the Inner South Seas Area, the principal advanced base was Truk. For the second 

zone of defense, the bases were Eniwetok, Kusaie, and Ponape, and for the first zone 

of defense the Marshalls, Gilberts, and Nauru and Ocean Islands. Eniwetok and 

Kwajalein were designated as fleet anchorages. The IJN’s objectives were defense 
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of the main surface transportation routes between the home islands and Southern 

Resources Area, and defense of the fleet anchorages.

The general plan for the Z operation comprised four subordinate plans, designated A, B, C, and D. Plan A envisaged employment of the First Mobile Force as 

a nucleus for surface strike operations. Plan B envisioned employment of carriers 

with part of their screens to conduct air and surface operations. The main body of 

surface forces would conduct a separate operation. Plan C, a variant of B, contemplated air strikes first by carriers, then Base Air Force aircraft. Plan D contemplated 

the employment of surface forces only.38 Plan Z attached several detailed tables, or 

matrices, listing various enemy options and possible reactions by Japanese forces. 

Plan Z envisaged concentration of the maximum strength of the Combined Fleet 

at the right time should the enemy fleet go on the offensive. The main operation 

would be conducted in the Central Pacific. Aircraft, submarines, and picketboats 

would be employed for early detection of the enemy. Japanese forces would be in 

a state of high combat preparedness from the Kurils and east of the home islands 

to South Sea Islands, the Marianas, the Carolines, and western New Guinea. Most 

Japanese air strength would be employed against the enemy carriers so as to secure 

control of the air prior to the main attack against transport convoys. The enemy 

landing forces were to be destroyed on the beaches. The planners also prepared 

plans for the movements of the Japanese carrier forces to their respective operating 

areas (designated A, C, and D), all beyond the range of the enemy reconnaissance 

aircraft, from which they were to “maneuver to strike the enemy in the flank.” 

The Japanese planners estimated that by the end of March 1944, Carrier Division (CarDiv) 1, with the 601st Air Group (eighty-one fighters, eighty-one bombers, fifty-four attack aircraft, and nine reconnaissance aircraft), would be fully capable of operating in daylight. About half of its reconnaissance aircraft would be 

able to take off and return to the carriers at night, and about half of all its aircraft 

would be capable of taking off and carrying out strike operations. All the fighters 

and about half the reconnaissance aircraft of CarDiv 3, with the 653rd Air Group 

(sixty-three fighters, twenty-seven attack aircraft), would be capable of operating 

from land bases. However, its attack aircraft would be unable to carry out strikes. 

CarDiv 2, with the 652nd Air Group (eighty-one fighters, thirty-six bombers, eighteen attack aircraft), would have low effective fighting strength. By the end of April, 

both CarDivs 1 and 3 would be capable of surface strike operations, though CarDiv 

2 would have difficulty in conducting attacks against surface ships. Upon the completion of training, the 601st Air Group on board CarDiv 1 would be deployed to 

the Philippines. The First Mobile Fleet would be deployed at Tawi-Tawi and Palau. 

All forces in the Lingga area would proceed to the Pacific in preparation for the 

start of the Z operation. However, the Japanese anticipated problems in concentrating all their forces in the southern Philippines, because of fuel shortages. CarDiv 1, 
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CruDiv 7, and DesRon 10 would assemble north of the Bonins. All forces deployed 

in home islands would concentrate in their respective areas.

The Z operation plan described in some detail a “basic policy in the conduct of 

operations.” The strategically most advantageous area would comprise the Marianas, the Carolines, and western New Guinea. Hence, full-scale operations were 

planned for these areas. In case of a full-scale operation in the Marianas–Carolines, 

CINC, Combined Fleet would control the First Mobile Fleet and the Fifth Base Air 

Force. For subsidiary or “feinting” operations, local area-defense forces would be 

primarily employed. Surface operations with the carrier forces as a nucleus in the 

Marcus and Wake areas would be conducted within the range of land-based aircraft. The planners also anticipated difficulty in the employment of carrier forces 

east of Honshū or in the northeast. The Japanese gave special emphasis to patrolling and searching for the enemy in the important parts of the Pacific; these tasks 

would be given primarily to land-based aircraft. They also planned to conduct air 

raids against the enemy anchorages in the Marshalls, as well as raids by two-man 

submarines and amphibious tanks.

In the conduct of air operations, the emphasis would be to detect enemy fleet 

and landing forces one day prior to any surprise attack in the Marianas, Truk–

Mereyon, or Palau areas. Transports would be the primary objective. If enemy carrier forces attempted to obtain air superiority before the arrival of transports, the 

objective would be to “render all carriers useless.” If the enemy carriers and transports arrived at the same time, the objective would be “full attack at the transport 

convoy.”

The Japanese estimated that their forces would be ready to engage the enemy 

fleet by mid-April 1944. They were confident that the fuel situation would be satisfactory and that Plan A could be executed. If the fuel situation were uncertain, 

Plan B would be executed. If the training levels of the two carrier divisions differed, 

their operations would be based partly on Plan A and partly on B. If training were 

inadequate to conduct a surface strike, and it was possible to achieve surprise, Plan 

C would be executed. If the training level were not sufficient by the end of March, 

air units would operate exclusively from land bases and in accordance with Plan D. 

Surface forces would cooperate in air attacks but would be generally employed at 

night, unless Japanese forces obtained air superiority, in which case surface forces 

would be employed with the carriers during daylight hours.

Plan Z envisaged that prior to a decisive battle, Japanese submarines would 

cease their attacks against shipping in the southern Pacific. Most would be redeployed to the Marshalls. If enemy attack were imminent, most large (I class) submarines would be deployed in distant areas, while land-based aircraft searched for 

the enemy forces. Small submarines (RO class) would be deployed generally three 

to four hundred miles from their bases. The primary targets for the submarines 
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would be transports, but some might be called on to cooperate with the air attacks 

by attacking, if in position to do so, enemy carrier forces or damaged ships. Should 

operations be conducted in the Marcus Island area, the Japanese planned to assign 

four boats in that vicinity.

If a decisive battle were to be fought in the Marianas–eastern Carolines, Combined Fleet Headquarters would be moved to Tinian or Saipan. Alternatively, it 

would be moved to Davao if a decisive battle were to be found in the western Carolines or western New Guinea. If that decisive battle were to take place in the northeast, headquarters would move to Chitose, on Hokkaidō.

Despite all the planning and preparation, Admiral Koga did not execute the Z 

operation when the U.S. forces actually invaded the Gilberts and Marshalls. The 

main reason was that the Japanese carrier force was at Singapore undergoing intensive training, in order to become ready to serve as a mobile force by the end of 

April.39 After Koga’s death, Admiral Toyoda slightly modified the plan for the Z 

operation and renamed it “A-Go.”40 He also transferred control of battleship force 

to Admiral Ozawa.41

By April 1944, the Japanese had decided that the defense line connecting the 

Marianas, Truk, and Biak must be held at all cost.42 The A-Go plan envisaged the 

employment of the First Mobile Force—First Air Fleet (carrier striking forces), the 

23rd, 26th, 22nd, and 61st Air Flotillas of the Base Air Force, plus the Advance 

Expeditionary Force (Sixth Fleet) (submarines)—in the pending decisive battle.43

In the employment of the First Mobile Force, the emphasis was on a daytime attack beyond the effective range of enemy carrier aircraft.44 Base air forces would 

conduct reconnaissance of Tulagi, Guadalcanal and its vicinity, the Admiralties, 

and the islands of Majuro, Kwajalein, and Eniwetok.45 Surprise attacks would be 

conducted against carrier striking forces and anchorages in the Marshalls (the

TATSUMAKI operation). Five large submarines capable of transporting amphibious 

tanks and launching torpedoes would be sent to the target area.46

The plan for the base air forces was developed on the assumption that at least 

a third of the enemy carrier force would have been destroyed prior to the decisive 

battle. The remnants would be destroyed in cooperation with the First Mobile Fleet. 

The Base Air Force would be organized into three attack groups, composed of several types of aircraft: the 1st Attack Group (Saipan, Tinian, Guam, and Truk); the 

2nd Attack Group (Palau, Yap, and Davao); and the 3rd Attack Group (northern 

Australia and Celebes areas).47 The Base Air Force would conduct reconnaissance 

of Tulagi and its vicinity, the Admiralties, and the islands of Majuro, Kwajalein, and 

Eniwetok.48

Japanese night-fighting doctrine issued in January 1944 called for effective reconnaissance on the open ocean in cooperation with land-based aircraft and submarines. The enemy, once detected, would be destroyed by all forces, focusing on 
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the flank. If suitable conditions existed, the enemy would be “encircled and annihilated at one blow.” The enemy’s most modern ships would be destroyed first. The 

purpose of night operations was given as the destruction of the enemy’s general 

support forces—that is, carriers, battleships, and large cruisers, in that order. However, in “intercept” operations (Yogaki Tai), the main attack might be directed first 

against transport groups, then their screening forces. Japanese destroyer squadrons 

would try to avoid screening forces and attack instead the enemy’s main force.49 The 

Japanese doctrine laid down six methods for the employment of cruiser divisions 

and destroyer squadrons.50

Success in night combat would depend mainly on the timely coordinated action of each unit and on the independent actions of each commanding officer. 

The key prerequisites for success would be achieving surprise, keeping an excellent lookout, taking advantage of weather and geographical conditions, and 

properly using direction finders, radars, and hydrophones. Battleships would 

also take part in night actions, taking advantage of their speed and firepower to 

destroy screening forces and cover and support the advance. Cruiser divisions 

would scout and, in combination with battleship divisions, destroy screening 

forces. They too would cover the advance of the destroyer squadrons. Carrier 

forces would not take part in night fighting except in good visibility. Likewise, 

submarines would not take part; they would be employed primarily for scouting, 

in favorable conditions.51 This night-fighting doctrine was revised by Standing 

Order No. 15 of 1 May 1944, which added two new combat methods but otherwise left the doctrine unchanged.52

The Japanese planned to employ their submarines for reconnaissance of “strategic points” and surprise attacks.53 Vice Adm. Takeo Takagi, commander of the 

Sixth Fleet (submarines), issued Operational Order No. 122 on 14 May. Among 

other things, it directed that one large (I class) submarine would be deployed 

between the Admiralties and Wewak, one large boat would be deployed east of 

the Marshalls, and another large boat would be used for transport from the home 

islands to Mille. Additionally, one small (RO) boat would be deployed about a 

hundred nautical miles northeast of Kwajalein; and another would patrol some 

hundred miles northeast of Eniwetok.54

The Opposing Forces 

Prior to the decisive encounter in the Philippine Sea, the U.S. Pacific Fleet possessed 

superiority in numbers and quality of ships and aircraft (see sidebars). It had more 

fast carriers (seven versus five) and light carriers (eight versus four).55 It possessed 

massive AA defenses. The CAP over U.S. carriers was radar directed;56 American 

fighter direction was superior to that of the Japanese carriers. TF 58 ships had far 

better radar and radio communications.57

Continued on page 223 
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Japanese Order of Battle, May 1942

Commander, First Mobile Force: Vice Adm. Jisaburō Ozawa (Flagship Carrier Taihō)

Force C (Van) 

(Vice Adm. Takeo Kurita, flagship heavy cruiser Atago)

CarDiv 3 (Rear Admiral Sueo Obayashi, flagship Chitose) 

Air Group 653, total 90 aircraft

Light Carrier Chitose (21 A6M5b Zeros, 3 B6N1 Jills, 6 B5N2 Kates)

Light Carrier Chiyoda (21 A6M5b’s, 3 B6N1s, 6 B5N2s)

Light Carrier Zuihō (21 A6M5b’s, 3 B6N1s, 6 B5N2s) 

BatDiv 1, Vice Adm. Matome Ugaki (2 BBs—Yamato, Musashi)

BatDiv 3, Vice Adm. Yoshio Suzuki (2 BBs—Haruna, Kongō)

CruDiv 4, Vice Admiral Kurita (4 CAs—Atago, Takao, Maya, Chokai)

Cruiser Squadron 7 (4 CAs—Kumano, Suzuya, Tone, Chikuma)

DesRon 2 (less DesDiv 27), Second Fleet (Rear Adm. Miko Hayakawa, flagship light cruiser Noshiro)

DesDiv 31 (3 DDs—Asashimo, Kishinami, Okinami)

DesDiv 32 (2 DDs—Tamanami, Fujinami)

Attached to Desron 2: 1 DD (Shimakaze)

DesDiv 17, DesRon 10, Third Fleet (1 DD—Hamakaze)

Force A

(Vice Admiral Ozawa, flagship Taihō)

CarDiv 1, Air Group 601, total 209 aircraft

Carrier Taihō (27 A6M5 Zeros, 23 D4Y1 Judys, 17 B6N1 Jills, 2 D4Y1c Judys) 

Carrier Shōkaku (26 A6M5a Zeros, 24 D4Y1s, 17 B6N1 Jills, 3 D4Y1c Judys) 

Carrier Zuikaku (27 A6M5a Zeros, 23 D4Y1 Judys, 17 B6N1 Jills, 3 D4Y1c Judys) 

CruDiv 5, Rear Adm. Shintiro Hashimoto (2 CAs—Myōkō, Haguro)

DesRon 10, Third Fleet (Rear Adm. Susumu Kimura, flagship light cruiser Yahagi)

DesDiv 10 (2 DDs—Asagumo, Tanikaze)

DesDiv 17 (2 DDs—Urakaze, Isokaze)

DesDiv 61 (4 DDs—Hatsuyuki, Wakatsuki, Akizuki, Shimotsuki)

Force B

(Rear Adm. Takaji Joshima)

CarDiv 2, Air Group 652, total 135 aircraft

Carrier Junyō (27 A6M5a Zeros, 6 B6N1 Jills, 9 D4Y1 Judys, 9 D3A2 Vals) 

Carrier Hiyō (27 A6M5a’s, 6 B6N1s, 18 D3A2s) 

Light Carrier Ryuho (27 A6M5a’s, 6 B6N1s) 

Battleship Squadron 1 (1 BB—Nagato)

Heavy Cruiser Mogami

DesDiv 4, DesRon 10, Third Fleet (3 DDs—Michishio, Nowaki, Yamagumo)

DesDiv 27, DesRon 2, Second Fleet (4 DDs—Shigure, Samidare, Hayashimo, Akishimo)

Supply Forces

1st Supply Force 

1 DD (Hibiki)

3 AOs (Nichiei Maru, Kokuyo Maru, Seiyo Maru)

DesDiv 21 (1 DD—Hatsushimo)

DesDiv 22, DesRon 3, Central Pacific Area Fleet (1 DD—Yunagi)

2nd Supply Force 

3 AOs (Genyo Maru, Azusa Maru, Senyo)

DesDiv 17, DesRon 10, Third Fleet (1 DD—Yukikaze)

DesDiv 30, DesRon 3, Eighth Fleet (1 DD—Uzuki)

3rd Supply Force

1 DD (Tsuga)

3 AOs (Hayasu, Kosen Maru, Sunosaki-Kosen Maru)
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Sixth Fleet (Submarines)

(Vice Adm. Takeo Takagi, headquarters on Saipan)

5 I-class SSs (I-5, I-10, I-38, I-41, I-184)

16 RO-class SSs (RO-36, RO-41, RO-42, RO-43, RO-44, RO-47, RO-68, RO-104, RO-106, RO-108, 

RO-112, RO-113, RO-114, RO-115, RO-116, RO-117)

Base Air Force

(Vice Adm. Kakuji Kakuta, headquarters on Tinian, total 1,290 aircraft)

61st Air Flotilla

121st Air Group (10 D4Y1 Judys, Tinian; 10 D4Y1s, Peleliu)

261st Air Group (80 A6M5 Zeros, Saipan)

263rd Air Group (80 A6M5s, Guam; 40 A6M5s, Yap)

265th Air Group (40 A6M5s, Peleliu; 15 A6M5b’s, Guam)

321st Air Group (15 J1N Irvings, Tinian)

343rd Air Group (40 N1K Georges, Tateyama)

521st Air Group (80 P1U Franceses, Guam; 40 P1Ys, Tinian)

523rd Air Group (40 D4Y1s, Tinian; 40 D4Y1s, Yap)

761st Air Group (40 G4M Bettys, Peleliu)

1021st Air Group (20 L2D Tabbys, Tinian)

22nd Air Flotilla

151st Air Group (20 D4Y1s, Harushima-Truk)

202nd Air Group (40 A6M5s, Harushima-Truk; 40 A6M5s, Mereyon)

251st Air Group (20 J1Ns, Takeshima)

253rd Air Group (80 A6M5s, Takeshima)

301st Air Group (40 J2M Jacks, Yokosuka)

503rd Air Group (40 D4Yis, Kadeshima)

551st Air Group (80 B6N1 Jills, Harushima-Truk)

755th Air Group (40 G4Ms, Guam)

26th Air Flotilla

201st Air Group (80 A6M5s, Davao)

501st Air Group (40 A6M5/D4Y1s, Lasang)

751st Air Group (40 G4Ms, Davao)

23rd Air Flotilla

153rd Air Group (60 A6M5/D4Y1s, Sorong)

732nd Air Group (40 G4Ms, Wasile)

753rd Air Group (40 G4Ms, Menado)

Sources: Morison, New Guinea and the Marianas, pp. 416–17; Y’Blood, Red Sun Setting, pp. 222–27; Dan Muir, “Order of 

Battle: The Battle of the Philippine Sea 19–20 June 1944,” NavWeaps, www.navweap.com/index_oob/_OOB_WWII

_Pacific/OOB_WWII_Philippine_Sea.htm. 

U.S. Order of Battle 

Fifth Fleet

(Adm. Raymond A. Spruance, flagship heavy cruiser Indianapolis)

TF 58, Fast Carrier Task Force

(Vice Adm. Marc A. Mitscher) 

TG 58.1, Rear Adm. Joseph J. Clark

Carrier Hornet (Air Group 2—33 SB2C-4C Helldivers, 36 F6F-3 Hellcats, 4 TBF-1Cs, 14 TBM-1C 

Avengers, 4 F6F-3Ns) 

Carrier Yorktown (Air Group 1—40 SB2C-4C Helldivers, 4 SBD-5 Dauntlesses, 41 F6F-3 Hellcats, 

1 TBF-1C, 16 TBM-1C Avengers, 4 F6F-3Ns) 

Light Carrier Belleau Wood (Air Group 24—26 F6F-3s, 3 TBF-1Cs, 6 TBM-1Cs) 

Light Carrier Bataan (Air Group 50—24 F6F-3s, 9 TBM-1Cs) 

3 CAs (Baltimore, Boston, Canberra)

1 CL (Oakland)

DesRon 46 (9 DDs—Izard, Charette, Conner, Bell, Burns, Boyd, Bradford, Brown, Cowell)
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TG 58.2, Rear Adm. A. E. Montgomery

Carrier Bunker Hill (Air Group 8—33 SB2C-4C Helldivers, 37 F6F-3 Hellcats, 13 TBF-1Cs, 5 TBM-1C 

Avengers, 4 F6F-3Ns) 

Carrier Wasp (Air Group 14—32 SB2C-4C Helldivers, 34 F6F-3 Hellcats, 15 TBF-1Cs, 3 TBF-1Ds, 

4 F6F-3Ns) 

Light Carrier Monterey (Air Group 28—21 F6F-3s, 8 TBM-1Cs) 

Light Carrier Cabot (Air Group 31—24 F6F-3s, 1 TBF-1C, 8 TBM-1Cs) 

4 CLs (Santa Fe, Mobile, Biloxi, San Juan)

DesRon 52 (8 DDs—Owen, Miller, The Sullivans, Stephen Potter, Tingey, Hickox, Lewis Hancock, 

Marshall)

TG 58.3, Rear Adm. John W. Reeves

Carrier Enterprise (Air Group 10—33 SBD-5s, 31 F6F-3 Hellcats, 9 TBF-1Cs, 5 TBM-1C Avengers, 

3 F4U-2 Corsairs) 

Carrier Lexington (Air Group 16—34 SBD-5s, 37 F6F-3 Hellcats, 17 TBF-1Cs, 1 TBM-1C Avenger, 

4 F6F-3Ns) 

Light Carrier San Jacinto (Air Group 51—24 F6F-3 Hellcats, 6 TBM-1Cs, 2 TBM-1Ds)

Light Carrier Princeton (Air Group 27—24 F6F-3s, 9 TBM-1Cs) 

1 CA (Indianapolis)

1 Antiaircraft Light Cruiser (Reno)

CruDiv 12 (3 CLs—Montpelier, Cleveland, Birmingham)

DesRon 50 (5 DDs—Clarence K. Bronson, Cotten, Dortch, Gatling, Healy)

DesDiv 100 (4 DDs—Caperton, Cogswell, Ingersoll, Knapp)

DesDiv 90 (4 DDs—Anthony, Wadsworth, Terry, Braine)

TG 58.4, Rear Adm. William K. Harrill

Carrier Essex (Air Group 15—36 SB2C-1Cs, 38 F6F-3 Hellcats, 15 TBF-1Cs, 5 TBM-1C Avengers, 

4 F6F-3Ns)

Light Carrier Langley (Air Group 10—23 F6F-3s, 7 TBF-1Cs, 2 TBM-1Cs) 

Light Carrier Cowpens (Air Group 25—23 F6F-3s, 3 TBF-1Cs, 6 TBM-1Cs) 

CruDiv 11 (4 CLs—San Diego, Vincennes, Houston, Miami)

13 DDs (Lansdowne, Lardner, McCalla, Lang, Sterett, Wilson, Case, Ellet, Charles Ausburne, 

Stanly, Converse, Spence, Thatcher)

DesRon 12 (1 DD—Case)

DesDiv 24 (3 DDs—Sterett, Wilson, Ellet)

DesRon 23 (3 DDs—Converse, Spence, Thatcher)

TG 58.7, Battle Line (Vice Adm. Willis A. Lee, flagship battleship Washington) 

BatDiv 6 (1 BB—Washington)

BatDiv 7 (2 BBs—Iowa, New Jersey)

BatDiv 8 (2 BBs—North Carolina, Indiana)

BatDiv 9 (2 BBs—South Dakota, Alabama)

CruDiv 6 (4 CAs—Wichita, Minneapolis, New Orleans, San Francisco)

DesDiv 12 (4 DDs—Mugford, Ralph Talbot, Patterson, Bagley)

DesDiv 89 (5 DDs—Halford, Guest, Bennett, Fullam, Hudson)

DesDiv 106 (4 DDs—Yarnall [radar picket], Stockham [radar picket], Twining, Monssen)

Tender-Based Air, Saipan, Marianas

Seaplane Tender Ballard (Patrol Squadron 16—5 PBM-5 Mariners)

Land-Based Air, Mokerang Field, Los Negros

Bombing Squadron 101 (12 PB4Y-1 Liberators)

TF 17, Patrol Submarines

(Vice Adm. Charles A. Lockwood)

(Operating in support of the Marianas operation)

Bonin Islands (6 SSs—Plunger, Archerfish, Swordfish, Pintado, Pilotfish, Tunny)

East and southeast of the Marianas (5 SSs—Albacore, Seawolf, Bang, Finback, Stingray)

Ulithi–Philippines (5 SSs—Flying Fish, Muskallunge, Seahorse, Pipefish, Cavalla)

Off the Surigao Strait (1 SS—Growler)

Other (2 SSs—Gar, Plaice)
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The Japanese were numerically grossly inferior in carrier-based aircraft (434 

versus 930). This figure included only 222 fighters, 113 dive-bombers, and ninetyfive torpedo bombers; the corresponding numbers for the United States were 475, 

232, and 184. The Japanese also had forty-three floatplanes, versus the Americans’ 

sixty-five.58 As for types, the Japanese had in service modern Mitsubishi A6M Type 

0 (Zero) fighters and fighter bombers, Yokosuka D4Y Suisei (Judy) torpedo bombers, Nakajima B6N Tenzan (Jill) attack aircraft, and Nakajima B5N (Kate) torpedo 

bombers.

By 1944, the U.S. Navy had in service several excellent carrier-based aircraft, 

such as the Grumman F6F-3 Hellcat (its night version was the F6F-3N) and the 

Vought F4U-2 Corsair fighter, the Curtiss SB2C-1C Helldiver dive-bomber, and 

the Grumman TBF-1/D/TBM-1C Avenger torpedo bomber. Also in service were 

older Douglas SBD-5 Dauntless dive-bombers. The U.S. carrier aircraft could 

search out to 350 miles (carrying extra gas in lieu of weapons), yet their effective 

striking range was only 150 to two hundred miles. 

Japanese aircraft had a much longer search range, some 560 miles, because they 

were not fitted, like their American counterparts, with self-sealing fuel tanks. Their 

attack range was about three hundred miles. The range of Japanese carrier aircraft 

could be increased if they refueled in the Marianas.59 Another major advantage 

for the Japanese was that easterly trade winds predominated in the operating area. 

This would allow Ozawa to approach the enemy carriers, closing the range, while 

launching and recovering aircraft.60 With some luck and skillful calculation he 

could stay outside the effective range of enemy carrier aircraft.61

Most of Ozawa’s carrier commanders were new to their ships, with only two or 

three months’ experience on board.62 Japanese pilots at this stage of the war were 

poorly trained. U.S. naval intelligence believed, from interrogation of the captured 

pilots, that they had only three to four hundred hours of flight time. A large proportion of captured Japanese pilots had been only a few months at most in the 

combat area.63 Actually, the Japanese pilots had much less flight time than they 

were credited with by U.S. intelligence; they were very young and inexperienced. 

For example, the air groups of CarDiv 1 had had only six months of training. None 

of the pilots in CarDiv 2 had more than a hundred hours of flying experience.64

The pilots of CarDiv 3 had three months of training. Very few Japanese aircraft had 

Seventh Fleet Submarines

(Rear Adm. Ralph W. Christie)

Southeast of Mindanao (3 SSs—Hake, Bashaw, Paddle)

Tawi-Tawi area (4 SSs—Harder, Haddo, Redfin, Bluefish)

Off Luzon (2 SSs—Jack, Flier)

Sources: Morison, New Guinea and the Marianas, pp. 412–16; Ministry of Defence (Navy), South-East Asia Operations and 

Central Pacific Advance, pp. 244–46. 
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radar, and the crews of those few were not properly trained in its use. Months spent 

at Tawi-Tawi were lost for training purposes because the fleet was kept mostly immobile to save fuel and avoid submarines.65 The air groups had very little experience in communications, and their radars were totally unusable.66 Their aircraft 

were frequently damaged; maintenance was poor and behind schedule. Prior to the 

sortie from Tawi-Tawi on 13 June, out of 120–130 aircraft sent as reinforcements 

from Yokosuka, some two-thirds of their pilots were still being trained when the 

A-Go operation started.67

In contrast, a pilot in the U.S. Navy had two years of training and three hundred hours of flying time before he was considered fit to fly from a carrier. Most 

of Mitscher’s pilots were combat veterans.68 The U.S. Navy’s method of training its 

pilots was also much more effective. After the battle of Midway in June 1942, the 

U.S. Navy recalled its best pilots to train new ones; in contrast, the Japanese kept 

their best pilots in frontline units until they were lost in combat, and hence their 

replacements were never properly trained. Nevertheless, U.S. naval intelligence at 

that time believed that first-line Japanese pilots were well trained, resourceful, and 

skillful in handling their aircraft. They were assessed as being aggressive, alert, and 

quick to take advantage of any evident weakness on the part of their American 

counterparts.69

The Japanese had available some 630 land-based naval aircraft.70 However, the 

actual effectiveness of the Base Air Force continuously decreased in the months 

preceding the U.S. invasion of the Marianas. This happened despite an increase in 

the numbers of frontline aircraft and an accelerated training program.71 The 23rd 

Air Flotilla suffered heavy losses. It was redeployed from the Netherlands East Indies (NEI) to the Central Pacific following the Allied strikes in February–March 

1944. Afterward, it lost many aircraft during the Biak Island operation, and then 

most of its aircraft were transferred to the Carolines.72 About half of both the 2nd 

and 3rd Attack Groups of the Base Air Force was lost at Biak (see sidebar for details 

of that operation) and while returning to A-Go. In addition, just before the decisive 

battle with TF 58, the 1st Attack Group suffered extensive losses from attacks by 

U.S. carrier aircraft against the Marianas, the Carolines, and Iwo Jima. Many crew 

members suffered from malaria, and facilities in the western Carolines were poor. 

As it turned out, only about 20 percent of the 1st Attack Group took part in the 

A-Go operation.73

The Japanese had a potential advantage against TF 58 in that the pending battle 

would take place within the effective range of land-based aircraft at Guam, Rota, 

and Yap. Ozawa counted on the use of two large and several small airfields in the 

Marianas. Theoretically, the Japanese could equalize strength in the air by using 

several hundred land-based aircraft in combination with their carrier aircraft. The 

A-Go operation plan placed five hundred planes at Yap, Palau, Guam, and Tinian in 
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Allied Landing on Biak and Japanese Reaction, 27 May–11 June 1944 

During the preparations for the A-Go operation, the Japanese were faced with a difficult decision—how 

to react to the Allied landing on Biak on 27 May 1944. Biak is the largest island (twenty miles by forty-five) 

in the Schouten group. It controls the entrance to Geelvink Bay (Cenderawasih Bay today), off the western 

tip of New Guinea. About a third of this foot-shaped island is covered by low, flat-topped hills; the rest is 

flatland with thick jungle. Bosnik, on the southeastern coast, was the administrative center. In 1944, some 

twenty-five thousand natives lived on the island.1 Although the Japanese high command anticipated an 

attack on Biak, it was surprised that the assault came so soon. Since 1943 Biak had been considered by the 

Japanese as one of the key points in their perimeter defense. However, on 9 May, IGHQ decided to move 

the defense line to Sorong and Halmahera, thereby leaving Biak as another strongpoint to be defended 

to the last man.2

Admiral Ugaki, Commander, Battleship Division (BatDiv) 1, was one of the strongest advocates of the 

absolute necessity to defend Biak. On 25 May he argued that the enemy could build several airfields there 

that would make it very difficult for the Japanese to operate aircraft in the western end of New Guinea. 

Also, Palau would be within striking range of enemy aircraft based on Biak, which would make it impossible for Japanese surface forces to operate east of Mindanao during the pending A-Go operation.3

On 27 May, TF 77 (Rear Adm. William M. Fechteler) landed the Hurricane Attack Force, the U.S. Army’s 

41st Division, on Biak (Operation HORLICKS). The 41st Division, with most of its equipment, was embarked 

at Humboldt Bay on Z–2 day (25 May). The entire force sailed the same evening, to be joined the next 

morning by a covering force, the heavy and light cruisers and destroyers of TG 77.2 (Rear Adm. Victor A. 

C. Crutchley, RN) and TG 77.3 (Rear Adm. Russell S. Berkey). Speed was limited to the 8.5-knot maximum 

of the tank landing ships. There was no chance that the Allied force would avoid being sighted by search 

aircraft. Allied estimates of Japanese troops on Biak were universally optimistic. It was believed that no 

more than two thousand Japanese troops were on the island. But in fact as of 27 May some ten thousand 

battle-hardened soldiers were there. The core defense was the highly trained 222nd Infantry Regiment.4

On 27 May, the Japanese deployed seventy carrier-based fighter planes, four land-based reconnaissance planes, and sixteen carrier-based bombers to western New Guinea. At the same time, Japanese 

aircraft based in the Sorong area attacked the enemy forces on Biak.5 One day later, the Naval General Staff 

directed 23rd Air Flotilla to be reinforced by fifty aircraft from Japan via the Philippines, along with twenty 

fighters and twenty bombers from the Marianas.6 Within several days the strength of the 23rd Air Flotilla 

was increased from sixteen to two hundred aircraft.7

On 29 May, the Southwest Area Fleet twice requested the Combined Fleet to counter the enemy landing on Biak.8

 Ugaki too had urged quick action, once it had become clear that invasion of Biak was imminent. Adm. Shirō Takasu, commander of the Southwest Area Fleet, recommended a counterlanding 

on Biak.Yet Ozawa wisely did not want to commit the entire First Mobile Fleet, because of expected high 

losses and the poor state of training of his pilots.9

On 29 May the Combined Fleet issued Order No. 102 directing subordinate forces to start preparations 

for a counterlanding on Biak. Combined Fleet’s plan was to transport part of the 2nd Sea Mobile Brigade at 

Zamboanga rapidly to Biak. The aim was to secure the island and seek an opportunity to induce the enemy 

to come out. The operation would be named KON (see map next page). On X-day (3 June) the invading 

force would penetrate into the Biak area. Forces would assemble at Davao on 31 May. CruDiv 16, under 

Rear Adm. Naomasu Sakonju, would be in command of the transport unit, composed of two CAs (Aoba 

1 Morison, New Guinea and the Marianas, pp. 103–104.

2 Ibid., p. 107.

3 Ugaki, Fading Victory, p. 376.

4 Morison, New Guinea and the Marianas, pp. 106–107.

5 A-Go Operation, p. 21; A-Go Operations Log: Supplement, p. 4.

6 Cited in Morison, New Guinea and the Marianas, p. 118.

7 Ibid., p. 122.

8 Ugaki, Fading Victory, p. 378.

9 Prados, Combined Fleet Decoded, pp. 555–56.
J

CELEBES BORNEO MIN

DAN

A

O

CERA

M

NEW

GUINEA

T wi a aT wi

VOGELKOP

M O L U C C A S E A

115° 125° 130°E 135° 120°

5°N

0°

Map 4: 

KON OPE

R

ATION: JA

PANESE N

AVAL M

OVEMEN

TS, 30 

M

a

y–11 June 1944

KONop102512AL

240 180 120 60 0

Nautical Miles

Legend

CruDiv 16, (AOBA, KINU, 3DDs)FUSO/DesDiv 10, (2 DDs)CruDiv 5/DesDiv 27, (

MYOKO, HAGURO, 3 DDs)

BatDiv 7/ DesRon 2, (YAMATO, MUSASHI, 5 DDs)6 DDs, Sorong to Biak B-9 June

0600

3 June

1100

3 June

2 June

31 

May

30 

May

10 June

2025

3 June

First

movement

cancelled

13 June

HARUSAME sunk by

B-24s, P-38s

1245

8 June Allied surface forces

sighted 2240

8 June

depart 30 

May

Batjan

Obimajor

Misool

BIAK

Waigeo

Amboina

Tarakan

Zamboanga

MAKASSAR STRAIT

Mendo

Sorong

A MLAH

HERA

Davao

KON Operation: Japanese Naval Movements, 30 May–11 June 1944
J()

and Kinu) and three DDs (Shikanami, Uranami, Itsukushima), a direct escort unit (CruDiv 5), and an indirect 

escort unit (Fusō and two DDs).10 The 23rd Air Flotilla would conduct preliminary strikes against enemy 

ships.11 However, on 30 May, Rear Admiral Itō had only eighteen aircraft available. He soon received the 

first of the planned 166 aircraft directed to be redeployed from the Marianas to Sorong, on the northwestern coast of the Vogelkop Peninsula (Dutch New Guinea).12

The Southwest Area Fleet would use barges for transporting troops from Sorong to Manokwari (the 

eastern part of the Vogelkop Peninsula) and then to Biak.13 The forces assigned to the A-Go operation 

would provide necessary support to KON while at the same time maintaining a high state of readiness for 

a decisive battle near the Marianas. Forces of direct screen and distant cover for the KON operation would 

return to their original units once the operation was completed.14

On 30 May, Commander in Chief, United States Fleet (COMINCH) analysts learned from radio intercepts that the chief of staff of Central Pacific Area Fleet had requested additional escort vessels to assist in 

transporting First Air Fleet personnel and material from Saipan to Palau, departing on 29 May. It was also 

learned from a Japanese army message sent on 5 May that the Japanese had deduced that Biak would be 

the target of the next enemy landing and urged speed in strengthening Biak and Manokwari. CruDiv 16 

(Aoba, Ōi, one DD) appeared to have completed successfully a transportation run to Sorong. The American 

analysts (erroneously) believed that the reinforcements of troops in western New Guinea by CruDiv 16 

were part of the A-Go operation.15 The COMINCH analysts also believed that enemy air units on Yap had 

been transferred to western New Guinea and would be replaced soon by other units. The Japanese reaction to the Biak operation seemed to be largely limited to air reinforcements of western New Guinea, with 

Sorong and Babo most prominent in traffic.16

On 30 May, the daily COMINCH intercept summaries assessed that the enemy’s intention was to counter the Allied landing to the east of Mokmer on the next day. The Japanese air units based at Babo (on the 

southern shore of McCluer Gulf), Wasile Bay (Halmahera), and Sorong had been requested to attack the 

assembly area of Allied destroyers. About forty-five Zero fighters flew from Peleliu to Wasile on 31 May. In 

addition, nineteen dive-bombers were scheduled to depart Peleliu for Babo on 1 June. A convoy of thirty 

ships escorted by one destroyer was scheduled to arrive to Sorong from Palau on 4 June.17

On 31 May, IGHQ directed the transfer of twenty bombers, eight reconnaissance planes, and fortyeight fighters from the Carolines to Sorong and Halmahera.18 In the morning the same day, eighteen twinengine bombers flew from Guam for Palau, while forty-five fighter aircraft departed Palau for Wasile Bay, 

and nineteen scouting aircraft flew from Palau to Babo.19 These aircraft were assigned to the 23rd Air Flotilla.

In the first Japanese attempt to send reinforcements to Biak (31 May–4 June), three destroyers of the 

KON unit, escorted by Sakonju’s heavy cruiser Aoba, fueled at Tarakan, where they embarked 1,700 troops 

for Zamboanga on 31 May. The KON unit continued to Davao, where it was joined by two heavy cruisers 

(Myōkō, Haguro) and three more destroyers. This part of the force departed before midnight on 2 June. The 

other eight hundred troops of the amphibious brigade were embarked at Zamboanga in a detached force 

consisting of two minelayers, one transport, and one tank landing ship. Escort by submarine chasers was 

provided for the run to Biak. The battleship Fusō and two DDs took a more northerly and evasive route.20

On 1 June, Joint Intelligence Center Pacific Ocean Area (JICPOA) learned that the Japanese were evaluating favorable landing points on Biak Island for a landing by the 2nd Mobile Marine Brigade. The date of 

10 A-Go Operation, p. 23.

11 Morison, New Guinea and the Marianas, p. 118; A-Go Operation, p. 23.

12 Morison, New Guinea and the Marianas, p. 119.

13 Ibid., p. 118; A-Go Operation, p. 23.

14 Ugaki, Fading Victory, p. 379.

15 COMINCH Summaries of Radio Intelligence Japanese Naval Activities, 1 April 1944–30 June 1944, pp. 1635–36.

16 Ibid., p. 1636.

17 Ibid., p. 1638.

18 Cited in Morison, New Guinea and the Marianas, p. 118.

19 JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944, p. 2.

20 Morison, New Guinea and the Marianas, pp. 119–20.
J

the landing was unknown but was believed to be “in the near future.”21 A message originated by Biak and 

addressed to CINC, Combined Fleet, CINC, Southwest Area Fleet, 4th Southern Expeditionary Fleet, and 

18th Guard Division (at Manokwari) indicated that the Korim Bay was considered a more suitable landing 

site than Wardo Village. The American analysts concluded that the Japanese reaction to the Biak operation 

was taking shape and that “present indications, while still somewhat vague, are that Japanese troops will 

be landed at Korim Bay and escorted by ships operating from Babo.” They also believed that one battleship

(Fusō), three heavy cruisers (Haguro, Myōkō, and Aoba), one light cruiser (Ōi), and several DDs would take 

part in the operation.22

On 1 June, the Japanese selected Wardo Village as the primary landing and Korim Bay as the secondary site. The Combined Fleet sent a message: “In view of the dauntless reconnaissance, communications 

intelligence and the war situation at Biak, the major part of the enemy task force seems to be coming to 

western Carolines and there is a good possibility of the first decisive battles taking place in the area of 

western Carolines on 2, 4, 5, and 6 June.” The screening and escort forces of the KON force would maneuver 

in such a way as to lure the enemy to the Palau area. Afterward, the main body would quickly advance to 

the east of the Philippines. In Ugaki’s view, Combined Fleet was getting nervous and was exaggerating 

things, because of its focus on communications intelligence. Combined Fleet was firmly convinced that 

the enemy would come to Palau. In Ugaki’s view, the greater the resistance the Japanese offered on Biak, 

the more likely an enemy diversion elsewhere would be. Ugaki believed (erroneously) that the enemy fleet 

would be concentrated in the area of the Vogelkop Peninsula.23

On 1 June, Rear Adm. Keizō Komura, chief of the staff of the First Mobile Force, told Admiral Kusaka, “In 

view of the great probability of the enemy throwing his task force against western New Guinea and Halmahera as a diversion to break the stalemate at Biak, it is necessary to expect a decisive battle in connection 

with the operation KON, in the vicinity of Point A [180 miles southwest of Palau]. In order to prepare to meet 

this probability it is necessary to prepare to concentrate most of other Fifth Base Air Force groups at an 

appropriate time, to be able to cooperate with the task force operation.” However, Ugaki believed that the 

area of possible decisive battle should have been extended as far as Helen Reef, two hundred miles north 

of Vogelkop Peninsula, rather than Point A. On 1 June the Combined Fleet directed the Fifth Base Air Force 

to concentrate the 2nd Attack Air Group in the western New Guinea and Halmahera areas. Advanced bases 

would be prepared at Sorong and Babo, with nearby bases at Wasile and Kau.24 The next day, shortly after 

midnight, the KON transport unit departed for Biak.25

On 1 June, JICPOA informed all fleet and task force commanders that sightings by U.S. submarines on 30 

and 31 June indicated movement of battleships and heavy cruisers in the Davao and Tawi-Tawi areas. Only 

CruDiv 16 (Aoba), CruDiv 5 (Haguro, Myōkō), and the battleship Fusō appeared associated with the western 

New Guinea area. They might be used for troop transportation from the southern Philippines and Palau to 

western New Guinea–Halmahera. Nimitz also reported that Japanese intelligence believed that there were 

considerable Allied surface forces in the Admiralties on 29 May. The next day, the same Japanese analysts 

assessed that the U.S. force might move northwestward and advised alerting Japanese forces.26

After the landing on Biak, Adm. Thomas C. Kinkaid (1888–1972), Commander, Allied Forces, Southwest 

Pacific Area (SWPA), deployed two cruiser groups (under Admiral Crutchley and Admiral Berkey) to cover 

alternately the northeastern approaches to the island. On 2 June, Admiral Kinkaid and his staff were convinced that the Japanese would approach Biak from the northeast. Accordingly, he recalled Crutchley’s 

cruiser group for refueling and replenishment to Humboldt Bay. He also put both cruiser groups under his 

own command and ordered this combined force to meet the Japanese.27

On 2 June, eight Allied tank landing ships arrived from Hollandia to Bosnik. By 1630 four of them had 

completed discharging. When Japanese aircraft carried out their strikes, there was no Allied air opposition, 

21 JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944, p. 1.

22 COMINCH Summaries of Radio Intelligence Japanese Naval Activities, 1 April 1944–30 June 1944, p. 1641.

23 Ugaki, Fading Victory, p. 383.

24 Ibid., pp. 384–85.

25 Morison, New Guinea and the Marianas, p. 119.

26 JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944, pp. 1–2.

27 Morison, New Guinea and the Marianas, p. 122.
J()

because the aircraft were grounded by bad weather at Wakde and Hollandia. The Japanese attack lasted 

for sixty-five minutes. The Allies suffered no losses except for a near miss of one landing ship. Out of fiftyfour aircraft, the Japanese lost twelve.28

That same day, at 2345, Crutchley’s force—four cruisers (Australia, Phoenix, Boise, and Nashville) and 

fourteen DDs (including two Australian)—departed Hollandia and steamed toward the enemy’s initial 

position. Crutchley was directed to destroy the enemy force reinforcing Biak but to withdraw if it proved 

superior in strength. If the enemy were not intercepted on 4–5 June, Crutchley was to retire toward Hollandia the next day.29

The next day, JICPOA informed fleet and task force commanders that Babo and Sorong would be the 

main air bases from which the enemy intended to launch torpedo and dive-bombing attacks against Allied forces on Biak.30 CruDiv 16 (Aoba and Kinu, plus two destroyers), it reported, would soon proceed to 

Biak, probably transporting the 2nd Mobile Marine Brigade. The landing would be made either between 

the Wardo River and a point 3.7 miles to the south or in the Korim Bay–Wardo Bay area. The time of the 

landing was estimated as between 2100 and 2300 on either 4 or 5 June.31

On 3 June, JICPOA decrypted messages revealing that the Japanese intelligence believed that a strong 

U.S. force would operate north of New Guinea. The intercepts also suggested that the Japanese believed 

that their forces had probably been discovered by the Allies. The American analysts believed that CruDiv 

16 was en route to Biak and that Fusō and CruDiv 5 were also in the area.32

Before noon on 3 June, B-24 Liberators from Wakde, operating on the basis of radio intercepts, sighted 

and shadowed the KON transport unit.33 The Japanese were surprised to be detected so early and so far 

from their ultimate destination; they had lost the element of surprise. The Japanese also had hoped to 

engage what they believed to be an enemy carrier force at Biak, plus other heavy forces, but that did not 

happen. All this led Toyoda to suspend the entire operation at 2035 on 3 June.34 Toyoda directed CruDiv 5 

and Fusō to return to their original units; the transport force would disembark troops at either Sorong or 

Manokwari and then withdraw to Ambon.35 Fusō, two heavy cruisers (Myōkō, Haguro), and two DDs would 

remain at Davao. At the entrance of Davao a U.S. submarine, Hake, sank one of the destroyers. Aoba, Kinu,

and six DDs, with units detached from other forces, proceeded to Sorong, where they disembarked troops 

on the evening of 4 June.36 There they were harassed by the Allied bombers of the Fifth Air Force. 

On 3 June, a group of Allied ships (three DDs, eight tank landing craft, and four infantry landing craft—

three of them with rockets and one carrying demolition parties) were off Bosnik, on the southeast coast 

of Biak. They were subjected to a second air attack, by thirty-two Zeros and nine heavy bombers of the 

23rd Air Flotilla, plus ten aircraft of the Fourth Air Army at Samate (on Salawati Island, west of Vogelkop 

Peninsula).37 This attack caused only slight damage to the Allied vessels, but out of forty-one aircraft the 

Japanese lost eleven.38

About noon on 4 June a Japanese search plane sighted Crutchley, with TFs 74 and 75, some 120 miles 

east of Biak. Shortly afterward, Admiral Itō sent twenty-eight fighters and six bombers to attack them. 

The lack of carriers to provide CAP made Crutchley’s force very vulnerable. In the attack two light cruisers

(Nashville, Phoenix) were slightly damaged by near misses.39 At 1900, Crutchley’s force reached its assigned 

position. Kinkaid advised Crutchley that if the Japanese tried to land, their landing site would be near 

Wardo.40

28 Ibid., p. 119.

29 Ibid., pp. 122–23.

30 JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944, p. 1.

31 Ibid.; COMINCH Summaries of Radio Intelligence Japanese Naval Activities, 1 April 1944–30 June 1944, p. 1646.

32 JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944, p. 1.

33 Morison, New Guinea and the Marianas, p. 120; Prados, Combined Fleet Decoded, p. 556.

34 Morison, New Guinea and the Marianas, p. 120.

35 Ugaki, Fading Victory, p. 387.

36 Morison, New Guinea and the Marianas, p. 120.

37 Cited in ibid.

38 Ibid., p. 122.

39 Cressman, Official Chronology of the U.S. Navy in World War II, p. 491.

40 Morison, New Guinea and the Marianas, p. 124.
J

A study on 5 June by COMINCH analysts of enemy radio traffic pertaining to the Biak operation strongly suggested that Fusō, CruDiv 5, and DesDiv 10 had been withdrawn as part, or in support, of CruDiv 16’s 

troop-transportation mission to New Guinea–Halmahera. These ships would be refueled and then would 

probably join the First Mobile Force, or sail to the east of Mindanao. Admiral Toyoda was in charge of the 

entire operation. The Japanese commander on Biak, COMINCH analysts reported, had requested that the 

3rd Air Attack Force strike a group of enemy ships composed of two heavy cruisers, ten destroyers, and 

eight transports, plus numerous small boats, in the vicinity of Bosnik, as well as the enemy positions on 

the Owi islands.41

That same day, JICPOA analysts commented that there had been considerable activity in connection 

with the New Guinea Reinforcement Force. The transportation force—the cruisers Aoba and Kinu and two 

destroyers—had sortied late on 2 June. This group was accompanied by the Covering Force, consisting of 

Fusō, the heavy cruisers Haguro and Myōkō, six destroyers, the 1st Supply Force (Nichiei Maru, Kokyo Maru,

and one other tanker), and two destroyers. The Japanese intent was believed to be to land troops on Biak 

probably on the night of 4 June. However, Japanese radio intelligence warned of a powerful enemy striking force near New Guinea. This was followed by a report of sighting an enemy force including carriers. 

Hence, the transportation force ran into Kabui Bay, Waigeo Island (off the northwest coast of New Guinea). 

The Covering Force sailed northward and arrived on 5 June at Davao, where it was refueled from the 1st 

Supply Force. However, the Japanese eventually discovered that the reports of enemy carriers were false. 

JICPOA believed that the KON operation had been either delayed or canceled (as in fact it had been, late 

on the 3rd) but that reinforcement forces would make a run to Biak at an early date.42

On 5 June, Nimitz informed task force commanders, on the basis of radio intercepts, that CruDiv 16 had 

arrived at Warparim Bay on Waigeo Island at 1055 on 5 June. His intelligence analysts believed that DesDiv 

19 (two destroyers) would sail with CruDiv 16. Four enemy destroyers had left Sorong at 0600 on the 5th 

for an unknown anchorage in that area for refueling. CruDiv 16 would try to disembark troops on Biak but 

probably not before the night of 5–6 June. CruDiv 5, plus possibly Fusō, had returned to Davao early on the 

5th, for reasons that were unclear but probably involved either fear of attack by the U.S. force believed to 

be north of New Guinea or the completion of troop transport to the Halmahera area.43

On 6 June, Nimitz’s headquarters informed commanders that the 1st Supply Force of the First Mobile 

Force had completed fueling CruDiv 5 and Fusō at Davao around noon the day before. CruDiv 16 was at 

Kabui Bay the morning of 5 June. DesDiv 19 (part of CruDiv 16), plus DesDiv 27, had arrived at Ambon (on 

the Banda Sea) about 0400 on the 6th. It was estimated that CruDiv 16 would land troops at Biak, but not 

before 7 June.44

On 7 June, COMINCH analysts learned that a newly formed KON force, based on CruDiv 16 units, was 

scheduled to take part in landings at Korim Bay on an unknown date. The analysts estimated this force 

at one heavy and one light cruiser, six to seven destroyers, and several smaller ships. The landing at Biak 

would start on 8 or 9 June. The 18th Guard Division at Manokwari, they reported, had informed Commander, CruDiv 16 at 1820 on 6 June that it would not be able to assist in the supply of Biak, as practically all its boats had been put out of commission by bombing and strafing.45 Combined Fleet had added 

CruDiv 5 and destroyers to the KON force. The army wanted troops to be transported by cruisers as far 

as Manokwari and from here shuttled to Biak by destroyers; however, Manokwari and Babo were being 

frequently raided and their small installations and craft were greatly damaged. Korim, a landing site on the 

north coast of Biak, was also under enemy monitoring, so a counterlanding would not be an easy task.46

JICPOA and COMINCH correctly deduced that Toyoda was now planning a second attempt to reinforce 

Biak. He had directed three DDs to embark six hundred troops at Sorong. They were escorted by another 

three DDs, each towing a large landing barge. The entire force was covered by CruDiv 5 heavy cruisers 

(Aoba and Kinu). Their aim was to land the troops on Biak during the night of 8–9 June. On the morning of 

the 7th, the parts of the force joined north of Missol Island, west of the Vogelkop Peninsula. The cruisers 

41 COMINCH Summaries of Radio Intelligence Japanese Naval Activities, 1 April 1944–30 June 1944, p. 1650.

42 JICPOA, “Estimate of Enemy Distribution and Intentions, April 1943–July 1944,” p. 292.

43 JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944, p. 1.

44 Ibid.

45 COMINCH Summaries of Radio Intelligence Japanese Naval Activities, 1 April 1944–30 June 1944, p. 1656.

46 Ugaki, Fading Victory, pp. 388–89.
J()

proceeded to Ambon and Salawati Island to replenish and then stand by. Sakonju’s force then steamed to 

Sorong to embark troops and at midnight departed for Biak. Daylight fighter cover was provided by the 

23rd Air Flotilla.47

Despite many setbacks, the Japanese had some successes. They carried out an air raid on the Allied 

airfield at Wakde on 8 June, inflicting significant damage on the runways and ground installations. Only a 

few Allied search aircraft were in the air at the time of the attack.48

At about 1230 on 8 June, ten SWPA B-25s escorted by seven P-38 fighters from Lake Sentani (near Hollandia) attacked Sakonju’s force of six destroyers about thirty miles northwest of Manokwari. One enemy 

DD (Harusame) was sunk, and three others (Shiratsuyu, Shikinami, and Samidare) were slightly damaged.49

The surviving destroyers continued toward Biak. At about 1900 Sakonju received a report from a Japanese 

bomber of an enemy force (Crutchley’s TF 74/75) some 120 miles east of Korim Bay. Crutchley’s force had 

no fighter cover, because of the shortage of the planes at Wakde. At 2340, one of Sakonju’s destroyers 

obtained contact with Crutchley’s force. Sakonju decided to withdraw, but that proved more complicated 

than he thought it would be.50

Shortly before, just after 2200, one PB4Y Privateer patrol bomber sighted an enemy force of five ships 

about sixty miles northwest by west of Crutchley and steaming at twelve knots in his direction. Crutchley 

issued a warning order for battle and set a course for intercept. His force detected the enemy at 2320—just 

before, as noted above, the enemy detected him and retired. During the two-hour stern chase that ensued, about 1,300 rounds were exchanged. Two enemy destroyers were hit, and one was slightly damaged 

by near misses; Crutchley’s force suffered no losses and prevented Sakonju from reinforcing Biak, except 

for a few troops landed from barges. Admiral Itō still had about 150 planes in the 23rd Air Flotilla, but these 

planes were recalled to help the First Mobile Force. Two of Sakonju’s destroyers (Shiratsuyu and Samidare)

went to Batjan, where they joined two heavy cruisers, Myōkō and Haguro. The remaining three destroyers 

(Shikinami, Uranami, and Shigure) proceeded to Sorong and disembarked their troops, after which they 

joined two Aoba and Kinu and proceeded to Batjan, where they arrived on 10 June.

Notwithstanding the failure of this second attempt to reinforce Biak, Ozawa was now even more determined to hold the island. On 9 June, he radioed Toyoda that Japan could not afford to lose Biak and its 

airfield. He argued that reinforcements might draw the American fleet into the anticipated zone of decisive battle and thereby enable the A-Go operation.Toyoda agreed and on the 10th, concluding that there 

were no enemy carriers in the area, decided to detach BatDiv 1 from the First Mobile Force and attach it to 

KON. BatDiv 1, under Admiral Ugaki, departed Tawi-Tawi at 1600 that day and arrived at Batjan the next. 

Two more destroyers were added to Ugaki’s force. The new attack force was now composed of BatDiv 1, 

with the two superdreadnoughts, Yamato and Musashi; two heavy cruisers, Myōkō and Haguro; one light 

cruiser (Noshiro); three destroyers; Sakonju’s Transport Force 1, with CruDiv 16 (Aoba and Kinu, plus four 

destroyers); and Transport Unit 2, with two minelayers, one transport, several submarine chasers, and a 

number of freighters.

Toyoda’s Operation Order No. 127 of 10 June stated that the KON force’s missions were (in order of priority) to destroy the enemy task force and reinforcements in the Biak area; bombard enemy landing forces 

on Biak and Owi; and transport the 2nd Sea Mobile Brigade to Biak at an opportune moment. Ugaki was 

directed if he received the order “Stand by for Operation A,” he was to continue KON but act so as to lure 

the enemy task force to the hoped-for decisive battle.51 Accordingly, Ugaki selected the Bafgan anchorage 

on Halmahera as his assembly point, effective at 1600 on 10 June.52

On 11 June, Nimitz’s headquarters told major subordinate commanders that BatDiv 1 had become 

associated in radio traffic with western New Guinea on the 10th, suggesting that its imminent departure 

for that area was possible. At about 1900, a U.S. submarine observed three battleships, four cruisers, and 

47 Morison, New Guinea and the Marianas, p. 125.

48 Ibid., p. 126.

49 Morison, New Guinea and the Marianas, p. 126; Cressman, Official Chronology of the U.S. Navy in World War II, p. 494; 

Ugaki, Fading Victory, p. 389; JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944, p. 1.

50 Morison, New Guinea and the Marianas, p. 126. The following, until the next citation, is drawn from this source, pp. 127, 

130–31, 220.

51 Ugaki, Fading Victory, p. 392; A-Go Operation, p. 24.

52 A-Go Operation, p. 25.
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readiness to cooperate with Ozawa. Other aircraft, including the Hachiman Group 

of forty-eight Mitsubishi G4M Type 1 (Betty) land-attack aircraft and forty-eight 

Jacks at Yokosuka, were in readiness to fly south if needed. These aircraft would 

attack TF 58 and TF 51.74

In mid-June 1944, about 880 U.S. Marine, Navy, and Army aircraft were based 

in the Marshalls and Gilberts. This number included about 330 fighters (including 

forty-four night fighters), 132 heavy and 112 medium bombers, seventy-two divebombers, forty-eight torpedo bombers, seventy-two patrol aircraft, and 128 miscellaneous aircraft (photographic, observation, transports).75 However, the Marianas, 

some 1,500 miles away, were far beyond the effective range of those fighters, divebombers, and torpedo bombers. Heavy bombers had sufficient range but could not 

be effectively used against carriers or other surface combatants.

TF 58 also had more battleships (seven versus five), light cruisers (thirteen versus two), and destroyers (fifty-six versus twenty-eight) than the First Mobile Force. 

The Japanese had a larger number only of heavy cruisers (eleven to eight).76 The 

First Mobile Force included two 71,700-ton (full load) superdreadnoughts (Yamato 

and Musashi), but most of its other battleships were obsolete. The oldest battleship, Kongō, had been built in 1913; only three battleships or cruisers had been 

commissioned after 1941.77 The number of destroyers was grossly inadequate. The 

Japanese had lost seven during the recent training and alert period.78 Finally, the 

U.S. carriers and large surface combatants possessed powerful antiair defenses, 

in the form of a large number of five-inch/38-caliber dual-purpose guns and 40 

mm and 20 mm guns. For example, an Essex-class carrier carried some eighty AA 

guns.79

The Japanese used twenty submarines in the A-Go operation, mainly in the 

vicinity of the Marianas. However, they did not have direct influence on the course 

destroyers en route southward from the Sibutu Passage and Tawi-Tawi. Commander in Chief, Pacific Fleet (CINCPac) 

assessed that it was probably BatDiv 1 (Musashi, Nagato, and Yamato), accompanied by either CruDiv 4 or seven 

other units.53 Radio traffic on the 10th associated CruDiv 16 and CruDiv 5 with the Biak-Manokwari area (a message 

had been routed to Biak for CruDiv 5). A Japanese message of 1717 on 10 June indicated that three destroyers of 

DesDiv 27 were still afloat and had not been sunk by B-24s on the 8th, as previously reported. Japanese messages 

sent at about 2000 and 2300 indicated that Menado was probably the immediate destination of BatDiv 1.54

By the evening of 11 June, the KON force was assembled at Batjan. Ugaki intended to land troops at all costs, 

at the same time bombarding enemy positions on Biak and Owi. However, by that time Toyoda was much more 

concerned about the Marianas. Allied planes attacked Guam and Saipan on 11 June and again the next day. Hence, 

at 1830 on 12 June, Toyoda issued orders to execute the A-Go operation and to suspend KON temporarily. Ugaki 

reversed course, headed north, and joined Ozawa’s force. At the same time, Toyoda ordered the 23rd Air Flotilla to 

move all aircraft then in New Guinea to Palau.55

53 JICPOA-CINCPAC Intelligence Bulletins, 10 May–30 June 1944, pp. 1–2.

54 COMINCH Summaries of Radio Intelligence Japanese Naval Activities, 1 April 1944–30 June 1944, pp. 1663–64.

55 Morison, New Guinea and the Marianas, pp. 131–32.
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and outcome of the operation.80 In contrast, the American TF 17 deployed four 

boats in the Bonins area, three boats southeast and eastward of Formosa, five boats 

east and southeast of the Marianas, five in the Ulithi-Philippines area, and one off 

the Surigao Strait. The Seventh Fleet deployed three boats southeast of Mindanao, 

four off Tawi-Tawi, and two off Luzon.81

The U.S. Navy enjoyed one of its greatest advantages over the IJN in an excellent 

capability for refueling forces at sea. Service Squadron 10 of Service Force Pacific 

was directly responsible for refueling the fleet during FORAGER. Admiral Spruance 

emphasized the importance of adequate and timely replenishment, because the 

U.S. forces would be operating in enemy-controlled territory farther from American bases than ever before.82

Until 15 June, the United States routed commercial tankers to Majuro and then 

diverted them to final destinations. Afterward, tankers arriving at the Marshalls 

were routed to Eniwetok. Two Liberty-type tankers were available there, and three 

or more station tankers were to be there by 20 June. A fleet-oiler task unit, composed of oilers and escorts, and an aircraft-replacement task unit, composed of 

an escort carrier plus escorts, was organized as TG 50.17. Its commander was responsible for coordinating the employment of all fleet oilers in the combat area. He 

sent fleet oilers back to Eniwetok for reloading when their black cargo oil had been 

reduced to twenty thousand barrels. He was also responsible for sending escort carrier units to Eniwetok for replacement aircraft. Eight task units (TU 16.7.1 through 

TU 16.7.8) were established for refueling at sea, each composed of three oilers with 

at least two destroyer escorts. Sometimes, one destroyer and two destroyer escorts 

were assigned. There were eleven rectangular refueling areas, each seventy-five by 

twenty-five miles, in the vicinity of the Marianas.83

The IJN made great efforts prior to the A-Go operation to ensure that there 

would be sufficient fuel, lubricants, ammunition, and other supplies for the First 

Mobile Force, Base Air Force, and other IJN units in the southern Philippines and 

the Central Pacific. In the IJN, all logistical responsibilities were concentrated at the 

Navy Ministry and NGS. 

The main reason for selecting Tawi-Tawi as a major naval anchorage was its 

proximity to Tarakan, Borneo, some 180 miles away; naval vessels could use crude 

oil from the Tarakan fields without refining. However, that oil was heavy in sulfur 

that could damage boilers. It was also highly volatile and posed a serious risk for a 

ship damaged in combat. Yet there was severe shortage of refined oil.84 For the A-Go 

operation, the Combined Fleet assigned three supply forces composed of seven to 

ten tankers and escorted with a few destroyers (see Japanese order of battle, above). 

The Allied Preparations, 2–9 June

All the U.S. forces taking part in FORAGER sortied from Hawaii the last week of 

May 1944 and headed directly for the main assembly area in the Marshalls, in the 
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lagoons of Majuro, Kwajalein, and Eniwetok. Admiral Spruance left Pearl Harbor 

on 26 May on board the heavy cruiser Indianapolis for the Marshalls.85 On 2 June 

Spruance’s flagship anchored at Majuro; two days later it arrived at Kwajalein and 

on 5 June at Roi. Spruance inspected installations on Roi and Namur.86

TF 58 had then to transit some 1,580 nautical miles from Majuro to an area off 

Saipan. It sailed on 6 June and refueled in the afternoon on 8 June; it took almost 

ten hours to refuel the entire task force. TG 58.7, the Battle Line (Admiral Lee), 

was specially organized for surface action and operated separately, but on 8 June 

it was incorporated into TF 58’s task group structure.87 CTF 57 directed additional 

searches for 8–9 June between bearings of 317° and 342° and out to five hundred 

miles from Eniwetok to cover the fueling of TF 58.88

On 7 June, Spruance arrived at Eniwetok and conferred on the final plan with 

his principal commanders, Turner (CTF 51 and CTF 52, the Northern Attack 

Force), Gen. Holland M. Smith, USMC (Expeditionary Troops, CTF 56), Mitscher, 

Hoover (CTF 57), and Rear Adm. Richard L. Conolly (CTF 53, Southern Attack 

Force).89 He received the plans of his task force commanders.90 He also inspected 

base development ashore.91 Spruance left Eniwetok in Indianapolis on 9 June and 

the next day joined TF 58. 

Spruance and his task force commanders continued to receive information on the whereabouts of the Japanese commanders and their forces. On 5 

June JICPOA deduced that commanders of the First Mobile and Second Fleets 

were in the southern Philippines, while that of the Combined Fleet remained 

in home waters.92 It estimated that the Japanese had available for combat in the 

Philippines–NEI area six battleships, two large carriers, two auxiliary carriers, five 

light carriers, twelve heavy cruisers, three light carriers, and thirty destroyers.93

It had been learned a week earlier that CINC, Central Pacific Area Fleet was Vice 

Adm. Chūichi Nagumo.94 Japanese reinforcements continued to flow into the 

Central Pacific, largely to the Palau–New Guinea area. One fighter and one divebomber squadron had been redeployed from Truk to New Guinea. Convoys continued to move troops and material from the Marianas to Yap and Palau; Saipan 

was an important transshipment point for the Carolines. JICPOA assessed that 

Japanese supplies of aviation gasoline and oil in the Marianas were dwindling.95 It 

also reported that the Japanese radio intelligence believed that a U.S. striking force 

might have sortied from Majuro during the night of 4–5 June.96

On 7 June, Nimitz’s staff estimated that Commander, First Striking Fleet (First 

Mobile Force) was at Tawi-Tawi with the main body of his fleet. CINC, Combined 

Fleet, it believed, was considerably concerned about west New Guinea and the Biak 

troop transport. The battleship Fusō, CruDiv 5, and DesDiv 10 were probably still 

at Davao, engaged in towing and fueling-at-sea exercises. There was good evidence 

that the tankers Ashizuri and Takasaki, or one of them, had been torpedoed and 
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sunk in the Sulu Sea en route from Tarakan to Yap via the Surigao Strait on the 

morning of 5 June. The 1st Supply Force consisted of three tankers (Nichiei Maru, 

Kokuyo Maru, and Seiyo Maru), and the 2nd Supply Force of two tankers, Genyo 

Maru and Azusa Maru. A force of one light cruiser (Natori) and two DDs, probably 

accompanied by one tanker (Hayasu), had sailed from home waters for Davao on 

6 June. JICPOA learned that the tanker in that force was carrying eighty five-inch 

hoses, ten 40 mm cables, and ten 48 mm cables five hundred feet long (all likely 

intended for fueling-at-sea rigs) for the First Striking Fleet. This tanker would sail 

from Davao to Balikpapan for refueling and then join the First Striking Fleet. From 

this single piece of evidence, the analysts concluded that the First Striking Fleet 

would sortie prior to 15 June.97

On 8 June, JICPOA deduced from Japanese radio traffic that the First Mobile 

Fleet might soon sortie from Tawi-Tawi. The Japanese were conducting an intensive 

antisubmarine search between Davao and Kau (Halmahera, North Maluku, Moluccas).98 JICPOA learned about the general situation in the area of the Japanese Southern Army from a decrypted message of 2 June. Among other things, the Southern 

Army had concluded (correctly) that Saipan would be the enemy objective that 

summer. It also believed that the bases in New Guinea would be captured by the enemy as quickly as possible, giving the Japanese too little time to consolidate their line 

of defense. The enemy would make an all-out attempt to occupy the Philippines and 

exert pressure on Japanese positions there after June. In the Indian Ocean, the Japanese believed, for the time being the enemy would conduct only harassing actions 

but would carry out a large-scale offensive after the end of the monsoon season, coordinated with actions in the Pacific theater. The Americans, the Japanese analysts 

were reported to believe, would also carry out an air offensive against Japanese reinforcements from northern Burma and China. The American analysts commented 

that the Southern Army had control over all army operations in the southwestern 

Pacific and Southeast Asia. Its headquarters had recently moved from Singapore 

to Manila.99 On 10 June, JICPOA revealed the existence of the 3rd Supply Force of 

the First Striking Fleet, composed of two tankers, Kosen Maru and Sunosaki-Kosen 

Maru. They were scheduled to arrive at Balikpapan on 8 June for refueling.100

Japanese Preparations through 10 June

The entire plan for the A-Go operation was rehearsed in a series of tabletop maneuvers and war games. There were also a number of meetings between the planners 

of the NGS and Combined Fleet Headquarters. Vice Adm. Seichi Ito, deputy chief 

of the NGS, flew to Singapore to hold detailed discussions with the staffs of subordinate commanders. Ito helped the chief of the NGS, Adm. Shigetarō Shimada, 

incorporate the A-Go operation plan into an IGHQ directive.101 The First Mobile 

Force was directed to assemble eventually at Tawi-Tawi anchorage but for the time 

being its main elements were to remain at Singapore and the Lingayen anchorage.102
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On 27 April, tabletop maneuvers were conducted on board Ozawa’s flagship, 

the carrier Taihō. Vice Adm. Matome Ugaki, commander of BatDiv 1 (and former 

chief of the staff of the Combined Fleet), who attended the game, wondered why 

the Japanese side did not try to attack elements that could be easily destroyed instead of seeking a decisive battle.103 He believed that the players, focused solely on 

fighting a decisive battle, seldom thought about an easy way to destroy elements of 

the enemy.104 On 2 May, war games and staff studies were held by the NGS aboard 

the Combined Fleet’s flagship cruiser Ōyodo, on board the carrier Taihō, and on a 

smaller scale on flagships of smaller units. Emperor Hirohito attended a critique of 

the NGS game on 2 May in Tokyo—the first time the emperor had participated in 

a preparatory planning session for a major naval operation.105

Ozawa held another table maneuver on 6 May.106 Three days later, a table maneuver was conducted by the Second Fleet. Ugaki was uncertain whether a decisive 

battle could be fought at all. At the same time, he suspected that the enemy might 

not be as good as the Japanese believed: everything “may turn out all right if and 

when we fight with them.”107

At about 0300 on 11 May, the First Mobile Force left Lingga for Tawi-Tawi. 

However, CarDiv 1, BatDivs 1 and 3, CruDivs 4, 5, and 7, and DesRons 2 and 10 remained at Lingga.108 The next day, CarDiv 1 and two submarines left Lingga. On 14 

May, the 2nd Diversionary Attack Force arrived at Tawi-Tawi. The next day, CarDiv 

1 and the two submarines reached Tawi-Tawi, at 1100.109 On 16 May, the First Mobile Force moved to a point west of the Inland Sea, where it joined the Third Fleet 

and Second Fleet.110 CarDiv 3 and the battleship Musashi arrived at Tawi-Tawi at 

about 1915 on 16 May.111

By May 1944 the Japanese had five army divisions and six independent regiments, plus numerous smaller units, in the 31st Army area. The 29th Division was 

sent from Manchuria to Saipan in February 1944 and later to Guam. The 43rd Division was moved from Japan to Saipan in late May 1944.112 Out of some forty-five 

thousand troops in the Marianas, all but five thousand were on Saipan, Guam, and 

Tinian.113

The IJN strengthened its forces in the Marianas too. Shortly after the fall of the 

Marshalls, the 55th and the 65th Naval Guard Forces were sent to Saipan and Tinian, 

respectively. The Japanese also increased their air strength, concurrently with the 

construction of the new airfields.114 In March 1944, the Combined Fleet and the Central Pacific Area Fleet issued separate orders for accelerated construction of fourteen 

airfields and two seaplane bases in the Marianas–Truk and Palau–Yap areas. Specifically, Saipan would have three airfields and one seaplane base; Guam, four airfields and one seaplane base; Rota, one airfield; Pagan, two airfields; and Tinian, four 

airfields. Each airfield would accommodate forty-eight aircraft. The exception was 

the Marpi airfield on Saipan, which had only twenty-four. Charan-Kanoa on Saipan 
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would be used as an emergency strip. The network of bases would accommodate 

altogether some six hundred aircraft. Combined Fleet directed that these airfields be 

completed by April 1944; however, this proved overly optimistic. When U.S. forces 

invaded the Marianas in June 1944, most of these airfields were not ready: the Marpi 

field on Saipan was unfinished; Guam had only two operational airfields, with two 

under construction; Tinian had three usable airfields and one under construction; 

and Rota and Pagan each had one runway. Out of fourteen airfields planned, nine 

had been completed, capable of operating about four hundred planes.115 On 18 May, 

the Base Air Force was told that it would execute A-Go with the 1st Air Flotilla.116

Deployment of the First Air Fleet was to be complete by 26 May. 

The next day, the commander of the First Mobile Force ordered, “Disregard 

damage. Part of the unit will be sacrificed for the overall success.”117 At 0930, Ozawa 

gave a speech to all subordinate commanders: “We do not consider our losses. If 

and when necessary for the sake of the main cause, an element will be sacrificed. In 

case communications and liaison go wrong, a commander must act as he sees fit.”118

On 3 May, IGHQ issued Order No. 373, “The Immediate Operational Policy 

(A-Go Operation) to Be Adhered by the Combined Fleet.” The same day Admiral 

Shimada issued Order No. 209, “Operational Policies to Be Followed by the Combined Fleet.”119 Among other things, he directed Toyoda to conduct “surprise” operations until the enemy’s “spirit for attack” was broken.120 Shimada envisioned that 

preparations for decisive battle by the First Mobile Force and First Air Fleet would 

be completed in late May. The First Mobile Force would assemble in the southcentral part of the Philippines. He directed Toyoda that after the First Air Fleet 

was deployed in the Central Pacific area, the Philippines, and north of Australia, 

“you will be in a state of readiness and taking advantage of a good opportunity, will 

employ your entire strength, . . . to engage and annihilate the enemy.” The decisive 

battle would be fought as close as possible to where Japanese forces were deployed. 

Should the enemy attack prior to the completion of preparations by the Combined 

Fleet, Japanese forces would secure “strategic points.” In that case, unless a favorable situation developed, the Combined Fleet would avoid a decisive surface engagement with the enemy fleet. The enemy should be diverted and annihilated by 

the Base Air Force and local area-defense forces.121

In his Order No. 209, Shimada stated that preparations would encompass an 

area stretching from the Central Pacific to the Philippines and north of Australia. 

They should be sped up in the western Carolines, the south-central Philippines, the 

Halmahera area, and western New Guinea. Priority should be given to air operations. Maximum efforts should be made in the construction of bases, air bases in 

particular, and the securing of required quantities of fuel and ammunition.122 In 

close cooperation with the Base Air Force, the First Mobile Force would engage 

the enemy forces and annihilate them in a “single blow.” All battle preparations at 
J

the anchorage in the southern Philippines would be completed by 20 May. A decoy 

force would advance to Ululsi or Palau and in cooperation with other Japanese 

forces induce the enemy to come out to where the decisive battle would be fought. 

The First Mobile Force would sortie and move east of the Philippines and at an opportune time absorb the decoy force.123 The Japanese forces should be also alert for 

an enemy attempt to attack from the flanks or to trap them.124

Also on 3 May, Admiral Toyoda issued his Order No. 76, on the operational 

policy to be followed by the Combined Fleet. The major part of the Base Air Force 

and the First Mobile Force would concentrate to lure the enemy fleet. The decisive 

battle would be fought with the entire strength of the First Mobile Force, upon a 

favorable opportunity, around Palau and the western Carolines. The majority of enemy carrier striking forces would be attacked and annihilated in daylight.125 Should 

the U.S. Pacific Fleet appear off the Marianas, it would be attacked by land-based 

aircraft only and lured southward toward Woleai–Yap–Palau where a decisive battle would be fought during daylight. The Japanese were confident of winning such 

a battle. The enemy would be pursued and subjected to continuous air, surface, 

and submarine attacks, including by aircraft based south and west of the Woleai–

Yap–Palau line.126 If the enemy attacked the Marianas or both the Marianas and the 

western Carolines simultaneously, counterattacks would be conducted by the Base 

Air Force.127

After the U.S. carriers attacked Marcus Island, the Japanese concluded that an 

assault on the Marianas was imminent. At midnight on 20 May, orders were issued 

to activate the A-Go operation.128 The First Mobile Force completed mobilization at 

Tawi-Tawi. The Base Air Force would start its deployment on 23 May and complete 

it three days later. By the end of May, the Japanese planned to move about 280 additional aircraft to the Central Pacific.129

During their preparations for the A-Go operation in late May and until 13 June 

1944, the Japanese had rudimentary knowledge of the strength and composition 

of the enemy forces in the Central Pacific. Most of their information was obtained 

by land-based naval search planes. For example, on 27 May, Japanese intelligence 

estimated that as of 2 June enemy strength in the Central Pacific and Inner South 

Seas would consist of five “regular” (fleet) aircraft carriers and five “converted” 

(escort) carriers, three battleships, three cruisers, twenty-one destroyers, twentynine transports, and nine small craft. In the Solomons, the enemy was believed 

to have one carrier, two converted carriers, two battleships, three cruisers, three 

destroyers, twenty-nine transports, and eighty small craft. In western New Guinea 

were one regular carrier, four battleships, seven cruisers, nineteen destroyers, sixty 

transports, and 120 small craft. The enemy’s total strength consisted of six regular 

carriers, seven converted carriers, eight battleships, twelve cruisers, forty-three destroyers, 116 transports, and 209 small craft.130
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On 30 May, the aircraft of the 22nd Air Flotilla at Truk reconnoitered Majuro 

Island and Finschafen Bay (fifty miles east of Lae, on the Huon Peninsula of New 

Guinea). They observed five aircraft carriers—two of the Essex class, one of the Enterprise class, and two of the Casablanca class—as well as one Iowa-class battleship. 

They also sighted three battleships, three cruisers, ten destroyers, two transports, and 

six tankers, or a total of twenty-nine ships at Majuro Atoll (two carriers, three battle 

cruisers, and eight destroyers were anchored outside the harbor).131 In Finschafen, 

the Japanese aircraft sighted nineteen ships (five large and six medium transports, 

five small transports, and three destroyers). At Kwajalein were observed eight destroyers, nine small ships, one tender, eighteen transports, one tanker, and twenty 

other ships, plus several aircraft. In the Admiralties were sighted one Saratogaclass aircraft carrier, one battleship, one cruiser, forty small ships, and one transport at anchor; 150 large and small aircraft were on the airfield.132

On 31 May, Japanese reconnaissance aircraft observed at Kwajalein eight destroyers, nine small ships, one small tender, eighteen transports, and a tanker, plus twenty 

other ships.133 On 2 June, aircraft based on Truk reported two cruisers, one destroyer, seventeen transports, one collier, twenty small aircraft, ten medium aircraft, and 

thirty large aircraft around Eniwetok, plus three large transports, ten small aircraft, 

and ten medium aircraft near Engebi (Enjebi today).134 On 4 June, Japanese reconnaissance aircraft detected eight converted carriers, six battleships, eight cruisers, 

sixteen-plus destroyers, and ten oilers.135 The next day, the Japanese reconnoitered 

Majuro and sighted five regular carriers, either Essex or Enterprise class, eight converted carriers (two of the Independence class), six battleships, eight cruisers, sixteen 

destroyers, and many others. In the Admiralties they observed one aircraft carrier, 

two battleships or battle cruisers, and five destroyers in Adora Harbor.136

At 0930 on 9 June, Japanese aircraft overflying Majuro reported that the enemy 

ships had departed; only ten transports and two destroyers remained.137 The same 

day, Japanese aircraft observed in the Admiralties the presence of one battleship, 

three cruisers, twenty transports, and about twenty destroyers, as well as 135 aircraft. The Combined Fleet ordered reconnaissance of Brown Island (west of Kwajalein) and of Kwajalein and strengthened patrols in the area.138 Reconnaissance of 

Majuro from Nauru on 9 June noted that the enemy had left for an unknown destination. One transport, two destroyers, and from ten to twenty large landing barges 

were sighted near the harbor entrance. Japanese submarines were also involved in 

the reconnaissance of Majuro Atoll.139
J

1 Commander in Chief Pacific Fleet [CINCPAC] Operation Plan 3-44, 1923 April 1944, p. 2, CINCPAC 

February 1944 to April 1944, box 26, Record Group 

[RG] 38, Records of the Office of the Chief of Naval 

Operations, Records Relating to Naval Activities 

during World War II: Plans, Orders and Related 

Documents, National Archives and Records Administration, Washington, D.C. [hereafter NARA].

2 Commander Fifth Fleet April 1944 to April 1945, p. 

21, folder April–May 1944, box 32, RG 38, Records 

of the Office of the Chief of Naval Operations, Records Relating to Naval Activity during World War II, 

World War II Diaries, NARA.

3 Ibid., p. 20.

4 Ibid., p. 21.

5 “General Plan for Employment of Fast Carrier Task 

Forces, Pacific (Task Force 58),” annex G, p. G-1, 

folder April–May 1944, box 32, Commander Fifth 

Fleet April 1944 to April 1945, RG 38, Records of 

the Office of the Chief of Naval Operations, Records 

Relating to Naval Activity during World War II, 

World War II Diaries, NARA [hereafter “General 

Plan for Employment of Fast Carrier Task Forces”].

6 Commander Fifth Fleet April 1944 to April 1945, 

p. 22.

7 “General Plan for Employment of Fast Carrier Task 

Forces,” pp. G-1–G-2.

8 Commander Fifth Fleet April 1944 to April 1945, 

p. 22.

9 Ibid., p. 19.

10 Ibid., p. 23.

11 “General Plan for Employment of Fast Carrier Task 

Forces,” p. G-1.

12 Ibid., p. G-2.

13 Ibid., p. G-3.

14 Ibid.

15 Ibid.

16 Ibid., p. G-4.

17 “Narrative Report: Operations of Task Force FiftyEight 11 June through 21 June 1944: Special Operations D Minus Four and D Minus Three Days,” p. 

2, folder Task Force 58, 11 September 1944, box 

215, TF 58 9-11-44 Vol. 1 to TF 58 9-11-44 Vol. 2, 

RG 38, Records of the Office of the Chief of Naval 

Operations, Records Relating to Naval Activity during World War II, WWII Action and Operational 

Reports, NARA.

18 Ibid., p. 3.

19 Operation Plan 3-44 Forager, 26 April 1944, annex 

D, Air Support, 14 May 1944, enclosure A, Headquarters Expeditionary Troops Task Force 56, p. 1, 

Combined Arms Research Library, usacac.army.mil/.

20 Operation Plan 3-44 Forager, 26 April 1944, annex 

C, Naval Gunfire Support, enclosure A, Headquarters Expeditionary Troops Task Force 56, p. 2, 

Combined Arms Research Library, usacac.army.mil/.

21 Submarine, Pacific Oplan Material, Archives Copy, 

May 1944, p. 1., box 298, SUBPAC February 1944 to 

May 1944, RG 38, Records of the Office of Chief of 

Naval Operations, Records Relating to Naval Activity during World War II: Plans, Orders and Related 

Documents, NARA.

22 G. Hermon Gill, Australia in the War of 1939–1945,

series 2 (Navy), vol. 2, Royal Australian Navy, 1942–

1945, 1st ed. (Canberra: Australian War Memorial, 

1968), p. 453.

23 Submarine, Pacific Oplan Material, p. 1.

24 Ibid., p. 2.

25 Commander Fifth Fleet April 1944 to April 1945, 

Aerological Plan, annex E, appendix I, p. E-I-2, 

folder April–May 1944, box 32, RG 38, Records of 

the Office of the Chief of Naval Operations, Records 

Relating to Naval Activity during World War II, 

World War II Diaries, NARA.

26 Ibid., p. E-I-6.

27 Ibid., p. E-I-5.

28 Ibid.

29 U.S. Strategic Bombing Survey (Pacific), Naval Analysis Division [hereafter USSBS], The Campaigns of 

the Pacific War (Washington, D.C.: U.S. Government 

Printing Office [hereafter GPO], 1946), p. 2.

30 Louis Morton, U.S. Army in World War II: The War 

in the Pacific—Strategy and Command: The First 

Two Years, CMH 5-1 (Washington, D.C.: U.S. Army 

Center of Military History, 1989) [hereafter Morton, 

Strategy and Command], p. 237; “Notes by Clarke 

Kawakami,” folder G-15, box 9, RG 23, Battle Evaluation Group, Naval Historical Collection, Naval War 

College, Newport, R.I. [hereafter NHC NWC].

NOTES
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31 Morton, Strategy and Command, p. 235; “Japanese 

War Planning,” interrogation of Admiral Mitsumasu 

Yonai, Interrogation NAV No. 76, 17 November 

1945, in USSBS Interrogations of Japanese Officials

(Washington, D.C.: GPO, 1946), vol. 2, pp. 328, 330.

32 USSBS, Campaigns of the Pacific War, p. 2.

33 Charles A. Willoughby et al., Reports of General 

MacArthur, vol. 2, part 1, Japanese Operations in the 

Southwest Pacific Area (Compiled from Japanese Demobilization Bureaux Records) (Washington, D.C.: 

GPO, January 1966, Facsimile Report, 1994), p. 319.

34 Outline of Third Phase Operations (February 1943 to 

August 1945), Japanese Monograph No. 117 (Tokyo: 

Foreign Histories Division, General Headquarters 

Far East Command, 1950), p. 5.

35 Samuel Eliot Morison, History of United States Naval 

Operations in World War II, vol. 13, New Guinea and 

the Marianas, March 1944–August 1944 (Boston: 

Little, Brown, 1953), p. 213.

36 The A-Go Operation, May-June 1944, Japanese 

Monograph No. 90 (Tokyo: Foreign Histories Division, General Headquarters Far East Command, 

1950), p. 3.

37 Outline of Third Phase Operations (February 1943 

to August 1945), pp. 2–3. The following discussion 

(through the next citation) is based on this source, 

pp. 6–8, 12.

38 Japanese Plan Z, 28 May 44, p. 3, folder CINCPAC 

FW, box 29, CINCPAC 14 May 44 to CINCPAC 31 

May 44, RG 38, Records of the Office of the Chief of 

Naval Operations, Records Relating to Naval Activity during World War II: Plans, Orders and Related 

Documents, NARA. The following discussion (to 

the next citation) is based on this source, pp. 4–8, 

15–20.

39 Outline of Third Phase Operations (February 1943 to 

August 1945), pp. 15–16. 

40 The same code name was given to the successful 

Japanese invasions of the first phase of the war in 

the Pacific; it was hoped the new A-Go operation 

would be equally successful. John Prados, Combined 

Fleet Decoded: The Secret History of American Intelligence and the Japanese Navy in World War II (New 

York: Random House, 1995), p. 555.

41 Bernard D. Cole, “Struggle for the Marianas,” Joint 

Force Quarterly (Spring 1995), p. 90.

42 Outline of Third Phase Operations (February 1943 to 

August 1945), p. 16.

43 Ibid., p. 17.

44 Ibid., p. 19.

45 Ibid., p. 17.

46 Ibid., p. 19.

47 A-Go Operation, p. 38.

48 Outline of Third Phase Operations (February 1943 to 

August 1945), p. 17. 

49 Night Operations Force Doctrine, 1 January 1944, p. 

1, Nachi Documents, Allied Translator and Interpretation Section, South West Pacific Area, No. 39 (Part 

II), 9 May 1945, G-55, RG 4, NHC NWC.

50 Ibid., pp. 2–3.

51 Ibid., p. 5.

52 Ibid., pp. 2–3.

53 Submarine Operations in the Third Phase Operations,

Japanese Monograph No. 184, parts 3, 4, and 5 (Tokyo: Foreign Histories Division, General Headquarters Far East Command, 1950), p. 31.

54 Ibid., pp. 37–39.

55 Morison, New Guinea and the Marianas, p. 233.

56 Barrett Tillman, Clash of the Carriers: The True 

Story of the Marianas Turkey Shoot of World War II 

(New York: New American Library, 2005), 

p. 124.

57 Ibid.

58 Morison, New Guinea and the Marianas, p. 233.

59 Thomas B. Buell, The Quiet Warrior: A Biography 

of Admiral Raymond A. Spruance (Annapolis, Md.: 

Naval Institute Press, 1987), p. 292.

60 Morison, New Guinea and the Marianas, p. 233.

61 E. B. Potter, Nimitz (Annapolis, Md.: Naval Institute 

Press, 1976, 1987), p. 299.

62 Tillman, Clash of the Carriers, p. 103.

63 COMINCH, Estimates of Japanese Air Strength 5 

January 1942–31 December 1945, p. 3, 011, entry A1 

9020, SRMN-045, container 15, SRMN 040 thru 047, 

RG 457, National Security Agency / Central Security 

Service, United States Navy Records, Relating to 

Cryptology, 1918–1950, NARA.

64 Ministry of Defence (Navy), War with Japan, vol. 4, 

The South-East Asia Operations and Central Pacific 

Advance (London: Her Majesty’s Stationery Office, 

1995), p. 131.

65 Morison, New Guinea and the Marianas, p. 235.

66 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, p. 131.

67 Ibid.

68 Morison, New Guinea and the Marianas, p. 235.

69 COMINCH, Estimates of Japanese Air Strength 5 

January 1942–31 December 1945, p. 5, 013.

70 Tillman, Clash of the Carriers, p. 102. 

71 Memorandum for Joint Intelligence Staff, “Appreciation Japanese Naval Air Force,” p. 1, Reference Joint 

Intelligence Staff Informal Memorandum 26 June 

1944, entry A1 9024, container 4, SRMD 12–16 

(Part III), RG 457, National Security Agency / 

Central Security Service, Intelligence Reports from 

U.S. Joint Services and Other Government Agencies, 

December 1941–October 1948, NARA. 

72 Ibid., p. 3.

73 A-Go Operation, p. 33.

74 Morison, New Guinea and the Marianas, p. 234.

75 USSBS, Campaigns of the Pacific War, p. 235.

76 Morison, New Guinea and the Marianas, p. 233.

77 Tillman, Clash of the Carriers, p. 102.

78 A-Go Operation, p. 34.

79 William T. Y’Blood, Red Sun Setting: The Battle of 

the Philippine Sea (Annapolis, Md.: Naval Institute 

Press, 1982), p. 33.
J

80 A-Go Operation, p. 63.

81 Morison, New Guinea and the Marianas, pp. 415–16.

82 Worrall Reed Carter, Beans, Bullets and Black Oil: 

The Story of Fleet Logistics Afloat in the Pacific during World War II (Washington, D.C.: GPO, 1953), 

p. 140.

83 Ibid., pp. 139–40.

84 Tillman, Clash of the Carriers, p. 39.

85 Buell, Quiet Warrior, p. 280.

86 ComFifthFleet War Diary for Month of June 1944, 

14 July 1944, p. 2, folder June–December 1944, 

box 32, Commander Fifth Fleet April 1944 to April 

1945, RG 38, Records of the Office of the Chief 

of Naval Operations, Records Relating to Naval 

Activity during World War II, World War II Diaries, 

NARA.

87 Y’Blood, Red Sun Setting, p. 34.

88 ComFifthFleet War Diary for Month of June 1944, 

p. 2.

89 Buell, Quiet Warrior, p. 281.

90 ComFifthFleet War Diary for Month of June 1944, 

p. 3.

91 Ibid., p. 2.

92 Joint Intelligence Center Pacific Ocean Area 

[JICPOA], “Estimate of Enemy Distribution and 

Intentions, April 1943–July 1944,” p. 289, entry A1 

9024, container 3, SRMD 8–11, RG 457, National 

Security Agency / Central Security Service, Intelligence Reports from U.S. Joint Services and Other 

Government Agencies, December 1941–October 

1948, NARA.

93 Ibid., p. 292.

94 Ibid., p. 289.

95 Ibid., p. 291.

96 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 2, folder 3222/23, box 108, 

JICPOA-CINCPOA Bulletins 1 December 1942–30 

June 1944, RG 38, Records of the Office of the Chief 

of Naval Operations, Records of Naval Security 

Group Central Depository Crane Indiana, Inactive 

Stations, NARA.

97 Ibid., p. 1.

98 COMINCH Summaries of Radio Intelligence Japanese Naval Activities (1 April 1944–30 June 1944), p. 

1658, SRNS 0719-SRNS 0809 (pp. 1487–1710), entry 

A1 9015, Summaries of Radio Intelligence Japanese 

Naval Attaché Messages (Japanese Naval Radio 

Intelligence Summaries, 1942–1946), container 3, 

SRNS 719–1083, RG 457, National Security Agency / 

Central Security Service, NARA [hereafter 

COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944].

99 Ibid., p. 1659.

100 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, pp. 1–2.

101 Prados, Combined Fleet Decoded, p. 567.

102 A-Go Operation, pp. 19–20.

103 Matome Ugaki, Fading Victory: The Diary of Matome Ugaki, trans. Masataka Chihaya, with Donald 

M. Goldstein and Katherine V. Dillon (Pittsburgh, 

Pa.: Univ. of Pittsburgh Press, 1991), p. 365; Prados, 

Combined Fleet Decoded, p. 555.

104 Ugaki, Fading Victory, p. 368. 

105 Prados, Combined Fleet Decoded, p. 567.

106 Ibid., p. 555.

107 Ugaki, Fading Victory, p. 368.

108 Ibid., p. 369.

109 The A-Go Operations Log: Supplement, May–June 

1944, Japanese Monograph No. 91 (Tokyo: Foreign 

Histories Division, General Headquarters Far East 

Command, 1950), p. 1.

110 A-Go Operation, p. 20.

111 A-Go Operations Log: Supplement, p. 2.

112 Cited in Philip A. Crowl, United States Army in 

World War II: The War in the Pacific—Campaign in 

the Marianas (Washington, D.C.: Office of the Chief 

of Military History, Department of the Army, 1960), 

pp. 57–58.

113 Ibid., p. 60.

114 Ibid., p. 58.

115 Cited in ibid., p. 61.

116 A-Go Operation, p. 20.

117 A-Go Operations Log: Supplement, p. 2.

118 Ugaki, Fading Victory, p. 373.

119 A-Go Operation, pp. 3–4. Shimada replaced Adm. 

Osami Nagano, who was dismissed by Prime Minister Hideki Tōjō in the aftermath of the Allied raid 

on Truk on 21 February. Shimada kept his post of 

navy minister.

120 Morison, New Guinea and the Marianas, p. 214.

121 A-Go Operation, p. 4.

122 Ibid., pp. 5–6.

123 Ibid., p. 27.

124 Ibid., p. 30.

125 Outline of Third Phase Operations (February 1943 to 

August 1945), pp. 16–17.

126 Morison, New Guinea and the Marianas, p. 215.

127 Outline of Third Phase Operations (February 1943 to 

August 1945), p. 17.

128 A-Go Operation, p. 20.

129 A-Go Operations Log: Supplement, p. 2.

130 Ugaki, Fading Victory, p. 384.

131 A-Go Operation, p. 21; A-Go Operations Log: Supplement, p. 5.

132 A-Go Operation, p. 22.

133 A-Go Operations Log: Supplement, pp. 6–7.

134 A-Go Operation, p. 22.

135 A-Go Operations Log: Supplement, p. 9.

136 A-Go Operation, pp. 22–23.

137 A-Go Operations Log: Supplement, p. 10.

138 Ibid., p. 11.

139 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1661.
V Japanese A-Go Operation (Battle of the 

Philippine Sea), 13–22 June 1944 

Execution

As envisaged in the basic plan, the Fifth Fleet launched a series of strikes 

against the Japanese positions in the Marianas between D–4 (11 June) 

and D-day (15 June). Spruance and his subordinate commanders received 

a steady stream of messages on enemy movements and intentions from the Joint 

Intelligence Center Pacific Ocean Areas (JICPOA) and U.S. submarines. Until Dday (15 June), the Fifth Fleet’s OPLAN 10-44 was executed as envisaged. The only 

exception was that on D–4 (11 June) the fast carrier task forces conducted a longrange fighter sweep of Guam, Rota, Tinian, and Saipan instead of delaying their 

initial attack until daylight on D–3 (12 June). This change in the plan was made 

because of the discovery of larger than estimated strength of enemy aircraft in the 

Marianas, an opportunity for surprise, and the desirability of altering the pattern of 

attacks in previous carrier attacks against targets ashore.1

Allied Pre-invasion Strikes, 11–15 June

On 11 June, TF 58 launched a fighter sweep of 225 aircraft against the southern 

Marianas from a position about two hundred miles from Guam and 225 miles from 

Saipan and Tinian. There was no indication that TF 58 had been detected, yet the 

Japanese offered considerable opposition in the air. Some 150 enemy aircraft were 

reported destroyed, including about eighty in the air. Reportedly, these strikes reduced Japanese air strength by about a third. TF 58 lost only eleven fighters; the pilots of five aircraft were rescued. Several Japanese vessels were destroyed at Saipan. 

The next day, TG 58.1 bombed Guam and Rota, while TG 58.4 struck targets on 

Saipan and Tinian. Mitscher steamed westward of the Marianas during the night.2

Aircraft of TG 58.4 attacked a Japanese convoy heading from Tanapag Harbor, on 

Saipan, to Japan.3

On 13 June, all four carrier groups of TF 58 conducted repeated air strikes 

against the Marianas. That night TG 58.2 and TG 58.3 retired northeast of Saipan. 

The next morning both groups returned to a position southwest of Tinian to strike 

Saipan, Guam, and Rota. TG 58.1 and TG 58.4 were en route to Iwo Jima. Battleships, cruisers, and destroyers of TF 51 bombarded Saipan. They encountered no 

air opposition and little antiaircraft fire.4

 The U.S. aircraft sank an already-damaged 
J

aircraft ferry and destroyed a convoy of five small cargo vessels. Battleships and 

destroyers of TG 58.7 conducted an almost-daylong bombardment of installations 

on Saipan and Tinian.5

On 14 June, TG 52.17 (Fire Support Group 1) and TG 52.18 (Fire Support 

Group 2) shelled Japanese installations on Saipan and Tinian. Japanese shore batteries damaged one old battleship, California, off Saipan and a destroyer off Tinian; 

one heavy cruiser (Indianapolis), one light cruiser (Birmingham), and a destroyer 

were damaged by near misses. Another battleship, Tennessee, was damaged by a 

shore battery northeast of Tinian.6

On 14 June, TG 58.1 and TG 58.4 refueled prior to planned strikes on Iwo Jima 

and Chichi Jima. Mitscher directed these two groups to limit their air strikes on 

Iwo Jima to 16 June only and to be ready the next day to engage the enemy fleet.7

During the night of the 14th, however, TG 58.1 and TG 58.4 were released to start 

their strikes the afternoon of the 15th to get in two days’ worth of attacks. The U.S. 

planes were intercepted over Iwo Jima. They shot down ten Zero fighters and destroyed seven other aircraft on the ground.8

 After TF 58’s U.S. carriers struck Iwo 

Jima the Japanese decided to stop their planned reconnaissance eastward of the 

Marianas. They tried to obtain information on enemy forces west of Palau through 

radio intercepts but were unsuccessful.9

In addition to TF 58’s and TF 51’s carrier strikes and bombardments, Allied 

long-range bombers based in the SWPA, SOPAC, and CENTPAC conducted, a 

week prior to the invasion of the Marianas, a series of intensive attacks against 

the Japanese strongholds in the Carolines. The aim was to isolate the Marianas 

from the rest of the Japanese-controlled positions in the Central Pacific. The heavy 

bombers of the Seventh and Fourteenth Air Forces struck Truk, Puluwat (Enderby), and Satawan Islands in the central Carolines.10 On 8 June, B-24 Liberators of 

the Seventh Air Force struck airfields on Truk.11 The next day the Thirteenth Air 

Force attacked airfields on Palau, Woleai, and Yap. B-24s from the Admiralty Islands bombed Truk and Satawan. On the night of 9–10 June Seventh Air Force 

Liberators bombed Truk.12 On 10–11 June SWPA Liberators attacked Palau, while 

the Seventh Air Force Liberators again bombed Truk.13

Long-range heavy bombers of the Thirteenth Air Force attacked Truk during the 

night of 11 June, while B-24s from SOPAC attacked Palau airfields.14 The next day 

Truk was bombed by the Army Air Forces Liberators before dawn, and by SWPA 

Liberators at midday. Liberators from Wakde and Manus attacked the Palaus before 

dawn.15 On 13 June, Seventh Air Force Liberators made a predawn strike on Truk 

and Thirteenth Air Force bombers struck during daylight. SOPAC B-24s made a 

night attack on Palau. On the same day, Seventh Air Force Liberators made a daylight attack on Truk, while B-24s from SWPA attacked Palau at night. On 14 June, 

SOPAC B-24s flew a night attack on the Yap airfields and a daylight attack on Truk.16
J()

Allied Information on the Enemy, 11–15 June

During the pre-invasion strikes on the Marianas, Admirals Spruance and Mitscher 

and other task force commanders were regularly kept informed by JICPOA on the 

locations, and in some cases the intentions, of enemy forces. On 12 June, JICPOA 

believed that the commander of the First Striking Fleet was still in the southern 

Philippines, probably at Tawi-Tawi, as was the commander of the Second Fleet. 

CINC, Combined Fleet was in Japan. Nimitz’s staff advised subordinate commanders that he believed it was too early to determine what course of action the First 

Striking Fleet would take in regard to the U.S. attack on the Marianas.17 Nimitz’s 

headquarters estimated that CruDiv 16 units had probably refueled from one tanker (Eiyo Maru) in the Sorong area on 11 or 12 June. CruDiv 5 was still associated 

with western New Guinea. In the morning on 11 June, an American submarine 

sighted a light cruiser (Natori), two destroyers, and an auxiliary carrier, with a 

deck load of aircraft, entering Davao Gulf; this group included one tanker, Hayasu,

probably carrying fueling gear for the First Striking Fleet. A U.S. submarine sighted 

two Fusō-class battleships and about six cruisers, plus several destroyers, anchored 

at Tawi-Tawi on 11 June. The continued presence of the battleships in the TawiTawi area had been confirmed by sightings of BatDiv 1 apparently proceeding to 

Menado.18

Nimitz’s assessment was that the connection of BatDiv 1 with Biak might mean 

that any fleet reaction to the Marianas operation had been postponed. No definitive commitment had been made for fleet employment in the New Guinea area, 

and an operation would require time for refueling and preparation. The Japanese 

plan called for fleet defense of the Marianas. However, it was believed that the Japanese would hesitate to risk their fleet without strong shore-based air support. By 

the time the fleet was ready, the possibility of shore-based air support might have 

disappeared. Nimitz’s intelligence staff saw no indication of a fleet movement into 

the Central Pacific. It estimated that the Japanese had available for combat in the 

Philippines–NEI area six battleships, two large carriers, two auxiliary carriers, five 

light carriers, twelve heavy cruisers, four light cruisers, and twenty-six destroyers. 

It also noted recent reports indicating that a comparatively heavy toll had been 

taken of Japanese destroyers. The unconfirmed estimates were that the IJN had lost 

by June 1944 about seventy destroyers, plus six destroyers probably sunk.19

Late during the night of 12 June, the U.S. submarine Bowfin reported an enemy force of four battleships, six cruisers, and destroyers entering the Sulu Sea 

near the northeastern tip of Borneo. However, Bowfin’s report was inconclusive. 

Hence, Spruance decided to proceed with the Saipan landings as scheduled and 

await further information about the enemy movements. He issued an alert to the 

Fifth Fleet and prepared contingency plans. There was a probability that the enemy 

might attack the Fifth Fleet on D+2 (17 June). However, an attack before that date 
J

was unlikely, because of the distances involved. Spruance had earlier scheduled an 

attack on Iwo Jima by carrier strike forces on 16–17 June.20

On 13 June, Spruance received his first information on the existence of Ozawa’s 

force from the submarine Redfin, which reported four battleships, six carriers, eight 

cruisers, and six destroyers heading north through the Sibutu Passage (an eighteenmile-wide channel between Borneo and the Sulu Archipelago).21 At the same time 

other information indicated a movement of enemy battleships from the Halmahera 

area into the waters east of the Philippines. Evaluating Redfin’s report, Spruance 

calculated that it would take the enemy force at least until 17 June to reach the 

Marianas; he also considered these reports still not definitive enough to cause any 

major change in the Fifth Fleet’s plans or dispositions.22 Hence, Spruance decided 

to continue scheduled operations for the next four days, including the landing on 

Saipan and the carrier strikes on Iwo Jima and Chichi Jima.23

Also on the 13th COMINCH analysts learned that at 2015 on 13 June a highpriority order originated by Combined Fleet (but transmitted from Tawi-Tawi) to 

First Striking Force and all major commanders indicated that a major fleet operation was under way. They estimated that the mission of the First Mobile Force was 

to attack U.S. forces in the Marianas. The enemy sighted by Redfin would apparently be joined by the forces that had sortied from the Batjan Islands (BatDiv 1). 

The First Striking Fleet would then be composed of six BBs, three carriers, two auxiliary carriers, four light carriers, eleven CAs, two light cruisers, and twenty-nine 

DDs. Another indication was a refueling for the First Striking Fleet arranged in a 

dispatch sent from Tawi-Tawi at 1614 on 13 June to the 1st and 2nd Supply Forces.24

JICPOA analysis in the afternoon and evening of 13 June of traffic between 

the Japanese naval high commands, plus messages sent by the commander of the 

First Striking Fleet to the 1st and 2nd Supply Forces, suggested that the enemy had 

reached a decision and that operation orders were being issued for surface action in 

the Marianas.25 JICPOA noted that sightings by submarines tended to confirm this 

conclusion. It further suggested that enemy forces would transit the Surigao Strait 

or the San Bernardino Strait. CarDiv 2 was in the Philippines area and would soon 

join the other carrier divisions. JICPOA also reported that BatDiv 1 and CruDiv 

5 (Haguro, Myoko), plus the light cruiser Noshiro and five DDs, had left the Batjan 

Islands at 2200 on 13 June, passed through position 01° 50ʹ north, 126° 50ʹ east at 

1400, and afterward proceeded to join the First Striking Fleet. Their rendezvous 

position was not known but was believed to be between Mindanao and the Marianas. JICPOA (correctly) assessed that the movement of BatDiv 1 northward would 

seriously hamper previous enemy plans for reinforcing Biak and other points in the 

western New Guinea area.26

On 13 June, COMINCH analysts assessed (erroneously, as it turned out) on the 

basis of radio intercepts that there was little evidence that the Japanese considered 
J()

the Marianas operation to involve anything other than carrier strikes. Their major reaction continued to be local. Also, there was no evidence of any concentration of surface forces for countermeasures, and little aircraft reinforcement to the 

Marianas had been noted.27 However, in what proved the first sign of the pending 

departure of major fleet units, CINC, Combined Fleet on 12 June ordered striking 

force units at Tawi-Tawi not to use radio except in an emergency. In the case of 

unavoidable necessity, messages should be carried by plane to Davao, Balikpapan, 

or elsewhere for transmission. There was, however, no evidence that CINC, First 

Mobile Fleet had departed Tawi-Tawi.28

The COMINCH daily summary of radio intercepts revealed that on the 13th 

Commander, Sixth Fleet had informed Toyoda that he had no submarines available for deployment eastward of Saipan. He had, however, directed two submarines to get under way for the area northeast of Truk, without having completed 

overhauls, at reduced speed. He had lost contact with five submarines assigned to 

patrol the “NA line” since their departure in mid-May. It was suggested by analysts 

that the two submarines mentioned had been damaged by antisubmarine measures by the escort carrier USS Hoggett Bay and its group. The other five submarines may have been sunk.29

On 13 June, Nimitz’s headquarters reported no indications of the locations of 

CarDivs 1, 2, and 3. They were estimated to be in the southern Philippines, however, with at least two divisions and Commander, First Striking Fleet probably 

at Tawi-Tawi. There was no satisfactory reason given for the previously reported 

movement of the 2nd Supply Force through the Surigao Strait on 6 June unless for 

fueling a task force of the First Striking Fleet. Recent sightings by U.S. submarines 

confirmed the general locations of all major units of the First Striking Fleet except 

CarDiv 1, which had been at Tawi-Tawi on 12 June. However, there was no evidence regarding the whereabouts of CarDiv 2 or 3; it was possible that they were 

at anchor in the Surigao Strait. The commander of the Second Fleet was unlocated 

on 12 June but was probably at Tawi-Tawi. As of the evening of 12 June, there 

were no indications of movement of any major Japanese unit toward the Marianas. 

By the evening of 12 June, the Japanese believed that U.S. surface vessels would 

possibly bombard important points in the Marianas starting early on 13 June and 

their ground forces were directed to prepare for a battle. Nimitz considered also—

erroneously—that the Japanese believed that the impending Allied actions against 

the Marianas would be another “hit and run attack.”30

TF 58’s estimate on the 13th of Japanese strength in the Halmaheras identified 

one division of new battleships and a division of cruisers, plus at least one squadron 

of destroyers. At Tawi-Tawi, it assessed, were three or four battleships; one division, 

possibly three divisions, of carriers; one division, possibly two divisions, of cruisers; and about twenty destroyers and some auxiliary vessels. Operating northwest 
J

of New Guinea against SWPA’s forces near Wewak were one or two divisions of 

cruisers, one battleship, and a destroyer. The Japanese had three replenishment 

groups, of which two were believed to be in the Philippines and one en route to the 

Philippines. One replenishment group operated in the Surigao area, awaiting rendezvous orders. In home waters and to the north were three battleships, approximately seven cruisers (heavy and light), two to three escort carriers, destroyers, and 

a considerable number of submarines. In the Marianas and western Carolines were 

deployed many Japanese submarines. Of the three carrier divisions operating in the 

Philippines, two were not definitely located.31

On or about 13 June, Mitscher and his staff estimated the enemy’s possible 

courses of action. This assessment was made on the assumption that the Japanese 

had fairly accurate information on the number of U.S. carriers involved, because 

of TF 58’s strikes on D–4 and D–3. The enemy also probably suspected that amphibious landings were about to start. The prevailing opinion in the Fifth Fleet was 

that the Japanese navy would not fight for the Marianas—notwithstanding, it was 

acknowledged, the statements of prisoners, captured documents, and the Japanese 

press, which (combined with the “peculiar” psychological attitude of the Japanese) 

all pointed to the possibility of a strong defense of the Marianas. At the same time 

there was a possibility that the IJN would participate in defending the Marianas 

provided that it had sufficient oil and tankers. Although many tankers had been 

sunk by U.S. submarines, some had reached ports in the NEI and were available. 

However, it was believed that only a few had sufficient speed to operate with the 

fleet at sea. Taking all this together, Mitscher and his staff cautioned that the Fifth 

Fleet must be prepared for “an aggressive hard hitting battle” if the Japanese did in 

the event venture to the eastward.32

Mitscher and his staff posited further that the attacks by TF 58 on Iwo Jima and 

Chichi Jima on D+1 and D+2 would probably destroy many planes on the ground, 

as well as air facilities. The Japanese would then require several days to ferry replacements to these airfields from the home islands. Further, strikes by General 

MacArthur’s B-24 Liberators against air bases on Palau and Yap would, even if not 

entirely successful, reduce the enemy’s air activity and prevent the enemy fleet from 

entering the area. Finally, enemy airpower in the Marianas had already been virtually destroyed by TF 58, but airfields remained operational, and the Japanese could 

bring more aircraft in.33

Mitscher, finally, assumed that the Japanese planes could operate as far as four 

hundred miles from land bases. The approaches to the Marianas could be searched 

with comparatively short hops from any of several bases. Guam and Rota were in 

effect additional “carriers”; they would allow Japanese aircraft to fly long-range attacks and then refuel. (The fact that Rota, a new field, was not used indicates a lack 

of fuel at that base.)34
J()

From all these considerations, Mitscher and his staff inferred three possible 

courses of action for the Japanese fleet: a southwesterly approach, from the general 

direction of Davao, under air cover from the Philippines, Palau, and Yap; a northwesterly approach, from the direction of northern Luzon; and a westerly approach 

from the central Philippines. The northwesterly approach was considered unlikely 

because of the longer transit time and higher fuel consumption it would require. 

An approach from the west was considered practicable. However, Mitscher and his 

staff (correctly) settled on the southwesterly approach as the most likely course of 

action for the Japanese fleet. It was shorter and thereby required less consumption 

of fuel. It was also favorable in that an equatorial weather front then moving eastward from the Philippines was heading in a northerly direction. Another advantage 

was that the enemy fleet approaching from the southwest would operate under 

cover of land-based aircraft during both its advance eastward and withdrawal. The 

greater number of enemy air bases in the southwest would also allow a more thorough search by fewer aircraft than if the Japanese fleet approached the Marianas 

from the west or northwest.35

As for whether the enemy could surprise and outflank U.S. forces, Mitscher and 

his staff thought it possible if the main enemy force steamed directly to the Marianas while a small, high-speed carrier unit ran close to Ulithi and attacked from 

the southern flank—or even from the rear, if the U.S. fleet went too far to the west. 

Allied land-based aircraft on Manus would search the southern area but could do 

so only during daylight hours. To ensure that U.S. forces would not be outflanked 

it would be necessary for the carriers themselves to conduct searches to their 

southwestward.36

In contrast to Spruance, Mitscher and his staff believed that even if part of the 

enemy fleet succeeded in approaching the landing area undetected, the threat 

would not be serious as long as the majority could be engaged west of the Marianas. In their view, the Fifth Fleet’s large force of old battleships, escort carriers, cruisers, and destroyers could cope with any part of the enemy fleet other than its new 

battleships in a surface action. In an air action, the Japanese would be able to inflict 

casualties, but the fighters carried by the escort carriers would make the attempt 

very expensive. Moreover, such a small diversionary force, after it carried out an 

attack, would be detected and destroyed by the forces defending amphibious shipping or the carrier groups. In Mitscher’s view, though there might be some losses 

on the American side to a diversionary Japanese carrier force, even if the Japanese 

chose to make such a suicidal attempt the Fifth Fleet could still attack the main enemy fleet approaching the Marianas from a westerly or southwesterly direction.37

Mitscher believed that Ozawa’s decision was in accordance with Toyoda’s desire 

to fight a decisive battle. In Mitscher’s view, there was nothing the Japanese could 

do with their fleet that could affect seriously the occupation of the Marianas, so 
J

long as the U.S. fast carrier task force could engage the major part of that fleet. 

Damage to the amphibious forces could be avoided if TF 58 did not move more 

than three hundred miles from the Marianas without definite indications of the 

location of the main Japanese force. Mitscher and his staff also believed that the 

Fifth Fleet could attack a diversionary force as easily from three hundred miles west 

(downwind) of the Marianas as it could from the vicinity of Saipan.38

On 14 June, JICPOA estimated that CINC, Combined Fleet had determined 

that present U.S. activities in the Marianas represented an invasion and not a diversionary strike. JICPOA believed that the Z operation order of 8 March was in 

general effect, with slight modifications. CINC, First Mobile Force, with his striking force from Tawi-Tawi, would refuel near the entrance to the Surigao Strait, to 

be joined there by CarDiv 2.39 JICPOA believed it possible that the First Striking 

Fleet would proceed to a point about 350 miles west or northwest of Saipan where 

it could take advantage of shore-based air searches and patrols based at Iwo Jima, 

Yap, Palau, Woleai, and Truk. It could also use floatplanes based at Ulithi and on 

board cruisers and battleships for antisubmarine patrols. A day surface engagement would probably require a decision by CINC, Combined Fleet, depending 

on the situation and effectiveness of the Japanese scouting and reconnaissance. 

JICPOA believed, however, that the First Mobile Force would have freedom to carry out night torpedo hit-and-run attacks. It warned that the enemy might carry out 

a surprise attack from the flanks. JICPOA concluded, finally, that the inclusion of 

CINC, Central Pacific Area Fleet as an addressee in two Combined Fleet messages 

suggested movement of the First Striking Fleet toward the Marianas.40

Also on the 14th JICPOA estimated that the enemy carrier force would have 

sortied from Tawi-Tawi at 1000 on 13 June and steamed at eighteen knots, to arrive 

at the Surigao Strait about 1300 the next day. Allowing six hours for refueling, the 

carrier force could sortie from the Surigao Strait at about 1900 on 14 June. (In fact, 

however, Ozawa’s main body sailed for Guimaras, between the islands of Panay and 

Negros.) BatDiv 1, at twenty knots, could arrive at Davao for refueling by 0200 on 

15 June. After six hours it could sortie and join the main body at a position that 

was unknown but was estimated to be 16° north, 140° east.41 At twenty knots it 

could reach that position by 0930 on 17 June. The enemy force, composed of six 

battleships and nine carriers, with accompanying cruisers and destroyers, could 

reach a position 16° north, 140° east by dawn on D+2 (17 June) at the earliest. The 

analysts pointed out that their deductions were based on the sightings by U.S. submarines and on traffic analysis, with only meager contributions by cryptanalysis. 

In estimating enemy capabilities, they cautioned, it would be well to consider the 

possibility that aircraft might be launched at extreme range, to land in the Marianas 

after attacking.42
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COMINCH analysts learned that at 0453 on 14 June the submarine Redfin had 

reported an enemy force of six carriers with planes on board, four battleships, eight 

cruisers, and about six destroyers in the northern Sibutu Passage at 1300 the day before on course 320°, speed eighteen knots. Nimitz estimated this force to comprise 

CarDivs 1 and 3; BatDiv 3 (Haruna, Kongō, Yamashiro, and Nagato); and CruDiv 7 

or 4, with Mogami and Yahagi, plus two other cruisers of either CruDiv 4 or CruDiv 

7. COMINCH analysts believed that CarDiv 2 was in the Zamboanga area. Redfin’s 

report of six carriers transiting the Sibutu Passage on 13 June pertained to CarDivs 

1 and 3; COMINCH suggested that CarDiv 2 might join them in the Sulu Sea.43

On 14 June, on the basis of Redfin’s report, Spruance advised all task forces of 

the Fifth Fleet that enemy forces might assemble and be within striking distance of 

the Marianas by 17 June. He directed TGs 58.1 and 58.4 to proceed to Iwo Jima and 

conduct planned air strikes. However, both carrier groups were advised that they 

might be recalled if the enemy fleet was approaching the Marianas.44 The refueling schedule was revised to allow the refueling of TGs 58.2 and 58.3 on 16 June.45

Spruance also directed Admiral Hoover (CTF 57) to send a patrol-plane tender 

to Saipan and be prepared to send a patrol-plane squadron there.46 Spruance also 

informed his subordinate commanders that Admiral Nimitz would direct Admiral 

Lockwood (CTF 17) to adjust submarine stations so to allow for reconnaissance 

and attack on the enemy fleet. Nimitz also requested General MacArthur to extend 

his long-range searches northwest of the Admiralty Islands to the maximum practicable distance (1,200 miles) on 15, 16, and 17 June, to cover possible routes of the 

enemy fleet toward the Marianas.47

On 14 June, Admiral Lockwood, as directed by Nimitz, adjusted the stations of 

submarine patrols.48 One day later he drew an imaginary sixty-mile square some 

five hundred miles west of Saipan and assigned four submarines (Albacore, Finback, 

Bang, and Stingray) to patrol thirty-mile radii around its corners.49 COMINCH 

analysts learned that radio intercepts on late 14 and early 15 June pertained to a 

rendezvous of tankers and escorts in the southern Philippine area. The addressees 

associated with the First Mobile Fleet included the 1st, 2nd, and 3rd Supply Forces 

(a total of ten tankers plus escorts). The analysts commented that several enemy 

tankers had passed through the Makassar Strait on 14 June and headed for the 

Davao area. A recent traffic association suggested that BatDiv 1 and accompanying 

vessels moving from Halmahera would refuel near Palau on 15 June. No information was available concerning refueling plans for other parts of the First Mobile 

Fleet.50

Also on 14 June, Nimitz’s fleet intelligence officer, Lt. Cdr. (later Rear Adm.) 

Edwin T. Layton, reported that Toyoda now considered the American activity in 

the Marianas an invasion, not another carrier raid. His bulletin explicitly referred 
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to the Z plan and predicted that a modified form of that plan would be carried 

out. Layton’s estimate of enemy strength (nine carriers plus six battleships) was accurate; he erred only in the date of the coming battle and the route Ozawa’s force 

would take. The intelligence forwarded to Spruance allowed him time to divert 

part of his force to bombard Iwo Jima. Daily radio intelligence summaries from 

COMINCH made it clear that the Japanese moves were neither unsuspected nor 

surprising in Washington, D.C. On 15 June, they noted that a Japanese plan to 

counter the invasion of the Marianas appeared to have been put into effect. Details 

of the enemy plan were not known, but the bulk of the Japanese fleet would be 

committed to the operation.51

Toyoda’s Orders, 11–13 June

After the U.S. carriers struck the Marianas on 10 June, Admiral Toyoda, in command 

of the Combined Fleet, had a clearer picture about his enemy’s intentions.52 On 12 

June, Japanese air reconnaissance obtained the first detailed information about the 

force approaching the Marianas. The Japanese search aircraft reported that it consisted of four groups: two “regular” carriers, one small carrier, and one battleship ninety 

nautical miles east of Saipan at 0550; two carriers ninety miles northeast of Saipan at 

0500; three carriers at unknown location at 0640; and two large carriers, two small 

carriers, and three battleships ninety miles southeast of Saipan at 1230.53

The First Air Fleet sent a summary of the enemy situation on 12 June. By collating 

reports of several reconnaissance aircraft from 11 June and observation by a Saipan 

reconnaissance aircraft, it estimated that the enemy force consisted of eleven aircraft 

carriers, of which three groups, with nine carriers between them, were close to the 

Marianas and a fourth group, with two carriers, was between 120 and two hundred 

miles east of the others.54 The next day Japanese reconnaissance of the Admiralties 

noted two cruisers and two destroyers leaving the harbor, four large and four medium carriers present, and ten battleships and eighty transports at anchor.55

On 13 June, Toyoda was informed that three battleships and fifteen destroyers 

were in the Saipan area; that two carriers, three battleships, and five destroyers were 

east of Tinian and two battleships and five destroyers to the west; and that eight or 

nine battleships, five or six cruisers, and a large number of destroyers were east, west, 

and south of Saipan.56 It was reported to Toyoda that between a hundred and two 

hundred aircraft had attacked Saipan, Tinian, and Guam in waves from 0430 to 0500, 

as well as strafing attacks throughout the day. Three enemy carriers had bombed Tinian and Guam.57 

At 1724 on 13 June, Toyoda issued an alert order (No. 146) for the A-Go operation. Another order (No. 147) temporarily suspended the Japanese effort to counter 

enemy landing on the island of Biak (KON operation) (for details of that operation 

see the sidebar “Allied Landing on Biak and Japanese Reaction, 27 May–11 June 

1944,” in chapter 4). BatDiv 1 (less Nagato), CruDiv 5, DesRon 2 (three destroyers), 
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and DesDiv 10 (two destroyers) were ordered back to their original formations.58 At 

the same time the 2nd and 3rd Attack Forces of the Base Air Force, then in the midst 

of reinforcing Halmahera, were directed west of the Carolines and to be ready for a 

decisive battle. The remainder of the 23rd Air Flotilla was to continue operations in 

western New Guinea.59 As of 13 June, Toyoda’s plan was that the First Mobile Force 

would attack the enemy regular carriers during the day, in cooperation with the Base 

Air Force; he tentatively set 19 June as the day to start. That date was uncertain because of a delay in the deployment of the Yawata Unit (part of the Yokosuka Air 

Group) to Iwo Jima.60 The Base Air Force would use airfields on Iwo Jima, Truk, 

Mereyon, Yap, and Palau. The Base Air Force would attack the enemy first and then 

await the arrival of the First Mobile Force. At the opportune time, the 7th Air Attack 

Force (less elements dispersed on Hokkaidō and in the Kuril Islands, and the Yokosuka Air Group) would employ its maximum strength in cooperation with the First 

Mobile Force and attack the invading enemy air force.61

First Mobile Force’s Initial Moves, 13–15 June

Ozawa’s First Mobile Force sortied from Tawi-Tawi at 1000 on 13 June. BatDiv 1, 

under Admiral Ugaki, departed the Batjan anchorage, Halmahera, that morning.62

At about 1615 Toyoda directed the 1st and 2nd Supply Forces to be alternately on 

thirty-minute alert. At 1704, the 2nd Supply Force was ordered to advance to a previously designated “Point A” and there to be on alert. At about 1745, the 3rd Supply 

Force was directed to reach Point J, there to stay on alert. Toyoda directed the First 

Mobile Force to sortie from Tawi-Tawi for Guimaras. The First Mobile Force sailed 

out at about 1800 on 14 June. The Japanese were aware that the enemy would learn 

about their movements; however, in their view, Guimaras was a better place to obtain 

supplies than Tawi-Tawi. From 1700 on 14 June to 0700 on the 15th the First Mobile 

Force took on board some 10,800 tons of supplies.63

At 1230 on 14 June, the First Air Fleet informed Ozawa of the presence of nine 

enemy battleships, five heavy cruisers, and more than thirty destroyers. This force, 

divided into four groups, bombarded Japanese positions ashore. At 1745 the Combined Fleet informed Ozawa that the force that had been raiding the Marianas since 

the 11th comprised almost the entire U.S. Navy’s strength in regular carriers. More 

than half had been involved in attacks on 11 and 12 June, and some had probably 

refueled in the rear on 13 and 14 June. The Japanese considered the invasion of the 

Marianas imminent.64

In the early morning of 15 June, Ozawa learned that some thirty enemy transports 

had appeared off the west coast of Saipan and started landing troops. A large enemy 

task force was attacking the Bonins and Iwo Jima.65 At 0717 on 15 June, Toyoda issued 

Order No. 154 for the execution of the A-Go operation: the “enemy commenced its 

landings in Saipan, Tinian areas with its powerful forces. The Combined Fleet will 

destroy the enemy task force which has come to the Marianas area, then annihilate 
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its invasion force in a decisive battle.”66 His message ended with a call for sacrifice: 

“The destiny of our Empire lies in the outcome of this battle. Each member will 

fight to the end.”67 At 0900 the main body of the First Mobile Force, less those ships 

involved in the KON operation (see the sidebar, chapter 4) sortied from Guimaras. 

At 1730 the same day, the First Mobile Fleet passed through the San Bernardino 

Strait and took an approximately easterly course toward the Marianas (see map 

13).68

On 15 June, Toyoda combined the 7th Base Air Force (centered on the 3rd Air 

Fleet) with the Yokosuka Air Group. He also directed the concentration of twenty 

submarines in the Marianas area.69 Because of the massive attacks by enemy fast 

carrier forces, the Base Air Forces had suffered such heavy losses that they were 

unable even to conduct reconnaissance in support of First Mobile Force. Hence, 

Ozawa had to rely on his own reconnaissance aircraft to detect the enemy fleet.70

The Approach Phase, 15–17 June

After exiting the San Bernardino Strait, Ozawa’s main body sailed on southeasterly 

until 1530 on 16 June. BatDiv 1—with CruDiv 5, DesDiv 2 (three DDs), DesDiv 

10, and DesDiv 4 (less one DD)—was joined by the 1st Supply Force at 1000 at 

11° north, 130° east. At about 1530, after being refueled, BatDiv 1 joined Ozawa’s 

force.71 All the ships of Ozawa’s main body and the destroyers of Force C started 

refueling on 16 June.72 The refueling was completed at 1000 on 17 June. The First 

Mobile Force was then at 12° 15ʹ north, 132° 45ʹ east. All six oilers then proceeded 

to 14° 40ʹ north, 134° 20ʹ east and stood by (see map 13).73

During the approach phase Ozawa was regularly informed by the Combined 

Fleet headquarters about the actions of enemy forces in the Marianas. For their 

part, Nimitz and his subordinate commanders received many reports based on intercepts of messages Toyoda sent to the First Mobile Force or Central Pacific Area 

Fleet. However, because of the radio silence observed by Ozawa’s force, JICPOA 

was unable to obtain information on its movement toward the Marianas. The most 

important and reliable sources of information on the movements of the First Mobile Fleet were reports by U.S. submarines.

On 15 June, Nimitz informed subordinates that Toyoda had transmitted several urgent messages in the morning on 15 June to Force A about the landings on 

Saipan. There was no definite information regarding Japanese plans. However, all 

indications pointed toward a movement to the east or northeast of Mindanao by 

the First Striking Force. That both the 1st and 2nd Supply Forces were associated 

in radio traffic with BatDiv 1 and the Davao–Palau area suggested that BatDiv 1 

would be refueled in that area. The commander of CruDiv 16 and Fusō was indicated as having been around Davao late on the 13th; this group was associated with 

the 1st Supply Force. A U.S. submarine found the Tawi-Tawi anchorage empty of 

enemy ships at 0700 on 14 June.74
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MINDORO

PAL WA

AN

Masbate

SAMAR

PANAY

NEGROS BOHOL

LEYTE

CEBU

0900

15

1300

14

MINDANAO

Davao

C E L E B E S S E A

Palmas

Basilan

Jolo

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S U L U S E A

Angaur

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T H E

P H I L I P P I N E

S E A

Mindoro Strait

LUZON

Main BodyBATDIV 1Supply ForcesU.S. 

Air Searches

Legend

San Bernardino

Strait

Surigao Strait

DINIGAT

0510

17

2115

17

CAVALLA

sighting

CAVALLA

sighting 2400

17

1000

17

refueling 16–17 June

1150 miles 1530 16

1300

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1945

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SEAHORSE

sighting

0345

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oiler stand-by area 14° 40’ N134° 20’ E

REDFIN sighting

1100

13

1835

F

15

LYING FISH

sighting

128° 130° E 132° 134° 126° 124° 122° 120°

14°12°10°8°6° N

120° 122° 124° 126° 128° 130° E 132° 134°

14°12°10°

8°

6° N

150 120 90 60 30 0

nautical miles

MAP 4: FIRST MOBILE FORCE: DEP

L

O

YMENT AND APPR

O

ACH PHAS

E, 13–17 JUNE 1944

Academics/jmo/2013/vego/BOPS

Map4

Map 13

First Mobile Force: Deployment and approach phase, 

13–17 June 1944
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Definitive information that the First Mobile Force had left the Philippine waters 

came at 1835 on 15 June, when the submarine Flying Fish reported that enemy 

battleships and at least three carriers had passed through the San Bernardino Strait 

at twenty knots on course 080°.

75At 2038 the Japanese learned by their own radio 

interceptions that an enemy submarine had discovered their position.76At 1945, the 

submarine Seahorse sighted an enemy force at 10° 11ʹ north, 129° 03ʹ east (about 

two hundred miles east-southeast of the Surigao Strait) on course 045°, speed 16.5 

knots. The composition of the enemy force was unclear, but on the basis of radar 

echoes it was thought likely to be BatDiv 1, on the way to join the force sighted by 

Flying Fish.

77 However, Seahorse was unable to transmit its sightings until 0400 on 

16 June.78

On 15 June, JICPOA learned from radio intercepts that all Japanese shipping 

west of the Marianas and south of 20° north had been directed to clear the area. The 

ships at Yap and Palau had been ordered to take refuge in the Philippines. Hence, it 

was estimated, the Seahorse sightings were possibly one of the three replenishment 

forces for the First Striking Force. Filipino coast watchers reported three carriers 

and seventeen warships at 11° 20ʹ north, 123° 23ʹ east at 1010 on 15 June, on a 

northerly course. Another coast watcher sighted nine carriers, three battleships, ten 

cruisers, and eleven destroyers at 1730 on 15 June at 12° 34ʹ north, 124° 09ʹ east, en 

route eastward. JICPOA estimated that the carriers belonged to CarDivs 1, 2, and 

3, the battleships to BatDiv 3 (plus Nagato), the cruisers to CruDiv 4 and CruDiv 7 

(plus Mogami and Yahagi), and the destroyers probably to DesRon 10.79

On 15 June, JICPOA reported that CINC, Combined Fleet had announced on 

14 June that a phase of the A-Go operation was in effect as of 1727 on the 13th and 

that the operation would be “decisive.” Nimitz believed that the pending Japanese 

operation would be similar to the Z operation.80 JICPOA also reported that the enemy search aircraft from Mindanao bases had been directed to fly antisubmarine 

patrols for the main body of the First Striking Fleet on 16 and possibly 17 June. 

Radio traffic analysis suggested that aircraft based on Yap and Palau were probably patrolling for the First Striking Fleet. CruDiv 16 was estimated to be in the 

Halmahera–Sorong area on 15 June.81

Ozawa received information that at 1215 on 15 June the enemy had appeared 

170 miles east of Guam and that at 1330 the same day it had started air attacks on 

Saipan, Tinian, Rota, and Guam. Air strikes had continued on the 16th. The Japanese estimated the enemy force as containing from ten to fifteen carriers.82

During the evening of 15 June, Ozawa and his staff issued an estimate of the situation. Ozawa believed that the enemy fleet was divided into five groups, containing 

altogether fifteen carriers, seven of the regular type and eight converted from cruisers. A group of supply ships, his estimate noted, was some four hundred nautical 

miles east of the Marianas. A group of tank landing ships had been observed in the 
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vicinity of the archipelago. The Japanese believed that the arrival of a large invasion 

fleet was imminent. Only a part of the enemy’s force of escort carriers had been 

detected, but it was believed that more would arrive in the vicinity of the Marianas. 

Japanese fighter aircraft had also reported (erroneously) the presence of eight carriers and other ships, including battleships and transports, in the Admiralties.

On 15 June, the Japanese high command and Combined Fleet agreed that the 

U.S. objectives were to invade and occupy “strategic” bases in the Marianas and 

invade “strategic” areas in the western Carolines and thereby draw out the First 

Mobile Force for a decisive battle. They believed that it was quite possible that the 

enemy had knowledge of the Japanese plans. Having intercepted radio messages 

from U.S. submarines, the Japanese assumed that the Americans knew about the 

sortie of the First Mobile Force from Tawi-Tawi on 13 June and its departure from 

Guimaras on 15 June. The Japanese also assumed that the enemy was aware of First 

Mobile Force’s plan to attack in the vicinity of the Marianas between 18 and 19 June.

On 15 June, Ozawa and his staff assumed that about two-thirds, or ten, of the 

enemy carriers would be deployed west of the Marianas and at a distance of not 

greater than three hundred nautical miles. The remaining carriers would support 

fighting ashore and act as a reserve. Ozawa thought that because of the combat 

situation ashore, there was very little possibility that all the enemy naval forces 

would leave the invasion zone and deploy temporarily east of the archipelago. Interestingly, Ozawa and his staff also considered it “very improbable” that the enemy 

would send part of his carrier force far to the west of the Marianas to carry out a 

flank attack against the First Mobile Force or to make a surprise attack, because it 

would then be operating in an area patrolled by Japanese land-based aircraft.

Ozawa correctly assumed that because the Japanese air bases were mostly in the 

southwestern Marianas, the Americans would probably attack the southern islands 

first and try to cut off air and other supply lines to the southwestern islands. At 

the same time the enemy would detach an element to attack in the north. Ozawa 

believed it very likely that the enemy would employ numerous escort carriers in 

the archipelago to reinforce the battle on land. For Ozawa, it was not possible to 

delay a decisive engagement beyond 19 June. He needed, he believed, to bring one 

about even sooner, and in fact Ozawa and his staff believed that, given the enemy’s 

deployments, the day of the decisive battle would be 18 June. 

Ozawa’s battle plan envisaged intensive scouting east of the enemy’s positions. 

He planned to arrive at a point some three hundred miles west of the Marianas so 

the First Mobile Force could attack enemy regular carriers to the east. He intended 

to use Battle Plan No. 1 (which envisaged a longitudinal array of forces) and Battle 

Plan No. 2 for daylight aerial battle. Ozawa planned to hold the 2nd Air Flotilla and 

reinforcements in reserve to guard against the surprise attack. At the same time, he 

intended to carry out “strict” (comprehensive) air patrols to the north. 
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Ozawa decided to intensify reconnaissance by adding land-based aircraft one 

day prior to and on the first day after the decisive battle. He stressed the need to 

differentiate between the regular and escort carriers. Ozawa laid down as the main 

tactical objective an attack on the enemy task force in the vicinity of the Marianas. 

Afterward, the objective would be to annihilate the enemy. In the south, scouting 

would be left to land-based aircraft. After success in the initial clash with the enemy, 

the entire force would pursue and annihilate the remainder. In case of lack of success, the First Mobile Force would retreat, reorganize, and then resume its attack. 

Ozawa also warned that the First Mobile Force should be on guard against attack 

after 16 June.

On 15 June, by a directive from IGHQ, the major part of the Yokosuka Air Group 

was placed under Toyoda. The Yawata unit was directed to proceed to Iwo Jima 

and report to the 5th Base Air Force. Prior to the decisive battle, about half the 5th 

Base Air Force was redeployed for the KON operation, greatly weakening its overall 

strength. Other problems were that many air bases were still under construction, 

personnel were unfamiliar with new aircraft, and the health of aircrews was poor. 

In the meantime, Spruance, on the night of 15 June, on the recommendation of 

Admiral Turner, designated 18 June as W-day (the initial landing on Guam), depending on the progress of fighting on Saipan.83 Nimitz designated the area westward of the existing “Class C submarine area” (reserved exclusively for operations of 

surface vessels and aircraft) bounded by longitude 134° east, between latitudes 10°

and 19° north, as a “Class D submarine area” (in which surface, air, and subsurface 

craft operate simultaneously), effective at 1200 (in the minus-ten time zone) on 16 

June.84

At 2253 on 15 June, Nimitz relayed his views, based on sightings and radio intercepts, that the enemy forces sighted by Flying Fish and Seahorse could, if they 

continued on their reported courses and speeds, effect a junction at approximately 

14° 50ʹ north, 134° 25ʹ east at about 2300 on 16 June. Steaming from the junction 

point at twenty knots they would reach the assumed position 16° north, 140° east 

at about 1430 on 17 June, from where they might be able to conduct carrier strikes 

against U.S. forces near Saipan. Most likely, however, the Japanese would be unable 

to initiate a surface attack on the night of 17 June.85

At 0354 on 16 June, Nimitz informed major subordinate commanders that 

Flying Fish had reported sighting a large task force at 1800 on the 15th. That force 

consisted of at least three battleships (one was Nagato), three carriers, several cruisers, and destroyers. It had exited the San Bernardino Strait on a course of 080° and 

at a speed of twenty knots. It was probably part of the First Striking Fleet, which had 

been sighted on the 13th transiting the Sibutu Passage.86 Flying Fish’s report lacked 

specific data on the number of carriers present, but it was believed that the force 

included all the carriers of CarDivs 1, 2, and 3, a total of nine.87
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Spruance was now certain that the Japanese were seeking battle and that they 

would risk everything in a determined attack. Hence, in his view, the landing on 

Guam was clearly not feasible.88 Hence, he canceled 18 June as W-day.89The Saipan 

invasion could not be canceled, because it had been under way for a day. Spruance 

boarded Admiral Turner’s flagship, USS Rocky Mount (AGC 3) to discuss with 

Turner and Gen. Holland Smith changes in the plan because of the probable fleet 

action.90 Also discussed were measures to be taken for the support of shore operations and the security of TF 51 in case the enemy tried to interfere with operations on Saipan.91 Spruance, much concerned about the safety of the transports, 

asked Turner whether they could be moved to a safer position to the east. Turner 

responded that battle ashore was going badly and that he was reluctant to move 

the transports; the troops ashore needed the food and ammunition still on board. 

Spruance told Turner to move everything he did not need eastward; TF 58 would 

try to keep the Japanese “off his neck.”92

Turner agreed to detach temporarily five heavy cruisers, three light cruisers, and 

twenty-one destroyers on 17 June to reinforce TF 58 for a surface action. The ships 

were sent west of Saipan as a blocking force.93 This left only seven battleships, three 

cruisers, and five destroyers for fire support ashore and local defense, and seven 

escort carriers for air support. The transports of the southern attack forces carrying Guam invasion troops were directed to remain at sea about two hundred miles 

east of the Marianas. All ships of the northern attack force not actually needed at 

Saipan would move eastward until called back. Holland Smith had already landed 

his Saipan reserve and enough supplies ashore to give the troops a reasonable expectation of being able to carry on until the immediate threat of the Japanese fleet 

could be taken care of. Six radar-equipped aircraft from Eniwetok were ordered to 

start night searches out to six hundred miles.94

Spruance ultimately made the decision to continue unloading at Saipan on 17 

June. As many transports as possible would be withdrawn at night, and only those 

urgently required would return on 18 June. The old battleships, the cruisers, and 

the destroyers of the bombardment group would cover Saipan from westward. At 

the same time, the southern attack force would be withdrawn eastward.95

On the morning of 16 June, Mitscher informed his task force commanders of 

his view that the Japanese would approach the Marianas from a southerly direction 

under shore-based air cover and close to Yap and Ulithi. They would attempt to operate in the vicinity of Guam. He also believed, however, that the enemy fleet might 

approach instead from the west—“Our searches must cover both possibilities.”96

In the afternoon on 16 June, TGs 58.1 and 58.4 conducted fighter sweeps over 

Chichi Jima and Haha Jima.97 As mentioned above, about ten Zeros were shot 

down, and seven enemy aircraft were destroyed on the ground. The U.S. side lost 

two planes over Iwo Jima and Chichi Jima. The U.S. aircraft set on fire three small 
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freighters and destroyed twenty-one seaplanes.98 Spruance ordered two carrier 

groups to make fighter sweeps over Iwo Jima and Chichi Jima on 16 June—a mistake, because that made them unavailable to conduct searches jointly with the other 

two carrier groups.

Spruance directed Mitscher to assemble his task groups so as to be ready to fight 

the next day (17 June). Mitscher would conduct minimum air operations on that 

day.99 TG 58.2 and TG 58.3, with reinforcing units of TF 51, would join at 1600 on 

17 June.100 TGs 58.1 and 58.4 would start searches north and west of the Marianas. 

The movements of a refueling group would be adjusted to allow early fueling of 

TGs 58.1 and 58.4. In addition to the planned searches, TG 58.1 would conduct 

strikes against targets on Guam and Rota, while TG 58.4 struck Pagan. However, air 

support for U.S. forces on Saipan would stop. At the same time, Spruance directed 

CTF 57 to send six patrol planes of Patrol Squadron 16 to Saipan on 17 June and 

prepare to make night radar searches out to six hundred miles west of Saipan.101

On the Japanese side, at 1850 on 16 June Admiral Kusaka, chief of staff of 

the Combined Fleet, informed Ozawa about the enemy activity in the Marianas. 

Ozawa now learned that the enemy had landed a large force on Saipan near Charanca at 1000 on 15 June and established a beachhead there. Because of a massive 

bombardment, the Japanese forces had been unable to repulse the landing. Kusaka 

also informed Ozawa that an enemy submarine near Mindanao had sent two urgent messages to the commander of the U.S. Pacific Fleet reporting the detection 

of his (Ozawa’s) force. Kusaka estimated (correctly) that the decisive battle would 

take place west of the Marianas on or about 19 June. The Base Air Force would intensify reconnaissance after 18 June. Japanese forces other than the Combined Fleet 

would conduct reconnaissance out to six hundred miles between bearings 90° and 

190° from Koroku, on Okinawa; out to seven hundred miles between bearings 90°

and 120° from Toko, on Formosa; and out to six hundred miles between bearings 

90° and 140° from Toizaki, on Kyūshū. Kusaka also pointed out the difficulty of 

distinguishing from the air between the enemy regular and converted (escort) carriers; however, he thought, those operating near the amphibious forces were most 

likely of the converted type. The best time to attack them would be while they were 

refueling. Most of the enemy battleships observed around Saipan and Tinian were 

of older types. Admiral Kusaka, finally, informed Ozawa that the enemy carriers had 

sustained considerable aircraft losses since 11 June but that they had replaced those 

losses from the escort carriers. (Kusaka had been misinformed by Admiral Kakuta, 

commander of the First Air Fleet, about the losses inflicted on the enemy carriers.)102

In Washington, COMINCH analysts observed that enemy radio traffic on 16 

June was almost entirely concerned with operational reports from the Marianas, 

with the Guam station apparently covering for Saipan. Almost all reports were 

being directed to “Force A” (Ozawa). The exchange of messages between high 
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commands practically stopped; none had been noted between Ozawa and Toyoda. 

Throughout the day, Toyoda was actively directing Central Pacific Area Fleet forces. 

He also ordered air searches from the bases on Palau and Truk.103

Nonetheless, on 16 June Ozawa received a message from the Central Pacific 

Area Fleet that east of the Marianas had been sighted nine enemy carriers (including two escort carriers), four battleships, fourteen cruisers, and about fifteen 

destroyers. The enemy force west of the Marianas consisted of three carriers, five 

battleships, twelve cruisers, thirty-eight destroyers, and eighty-seven transports. 

North of Truk were two enemy carriers, one battleship, three cruisers, and other 

ships, heading west. Some 350 miles south of Truk had been observed two enemy 

carriers and over a dozen other ships, steaming south. Within 150 miles southeast 

of Iwo Jima there were reported to be three enemy carriers. The Japanese estimated 

that the enemy forces consisted in all of seventeen carriers, eight battleships, more 

than thirty cruisers, over fifty-five destroyers, and eighty transports.104

At 2220 on 16 June, Kusaka transmitted an estimate of the situation in the Marianas. Among other things, he stated that the enemy invasion force consisted of a 

force centering on regular carriers; a supporting force of converted carriers, battleships, cruisers, and destroyers; and an invasion (landing) force. Most of the enemy’s 

regular carriers seemed to be involved in the operation. The force consisted of four 

carrier groups, each composed of two large carriers, three cruisers, and two battleships. Three carrier groups had taken part in the attacks on Saipan, Tinian, and 

Guam on 11, 12, and 13 June, while another group protected a landing force some 

two hundred miles east of Saipan and was refueled. After 14 June, only one carrier 

group had been left in the vicinity of Saipan and Guam. The air raids on Iwo Jima 

and Chichi Jima had been conducted by one or two groups on 15 and 16 June, while 

at least one other carrier group had probably refueled and prepared to engage the 

First Mobile Force. The enemy’s supporting force had appeared near Saipan on 14 

June and bombarded Saipan and Tinian every day, as well as Guam on 16 June. 

That force consisted of a number of converted carriers that seemed to have taken 

part in the amphibious landing. It was also probable that some of the battleships 

that had been with the task force until 12 June were part of the force. Kusaka estimated that a division of troops had landed on Saipan and that more seemed likely 

to follow from the Marshalls. It was unlikely that troops would come from the Admiralties. He estimated that the enemy would try to land on Guam about 17 June. 

In his view, there was a possibility that the enemy suspected the movement of the 

First Mobile Force and would be “massed” to meet it. The enemy might also try to 

neutralize Yap and Palau around 18 June.105

On 16 June, Toyoda replied to a message he had received from the emperor: 

“Your humble subject is filled with awe upon receiving word from Your Majesty 

through Your Majesty’s Chief of Staff. All members of the fleet and Army units 
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under my command, in obedience to Your Majesty’s Command, will fight and 

achieve victory by Grace of God. Our garrison in the Saipan area intends to annihilate the enemy, and the task forces intend to annihilate the enemy task forces at 

an opportune time when the enemy is occupied with the landings on Saipan. Thus, 

the wishes of Your Imperial Majesty shall be fulfilled.”106

That same day, COMINCH daily radio intercepts summaries showed continued and increasing association of CINC, First Mobile Fleet with the Marianas–

Bonins. The analysts concluded that the Striking Forces were “at present destined 

for action in the central Pacific.” CINC, Combined Fleet was embarked on the light 

cruiser Oyodo, believed to be in home waters. Radio traffic on 15 June concerning the 1st, 2nd, and 3rd Supply Forces suggested that final dispositions, escort, 

and composition of these forces were incomplete. All three were in vicinity of the 

southern Philippines but not necessarily joined.107

Shortly after midnight on 16–17 June, TGs 58.2 and 58.3 completed refueling 

off Saipan. In the process they had moved far to the east; Mitscher directed them to 

steam at twenty-three knots to join the other two carrier groups. Mitscher’s intent 

was to get as far westward as possible to close the distance to Ozawa’s force, because 

of the need to use easterly courses for launching and recovering aircraft.108 The two 

groups sent night searches out to 270–350 miles at about 0200. The planes returned 

about 0700; all their searches were negative.109

At about 0510 on 17 June, the submarine Cavalla, on the way to relieve Flying 

Fish off the San Bernardino Strait, reported a group of two large oilers and three 

destroyers at 13° 29ʹ north, 130° 45ʹ east on course 120° at 15 knots (see map 13). 

This was in fact the 2nd Supply Force, which had followed Ozawa’s force from Guimaras.110 Cavalla was directed by Admiral Lockwood to maintain contact but was 

unable to do so because of inadequate speed.111

Shortly after 0700, TGs 58.2 and 58.3 conducted 325-mile searches between 

bearings 215° and 285°. None of them detected the enemy force.112 TGs 58.1 and 

58.4 were directed to search between 215° and 285 out to 325 miles (between 15°

and 20° north). Both groups were later directed by Mitscher to keep under surveillance the area between 138° east and south of 20° north until they joined the rest 

of TF 58.113

At 0845 on 17 June, Rear Adm. Keizō Komura, chief of staff of the First Mobile 

Force, sent to the Combined Fleet, the 5th Base Air Force, and the Central Pacific 

Area Fleet a message informing them that the refueling had been completed and 

the entire force would advance to a general location west of Saipan via Point C (15°

0ʹ north, 136° 0ʹ east), arriving by dawn on 19 June. The intent was to guard against 

enemy movements to the west and from the north. The primary objective was to 

attack the enemy regular carriers and then, using all available strength, to destroy 
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remaining enemy forces and the invasion force. For security reasons, this message 

was initially sent by plane to Palau, where it was transmitted to the recipients.114

Also on 17 June Ozawa received information that around Saipan and Tinian the 

U.S. Navy had concentrated four or five converted carriers, four or five battleships, 

four to six cruisers, thirty destroyers, and sixty transports. North of Rota were six 

carriers, eight battleships, and eighteen cruisers and destroyers.115 Ozawa requested 

the Base Air Force to maintain continuous reconnaissance of the enemy regular 

carriers in the Marianas beginning on the evening of the day prior to a decisive 

battle. Ozawa also asked for intensified reconnaissance west of the Marianas by 

each air base on the day preceding the decisive battle. He stated that special importance should be attached to the southern and southwesterly sectors (between 160°

and 210°) from Iwo Jima. If the Yawata Air Unit had not deployed as planned, the 

decisive battle should be delayed by one day.116

During the afternoon of 17 June, Mitscher radioed to Spruance the disposition 

of his carrier groups and options for their employment once Ozawa’s force was detected.117 If the battle with the enemy fleet started before TGs 58.1 and 58.4 arrived, 

TG 58.2’s carriers would be designated as the “battle line.” If the battle were fought 

after TG 58.1 and TG 58.4 arrived, TG 58.4’s carriers would become the “battle 

line.” After the first air battles had been fought and TF 58 had obtained control 

of the air, CruDivs 10, 13, and 12 and DesDivs 11, 1, and 90 would be released to 

join TG 58.7. After the initial air battle—or before, if it became feasible—TG 58.1 

would take a station about fifty miles north-northwest of TG 58.3 to strike from the 

northern flank and cut off the enemy from escape to the north.118

At 1800 Mitscher recommended to Spruance that TF 58 change course to 310°

until reaching 16° north, then turn to 270° until after the daylight launch of search 

aircraft. He hoped that “this would allow us to flank the enemy, keep outside of 400 

miles range of the enemy fleet and far from the land-based aircraft based on Rota 

and Guam and still be in a position to hit the enemy carriers groups downwind 

from TF 58.”119 Mitscher’s intent was to move a good distance to the west during the 

night to be able to operate aircraft on an easterly heading the following day and to 

rendezvous with TGs 58.1 and 58.4 on the 18th. He explained that the same general 

plan would be followed on each successive day, so that if the winds were light and 

the launches long, TF 58 could still keep to the west and intercept an attack beyond 

the range at which the enemy could strike Saipan.120

Spruance initially approved Mitscher’s plan. Mitscher replied with a “proposed 

plan for strike on enemy surface force. Make deck load launch from CVs [fleet 

carriers] consisting of sixteen VF [fighters], twelve VB [dive-bombers], and nine 

VT [torpedo bombers]. Second deck load sixteen VF and available VN [training 

aircraft] and VT. Second deck loads prepared for launch as second wave unless 
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situation indicated delay advisable. Augment VT from light carriers as practical. 

Arming VT half torpedoes, VB half GP [general-purpose bombs], half SAP [semiarmor-piercing]. Later strikes include AP [armor-piercing] as targets indicate.”121

At 1415 on 17 June, Spruance issued his battle plan to CTF 58 and Commander, 

Task Group 58.7:

Our air will first knock out enemy carriers, then will attack enemy battleships and cruisers 

to slow or disable them. Battle Line will destroy enemy fleet either by fleet action if enemy 

elects to fight or by sinking slowed or crippled ships if enemy retreats. Action against the 

retreating enemy must be pushed vigorously by all hands to ensure complete destruction 

of his fleet. Destroyers running short of fuel may be returned to Saipan if necessary for 

refueling.122

For some reason, Spruance’s plan did not refer, directly or indirectly, to the possibility of an enemy “end run.”

That afternoon Nimitz sent Spruance a message: “On the eve of possible fleet 

action . . . you and the officers and men under your command have the confidence 

of the naval service and the country. We count on you to make the victory decisive.”123 Nimitz clearly expected a victory over the enemy fleet.

In the late afternoon, Mitscher requested permission from Spruance for significant changes in the composition of TF 58. He wanted to save time and avoid 

possible confusion in case of a sudden need to fight a surface engagement with 

Ozawa’s forces, by re-creating the battle line (TG 58.7) under Admiral Lee. At 

1730, Mitscher directed seven fast battleships (Washington, North Carolina, Iowa, 

New Jersey, South Dakota, Alabama, and Indiana), with two cruiser divisions (four 

CAs) and four destroyer squadrons (thirteen DDs), to leave their respective carrier groups and form TG 58.7.124 Afterward, Spruance approved the addition of 

CruDivs 6 and 12, DesRon 45, and DesDivs 1, 12, and 106 to that force.125 It was realized that this decision would reduce shipboard AA defenses of the carrier groups. 

However, it was believed that one cruiser division and destroyer division would be 

sufficient.126

Replying to a query from Mitscher on movements during the night, Spruance 

told Mitscher, with a copy to Lee, “Desire you proceed at your discretion selecting 

dispositions and movement’s best calculated to meet the enemy under most advantageous conditions. I shall issue general directive when necessary and leave details 

to you and Admiral Lee.”127

In the evening on 17 June, Spruance believed that the enemy fleet approaching 

the Marianas consisted probably of five battleships, nine carriers, eight heavy cruisers, and a number of destroyers. Spruance estimated that the enemy would probably conduct strikes by carrier-based aircraft, supported and followed by heavy 

fleet units.128 The enemy fleet might be divided in two parts, one of them, with 

carriers, coming around one of the American flanks. In Spruance’s view, if TF 58 

were moved too far from Saipan before the enemy’s location was definitely known, 
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such a flank attack might inflict heavy damage on the amphibious force there. The 

enemy flanking force would be able to escape to the northward or southward. The 

airfields on Guam and Rota would be available to the enemy unless U.S. carrierbased aircraft were able to keep them neutralized.129

Spruance and his chief of staff, Rear Adm. Charles J. “Carl” Moore, reevaluated the 

enemy movements and increased air activity. It seemed to them that the enemy knew 

the location of TF 58 and was shadowing it, deliberately staying beyond the range 

of U.S. search aircraft. It looked as if the Japanese intended to attack Turner’s forces 

while avoiding TF 58, perhaps by luring Spruance westward. Submarine reports indicated that part of the enemy force might be creeping up from the south for an end 

run. Spruance concluded that he had been misinterpreting the enemy’s intentions. 

He had first believed that the enemy would not oppose the invasion; then, on the 

basis of reported movements in the Philippines, he had changed his mind and begun 

to assume they would seek a fleet action. Now for a second time it seemed that he was 

wrong, and so informed Nimitz. In his view, the Japanese attitude toward striking the 

U.S. fleet had not changed but the method had—the enemy had started to use carriers for a fleet action. Spruance now believed that the Japanese intended to exploit any 

advantage that their carriers might gain: they did not intend to throw “everything at 

us by coming in to Saipan at high speed to fight it out.”130

Ozawa did indeed receive fairly accurate information on the composition and disposition of enemy forces near the Marianas.131 He also knew that enemy carriers had 

attacked Chichi Jima and Iwo Jima on the 15th and 16th and that the U.S. amphibious forces were supported by escort carriers. This meant that fast carriers would be 

freed of providing close support.132 Ozawa assumed that Spruance had learned of 

the Japanese concentration in the Philippine Sea. He also believed (as it turned out, 

correctly) that Spruance was a cautious commander and that his carriers would most 

likely remain within a few hundred miles of Saipan’s beaches.133 In other words, Spruance would remain on the defensive, covering Saipan instead of seeking a battle with 

the enemy carriers. However, Ozawa expected enemy forces to be diverted to attack 

Yap and Palau on 18 June. He received information from Tokyo that an enemy carrier 

group was off Guam, while the positions of other carrier groups were unknown. He 

believed that the enemy might engage the First Mobile Force as early as 18 June.134

Ozawa also received grossly inaccurate reports of successes by Japanese landbased aircraft against the invading forces. These reports claimed that one night 

fighter and five attack aircraft based on Truk had attacked a convoy of twenty 

ships four hundred miles from Truk and had sunk thirteen transports, leaving 

one destroyer listing heavily. A force of thirty-one fighters and nineteen bombers 

from Yap, he was similarly told, had attacked a force some thirty miles off Tinian and destroyed two or three carriers and left one destroyer or one transport 

burning.135
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At 2125, Admiral Nagumo sent a message that the enemy had conducted attacks 

every night since the landing but so far had been unsuccessful. The focus of the 

enemy attacks was Saipan’s Airfield No. 1. The enemy had landed three divisions 

on 17 June. Nagumo (correctly) estimated that the enemy would not land on Tinian and Guam for the time being but would focus on the initial phase of the Saipan 

landing. Probably, most of the enemy carriers had left the area. Nagumo advised 

not delaying the decisive encounter; otherwise the Japanese not only would miss 

an opportunity to inflict losses on the enemy fleet but would find it more difficult 

to resist the attack on Saipan.136

Between 13 and 17 June Spruance had had only a single report about Ozawa’s 

forces, and it had been obtained by a submarine. The submarine Cavalla had sighted at 2115 (some sources say 2245) on 17 June a large group of enemy ships at 

12° 23ʹ north, 132° 26ʹ east (some seven hundred miles west of Guam) zigzagging 

between courses 060° and 100°, with an estimated speed over the base course of 

nineteen knots (see map 14).137 The enemy force was composed of at least fifteen 

ships of combatant type. The formation was led by a carrier on the starboard flank, 

with two units of three vessels each—believed to be battleships or heavy cruisers—

in column on the port flank, plus more units.138 This was Ozawa’s force; Cavalla lost 

contact at dawn.139 Because of the darkness, Cavalla had been unable to observe all 

of Ozawa’s ships; also, Ozawa’s true position was some sixty miles northeast of the 

one reported.140 Nimitz believed that Cavalla’s report pertained to the main body 

of the First Striking Fleet; all traffic analysis indicated that this force was approaching the Marianas from the direction of the Philippines. There were indications that 

enemy land-based aircraft had flown searches from Palau, Yap, Mindanao, Formosa, Okinawa, southern Japan, Iwo Jima, Marcus, Truk, and possibly Woleai and 

Ulithi.141

Searching for the Enemy Forces, 18–19 June

During the night of 17–18 June, four Martin PBM seaplanes from Saipan searched 

for the Japanese fleet to a distance of six hundred miles but made no contact.142

Spruance was informed by Admiral Moore of Cavalla’s report in the early morning 

of the 18th. Spruance and Moore reassessed the situation in the light of this report. 

It seemed that the enemy fleet was rapidly converging on Saipan.143

Not until 0345 did Mitscher receive Cavalla’s report, sent at 2115 on the previous evening. He calculated that at nineteen knots the force should be about 660 

miles from Saipan at dawn and about five hundred miles from TF 58’s position 

at 0530. Hence, there would be little chance to detect it on 18 June. However, if 

TF 58 steamed directly toward the projected enemy position at 1500 it would be 

possible to detect it during the afternoon searches. Perhaps, Mitscher thought, if 

he maintained course and speed it would be possible to deliver a strike in late afternoon.144 At that time TGs 58.2 and 58.3 were too far east of Mitscher’s flagship 
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M A R I A N A S

Alamagan

Guguan

Sariguan

Anatahan

Medinilla

Saipan

Tinian

Aguijan

Rota

Guam 2400

17

0600

18

0300

19

0300

19

0630

18

contact lost

CAVALLA

1050 miles

STINGRAY

positions

real estimated

VAN

2030

18 HF-DF x

2000

CARDIVS 1.2

MAIN BODY 1900

1200

0115

19

radar

contact

by PBM 

2010

18

FINBACKsights search lights

105° 420 miles

#15

#17

PB4Y search from Los Negros

1200 miles Yap Feys Ulithi

195°-275°

325 miles

0530

18

PB4Y search from Los Negros

1175 miles

1330

185°-315° 18

325 miles 1430

1600

0200

19

PBM night search 18-19 June

600 miles

1330

1200

2400

TF 58

2030

sighting

sighting TGs 58.2, 58.3 rendezvous

0200

17

0800

18

2400

17

0530

18

2000

17

TG 58.4

from Iwo Jima

 TG 58.1 from Iwo Jima

50°

420 miles

1540

CHIYODA

launches planes

1637

1350°-110°

300 miles

600 miles

n MBP hgi est hcr a se 81 91- uJ enfalse sighting 75 miles north of this point

2346

18

142° 144° 146° 140° 138° 136° E 134°

18°16°14°12°10° N

134° 136° E 138° 142° 144° 146°

18°16°14°

12°

10° N

140° 

150 120 90 60 30 0

nautical miles

Japanese Main BodyJapanese Search PlanesU.S. Carrier Task GroupsU.S. Task Force 58U.S. Search Planes

Legend

Academics/jmo/2013/vego/BOPS/MAP5

MAP 5: MOVEMENTS AND SEARCHES OF THE OPPOSING FORCES, 17–19 JUNE 1944

Map 14

Movements and searches of 

the opposing forces, 17–19 

June 1944
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(Lexington); he planned a rendezvous for all four groups at 1200 on 18 June. 

Obviously, it would have been much better if they had assembled much earlier. 

However, this rendezvous could not be effected if TG 58.2 and TG 58.3 steamed 

southwest toward the oncoming enemy fleet. Because of the longer range of Japanese carrier aircraft, Ozawa would be able to strike these two groups before they 

could attack him. Mitscher’s option was to steam southwest and thereby extend 

TF 58’s afternoon searches to cover a larger area of possible enemy movements. 

This would perhaps bring the two carrier groups within striking range and would 

at least afford an opportunity of shadowing the enemy by night in preparation 

for operations the next day. Steaming southwest for a rendezvous would effect a 

concentration of forces and allow an afternoon search that would pick up the enemy if he continued at approximately his present speed. The decision was made 

to rendezvous to the southwest; the advantage was that it would place in striking 

position the concentrated air strength of TF 58 if the enemy launched a longrange attack.145

Mitscher believed that Cavalla’s contact was the enemy’s main body. He preferred that TF 58 steam at high speed toward the enemy, launch searches that 

afternoon to locate the enemy force, and then seek a surface engagement that 

night.146 This was the reason Mitscher asked Lee, “Do you desire night engagement? It may be we can make air contact late this afternoon and attack tonight. 

Otherwise we should retire to the eastward tonight. I am requesting task groups 

58.1 and 58.4 to join today.” Lee’s answer was firmly negative: “Do not repeat not 

believe we would seek night engagement. Possible advantages of radar more than 

offset with difficulties of communications and lack of training in fleet tactics at 

night. Would press pursuit of damaged or fleeing enemy, however, at any time.”147

Lee’s response reflected the reality that TG 58.7 could operate effectively as a cohesive force only in daylight. His task group had been formed from the ships of 

four other groups. Lee also believed that U.S. battleships were neither designed 

nor armed for close-range night actions against light forces. As he was to observe, 

“a few minutes intense fire . . . from secondary battery guns can, and did, render 

one of our new battleships deaf, dumb, blind, and impotent through destruction 

of radar, radio, and fire control circuits.”148

The fact was that neither Spruance nor Lee wanted the night engagement that 

Mitscher proposed. Mitscher’s numerical superiority made him stronger during 

daylight, while the danger of night melees favored the numerically weaker Japanese, who were better trained for them.149

At 0535, TGs 58.2 and 58.3 launched westward searches (between bearings 205°

and 285°) to a distance of 325 miles.150 At 0600 Japanese search aircraft detected six 

carriers sailing on a northeasterly course.151 U.S. carrier aircraft shot down one of 

them, a Jake seaplane launched by a cruiser. The episode indicated that the Japanese 
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were searching for the U.S. forces.152 At 0730, Cavalla sent another report, of a major part of the enemy fleet on course 080° at nineteen knots. It was then some 

seven hundred miles west of Saipan and closing.153 The track based on this report 

corresponded closely with that estimated earlier in the day. If Ozawa’s force continued on that course, U.S. air searches might detect it at some three hundred miles 

around 1530. That meant that if TF 58 decreased the range during the afternoon 

and night, and the enemy wanted to close and fight, a night surface action was 

quite possible.154 Back at Pearl Harbor, Vice Adm. John Towers, Commander, Air 

Force, Pacific Fleet, was concerned that Ozawa would enjoy a great advantage if he 

succeeded in positioning his force within six hundred miles of Guam, with TF 58 

in between. Ozawa would be then able to land his aircraft on Guam, to refuel and 

reattack. He urged Nimitz to direct Spruance farther west to seek out the enemy 

fleet. Nimitz rejected his advice, convinced that Spruance as the senior commander on the scene would know how best to employ the forces under his command. 

Nevertheless, he directed his chief of staff, Rear Adm. Charles McMorris, to warn 

Spruance about the possibility of shuttle bombing.155

Admiral Lockwood, after receiving Cavalla’s report, shifted four of his boats 

(Finback, Bang, Stingray, and Albacore, from what he called the “Pentathlon 

Group”), then patrolling northwest of Saipan, some 250 miles southward.156 Lockwood advised his commanding officers not to “miss any opportunity to get in a 

shot at the enemy.” Operating within a square, these four submarines would be 

athwart the track of the First Mobile Force.157 This proved to be an excellent decision and led to several critical sightings of Ozawa’s force. Lockwood also radioed 

to his submarines, “Now that contact with enemy forces has been made, shoot first 

and report later. Due to presence own surface forces, identify targets as enemy before firing.”158

In the morning on 18 June, however, Spruance was still largely in the dark regarding the exact location and composition of Ozawa’s force. He was relying largely 

on reports of submarines and search aircraft based in the Marshalls and Saipan. 

JICPOA’s radio intercepts were useful in reading messages transmitted by the Combined Fleet and other shore commands but not for obtaining precise information 

on the movement of the First Mobile Force, which had maintained strict radio 

silence since sortieing from Guimaras.

At 1200, TGs 58.1 and 58.4 joined TF 58; all four of Mitscher’s groups were now 

together. Thereafter until approximately 2000, TF 58 steamed on the course 245°

at fourteen knots. The need to turn to the east for all flight operations prevented 

a faster advance to the westward.159 At 1330, TGs 58.1, 58.2, and 58.3 launched 

searches out to 325 miles between 185° and 315°. The results of all the searches 

were negative. This meant that neither of the two enemy forces sighted by Cavalla

was yet within five hundred miles of Saipan.160
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For Spruance, Cavalla’s report about fifteen enemy ships reinforced his belief 

that Ozawa might try to outflank him. He knew from intelligence that Ozawa’s 

force consisted of at least forty surface combatants.161 There was no information on 

the whereabouts of the remaining ships. Also, Spruance disagreed with Mitscher’s 

assumption that the enemy would come from the southwest. He intended to stay 

near Saipan, searching westward by day and retiring eastward toward Saipan each 

night to prevent the Japanese from slipping past in the dark.162 Spruance sent an 

important message to Mitscher: 

TF 58 must cover Saipan and our forces engaged in that operation. I still feel that main enemy attack will come from westward but it might be diverted to come in from southwestward; 

diversionary attacks may come in from either flank or reinforcements might come from Empire [i.e., the home islands]. Consider that we can best cover Saipan by advancing westward 

during daylight and retiring eastward at night so as to reduce possibility of enemy passing 

us during darkness. Distance which you can make to westward during day will naturally 

be restricted by your air operations and by necessity to conserve fuel. We should however 

remain in air supporting position off Saipan until information on the enemy requires other 

action. Consider seeking night action undesirable initially in view of our superior strength 

of all types, but earliest possible strikes on enemy carriers is necessary.163

Spruance’s closing sentence was contradictory, in that Mitscher was unable to close 

the range with Ozawa’s force and at the same time stay close to Saipan. Also, on the 

morning of the 18th the wind was from the east. This was unfavorable to the U.S. 

carriers, because to steam into the wind for flight operations they had to turn away 

from the incoming enemy force, thereby opening, not closing, the range.164

Mitscher submitted an estimate that the enemy could be at 14° 00ʹ north, 142°

30ʹ east at 0400 on 19 June for an attack on the U.S. forces at Saipan. He proposed 

to proceed during the day to the westward conducting air searches to the maximum possible distance. He would reverse course toward Saipan at nightfall and 

stay within striking range of the enemy’s northern flank. If search reports were favorable, he would conduct a night-fighter and torpedo attack. Mitscher’s proposal 

was approved by Spruance.165

Ozawa, in the meantime, continued with his efforts to locate the enemy carriers. 

Between 1425 and 1540 one of his search planes detected three groups of carriers, 

one group of two regular carriers and ten to fifteen destroyers, the second group 

of two apparently regular carriers and other vessels, and the third with two regular 

carriers and ten other vessels.166 Ozawa did not want to attack so late in the day, because his pilots were inexperienced in the night flying.167 Nonetheless, he directed 

the 23rd Air Flotilla to attack and then land on Guam; however, its mission was 

subsequently aborted.168

Ozawa estimated that three enemy carrier groups were westward of the Marianas. There were no indications of the feared flank attack from the north. The range 

of U.S. scouting and attack aircraft, Ozawa knew, was about three hundred nautical miles; he (correctly) believed that because of the situation on Saipan the enemy 
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carrier force would most likely not move farther than that from the archipelago. 

Ozawa’s decision was to use all available aircraft on the day of decisive battle, 19 June. 

His intent was to “annihilate enemy regular carriers groups” advancing westward of 

the Marianas. The attack would be conducted from the south. The distance between 

the Japanese and enemy carriers would be about three hundred nautical miles, or 

480 if an attack were conducted on the enemy ships in the vicinity of the Marianas.169

Ozawa started to receive a stream of reports from his search aircraft. At 1514, 

search aircraft No. 15 reported, “Enemy task force, including carriers at 14° 50ʹ 

north, 142° 15ʹ east.” This was TF 58. At 1600, plane No. 13 also sighted enemy carriers. However, the most important sighting was by plane No. 17, searching south 

of No. 15, which sent reports shortly after 1600 of enemy carriers and other ships. 

At 1640, Ozawa had a more complete picture of the situation; the estimated position of the enemy carrier force was 14° 12ʹ north, 141° 55ʹ east. Plane No. 17 also 

reported that the enemy was on a westerly course and that the cloud cover was 

seven-tenths. The cloud layers were between 29,500 and 3,300 feet. The wind was 

easterly at eleven knots.170

At 1530, Ozawa received a report from plane No. 15 that led him to a decision to 

prepare for battle.171 Ten minutes later he ordered his force to change course from 

060° (east-northeast) to 200° (south-southwest). He wished to maintain a distance 

of no less than four hundred miles between his force and the enemy carriers, to retain the freedom of action offered by the longer range of his aircraft. At 1610, after 

receiving a report from No. 17 on an “unknown number of carriers, ten plus other 

ships” at 14° 12ʹ north, 141° 55ʹ east, Ozawa issued his Operation Order No. 16: 

“(1) At about 1500 enemy task force believed to be, one, 350 miles bearing about 

220° from Iwo Jima, and the other, 160 miles west of Saipan; (2) First Mobile Fleet 

will retire temporarily, after which it will proceed north and tomorrow morning 

contact and destroy the enemy to the north, after which it will attack and destroy 

the enemy to the northeast.” Unfortunately for the Japanese, however, neither of 

the reports on the location of TF 58 was accurate; at the time of No. 17’s contact (at 

1610), the center of TF 58 was actually about two hundred miles west of Saipan.172

Rear Adm. Sueo Obayashi, commander of CarDiv 3, prepared his three carriers 

to launch some sixty-seven aircraft at 1637. Three Jills, fifteen Zeros armed with 

bombs, and four Zero fighters had been launched when he received Order No. 16 

from Ozawa. At 1710, No. 17 search plane sent another and more detailed report: 

the enemy force consisted of two small groups, one composed of two Saratoga-class 

carriers and ten to fifteen destroyers, and a second comprising two regular carriers 

and ten or more other ships. The enemy ships were on an easterly course. Within 

the next hour Ozawa received from Tokyo a warning that the report that the enemy 

force was “350 miles, bearing 220° from Iwo Jima” was false. Hence at 1817, Ozawa 

issued Operation Order No. 19, stating that the enemy force west of the Marianas 
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(as reported by search plane No. 17) would be the main target of attack on the 

19th.173 This led Obayashi to recall his aircraft. Junior commanders were not happy 

with Ozawa’s decision not to attack immediately. They believed that a strike even so 

late in the day would be successful, because it would have a good chance of achieving surprise. Also, the attacking planes would be able to land on Guam.174

While CarDiv 3 recovered its planes, the main body steamed on course 200°. At 

1900 it changed course to 140° and slowed to sixteen knots. At 2020 Ozawa broke 

radio silence for the first time; he had to tell Kakuta where TF 58 could be found 

and arrange for coordinated attacks on the next day. A U.S. naval DF station picked 

up that message, though it lasted only a few minutes, and identified it as having 

been sent by Ozawa. The station estimated Ozawa’s position as 13° north, 136° east 

(its actual position at that time was only some forty miles away). TF 58 was some 

three hundred miles from that point. The DF station reported by message.175

By 18 June, Japanese land-based aircraft in the Marianas had been decimated by 

TF 58’s strikes. Admiral Kakuta, who was on Tinian, ordered all nineteen remaining aircraft (including fifteen Zero fighters) on Truk to move to Guam by the early 

morning of the 19th. They did so just in time to escape a fifty-six-aircraft strike 

by U.S. Army Air Forces Liberators based on Los Negros and Kwajalein. These 

last-minute reinforcements brought the number of planes of all types on Saipan to 

about fifty, compared with the five hundred envisaged in the original A-Go operation plan.176

Spruance’s Decision

In the meantime, at 2000 on 18 June, TF 58 changed course to the eastward.177 During the evening Spruance’s staff continued to discuss the possible courses of action. 

Some members agreed with Spruance, while others supported Mitscher’s desire to 

continue westward.178 Spruance felt that until he knew about all the elements of the 

enemy fleet he could not leave Saipan unprotected either to attack or to search for 

the enemy.179 He reportedly said, “I believe that making a war is a game that requires 

cold and careful calculation.” In his view, “it might be a very serious thing if we 

turned the wrong way, just once.”180 At 2130, Spruance decided to stay near Saipan 

and let the enemy come to him. TF 58 would then sink the enemy carriers before 

they could sink transports.181

It was at 2200 that Spruance received from Nimitz the information that a radio 

transmission apparently from CINC, First Mobile Fleet had been “DF’ed” within a 

hundred miles of 13° north, 136° east at 2023. This position was some 585 miles 

and 257° from Saipan.182 Nimitz’s information meant that the enemy force was between 11° 30ʹ north and 15° 30ʹ north and not farther east than 138° (see map 

14). At 2346, a message from Admiral Lockwood (not addressed to Spruance but 

monitored on the fleet broadcast) stated that he was unable to read a message from 

the submarine Stingray because of jamming. Stingray’s position was then 12° 20ʹ
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Spruance’s Decision at 0038, 19 June 

Spruance made a tough decision in the early morning of 19 June to adhere to his original mission by not 

risking movement too far westward from Saipan. In his war diary Spruance gave the following six reasons 

not to turn west at 0038 on the 19th: 

• The DF fix given for the Japanese force was not definite, being somewhere within a hundred-mile 

radius. 

• The originator of the transmission was not definitely known. 

• The size and composition of the enemy force was not known. 

• It was important to guard against a flanking movement.

• The transmission could be from a decoy. 

• A transmission from the submarine Stingray had been jammed at 2346, indicating that it might be in 

contact 175 miles east-southeast of the DF fix.1

Spruance’s primary mission was to capture Saipan, Tinian, and Guam. The amphibious landing on 

Saipan was at that time at the critical stage. The troops ashore had only part of their supplies; the remainder was on board a large number of ships in the vicinity of Saipan. The Japanese had usually divided their 

forces and approached from different directions; they had done that in the battles of the Coral Sea and 

Midway, and at Guadalcanal. The Japanese Z operation plan indicated that this was still their doctrine. The 

sightings so far received showed Spruance that two separate forces were definitely approaching. He did 

not know whether they had joined. Spruance was eager for an all-out battle but was determined not to 

take his carrier striking force beyond supporting distance of the beaches unless he was sure that no end 

run around his flank was planned. He would not be lured away from what he conceived to be his main job 

of protecting the landing force.2

After the war, Spruance revealed his reasoning. In 1952, he would write in a letter that “as a matter of 

tactics—I think that going after the Japanese and knocking their carriers out would have been much better and more satisfactory than waiting for them to attack us; but we were at the start of very important 

and large amphibious operation and we could not afford to gamble and place it in jeopardy. The way Togo 

waited at Tsushima has always been in my mind. We had somewhat the same basic situation, only it was 

modified by the long range striking power of the carriers.”3

Spruance in the postwar years asked himself what he would have done had he been a Japanese commander. He felt that he had known in 1944 the Japanese way of thinking, after his years of study and his 

friendships with Japanese naval officers. By this logic he was convinced by mid-evening of 18 June that the 

Japanese were capable of a flanking movement to hit the transports and that in fact they would do exactly 

that. Apparently, Spruance did not seriously believe that the Japanese might be going after Mitscher’s 

carriers rather than Admiral Turner’s transports. If the Japanese admiral had not divided his forces but 

sought the carriers rather than the transports, Spruance’s revised battle plan would have been potentially 

disastrous. It would have exposed U.S. carriers to a long-range attack, and they would have been unable, 

with their shorter-range aircraft, to retaliate.4

Nimitz stoutly defended Spruance’s decision and actions in the battle of the Philippine Sea:

It may be argued that the Japanese never had any intention of evading Task Force 58 with part or all of their forces, 

and aiming their major air attack against our shipping at Saipan. From this premise it could be proved that our main 

body of carriers and gunnery ships could have pushed them to westward without concern for expeditionary forces, 

and that had it done so, a decisive fleet air action could have been fought, the Jap fleet destroyed, and the ending 

of the war hastened. There is no restriction in surmising how a hand might have been played and how much could 

have been won had the cards fallen differently from the way they did.5

1. Forrestel, Admiral Raymond A. Spruance, p. 137.

2. Ibid., p. 138.

3. Potter, Nimitz, p. 302; Taylor, Magnificent Mitscher, p. 239.

4. Buell, Quiet Warrior, p. 293.

5. Taylor, Magnificent Mitscher, pp. 239–40.
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Nevertheless some complaints from Nimitz’s staff aviators crept into his summary for June 1944: “There 

may be disappointment to some. In fact, that in addition to the successful accomplishment of our 

purpose—the occupation of the southern Marianas—there was not also a decisive ‘fleet action’ in which 

we would naturally hope to have been victorious and to have thereby shortened the war materially.”6

Admiral King, upon arriving at Saipan for a meeting about 12 July 1944, told Spruance that he had 

done exactly the correct thing with the Fifth Fleet in the Philippine Sea, whatever others might say, because the Japanese had had another fleet, in the Inland Sea, ready to fall on the many U.S. transports that 

had not discharged their cargoes at Saipan.7 King elsewhere defended Spruance’s decision by arguing, “As 

the primary mission of the American forces in the area was to capture the Marianas . . . the Saipan amphibious operation had to be protected from enemy interference at all costs. In his plans for what developed 

into the battle of the Philippine Sea, Spruance was rightly guided by this basic obligation.”8

Spruance’s decision nonetheless remained highly controversial. It was not well received at the time 

by Mitscher’s staff, especially his chief of staff, Commodore Arleigh Burke (1901–96, later an admiral and 

CNO). Burke and his operations officer, Cdr. John “Jimmie” S. Thach, drafted one scorching message after 

another, in what amounted almost to mutiny. Yet eventually they too accepted that it was Spruance’s call 

and gave up hope of changing the decision and letting TF 58 move westward.9 There remained among 

the naval aviators, however, little doubt that Spruance had missed the opportunity of the century. A common complaint was that this is what could be expected when a nonaviator was put in charge of carriers.10

For example, Adm. Frederick C. Sherman (1888–1957), a highly regarded aviator and carrier group commander, was a particular critic of Spruance’s handling of TF 58. He would assert that Spruance’s order that 

TF 58 was to head east during the night conflicted with his “Beware of an end run.” Spruance, he believed, 

“was still thinking in terms of surface action. He did not grasp the tremendous power of our air weapons 

or their ability to strike in any direction to the limit of their fuel. There were no end runs in aerial warfare.”11

Some claimed that if Spruance had changed his mission from covering Saipan to seeking out and destroying the enemy fleet, the gain might have been worth the increased risk. If successful, he would have 

eliminated a major threat to future U.S. operations and possibly have shortened the war, as against the 

risk of losing a few transports and a concomitant delay in seizing Saipan. Nimitz’s explicit message the day 

before urging a decisive victory in the possible fleet action was, in this view, more than enough justification for Spruance to modify his original mission of covering Saipan regardless of the tactical situation.12

Spruance could in fact have alleviated the risk of uncovering Saipan. Turner had seven old battleships 

and eleven escort carriers, with which he could have fought a delaying action against an end run while TF 

58 engaged the enemy carriers to the westward. Immediately after that engagement, TF 58 could have returned to Saipan at high speed—into the wind, conducting air operations as it steamed—quickly closing 

the range to Saipan, ideally before the enemy could inflict unacceptable damage there. However, this option had several drawbacks. The escort carriers were slow and could be easily outmaneuvered by the fast, 

heavy Japanese surface ships. The U.S. old battleships were armed primarily by high-explosive projectiles 

meant for shore bombardment. They carried only a limited supply of armor-piercing projectiles, which 

were best suited for surface engagement. The escort carriers carried few if any torpedoes, and their bombs 

were of the high-explosive type, for support of troops ashore.13 There was also a possibility that the enemy 

did not plan an end run and would refuse battle. Reportedly, all these courses of action were discussed 

and examined by Spruance and his staff throughout the day and early evening of 18 June.14

In the end, Spruance stuck to his mission but in so doing risked extensive losses to his carrier forces. He 

did not allow TF 58 to attack the Japanese carriers on 19 June but instead opted to absorb the full impact 

of the enemy’s air attack. On the night of 18–19 June he denied the carriers of TF 58 the sea room they 

6. Potter, Nimitz, p. 303.

7. Y’Blood, Red Sun Setting, p. 206, cited in Taylor, Magnificent Mitscher, p. 238.

8. Potter, Nimitz, p. 303.

9. Tillman, Clash of the Carriers, p. 101.

10. Potter, Nimitz, p. 303.

11. Taylor, Magnificent Mitscher, p. 239.

12. Buell, Quiet Warrior, p. 294.

13. Ibid.

14. Ibid., p. 295.
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needed for prolonged flight operations. The carriers had to steam toward Guam throughout the day while 

launching and recovering; more than one carrier had to delay flight operations to dodge islands. Such a 

tactical handicap earlier in the war would have been fatal. The Japanese pilots of 1944, however, were 

no match for the superb fighter pilots the U.S. Navy had by then produced; Spruance was very lucky that 

Mitscher’s pilots were able to overcome these deliberately accepted constraints.15

Spruance had made a similar decision during the invasion of the Gilberts in November 1943 (Operation GALVANIC). His inherent caution then led him to restrict carrier activities to an area around the islands. 

This lack of mobility unnecessarily exposed carrier groups to air and submarine attacks, in which they 

suffered unwarranted damage. The carrier Independence was torpedoed and put out of action for several 

months. The carriers would have been more effective if they had been allowed to attack the enemy positions in the Marshalls.16

Spruance returned to Saipan on 18–19 June because he believed that transports would be needed 

there the next day. But they were not needed.17 The transports were, in fact, about two hundred miles east 

of Saipan, and completely out of danger. Unbeknownst to Spruance, Gen. Holland M. Smith did not think 

he would need the transports for the two days the fleet battle would take.18 General Smith felt that his position ashore was not bad. All his artillery had been landed, and this partially compensated for the lack of 

naval gunfire. Spruance, then, could have ordered the transports to safe haven in the east without unduly 

endangering operations ashore. The fleet action would have been decided within a day; the U.S. troops 

on Saipan could have held their own for that long, even if they had been forced to delay their advance.19

But the question here is what was known to Spruance at that time. In deliberating whether to close the 

enemy fleet on the night of 18–19 June he would have been prudent to reconsider his assumptions made 

two and a half days earlier. The relevant question that night, in retrospect, was whether all the transports 

could be moved eastward for from twenty-four to thirty-six hours to allow TF 58 time for a decisive action. 

Yet Spruance never suggested such a course of action to Turner. Nor did Turner volunteer to clear to the 

east so as to free Spruance to advance toward the enemy. The universal assumption was that Turner had 

to return some transports to Saipan on 19 June.20

The most ironic aspect of the situation was that Spruance thought that he could “read” the enemy side 

and make decisions on that basis. Yet time and again he analyzed his counterpart’s intentions wrongly. In 

contrast, Ozawa correctly predicted both Spruance’s state of mind and his intentions.21 Spruance assumed 

Ozawa would split his forces and attack Turner’s transports, but Ozawa did just the opposite. Ozawa assumed that Spruance would cautiously remain near Saipan, allowing him, Ozawa, to launch long-range 

strikes without risk to his carriers. Ozawa, who had only nine carriers versus the fifteen of TF 58, could 

count on help from land-based aircraft at Guam, Rota, and Yap. However, his plan was fatally undercut by 

the poor state of training of his pilots; in any case, the majority of the Japanese land-based aircraft were 

destroyed before Ozawa’s force arrived within striking range of the Marianas.22

Clearly, Spruance was unduly concerned with the possibility of attack from the flank. He had read the 

Z plan and was convinced that the Japanese would go after Turner’s transports. Yet his confidence in his 

ability to divine his opponent’s intentions was misplaced; Ozawa was much more skillful in guessing what 

Spruance would do and in planning accordingly. The Japanese were in fact still seeking a decisive battle 

with the U.S. Pacific Fleet; the transports were secondary.23

Another problem was that Spruance’s staff was almost entirely composed of surface officers, like Spruance himself. Admiral Burke believed that this reflected a fundamental weakness in Spruance as a commander. In Burke’s view, a little healthy disagreement from people with different outlooks might have 

15. Ibid., pp. 300–301.

16. Y’Blood, Red Sun Setting, p. 204.

17. Buell, Quiet Warrior, p. 301.

18. Cited in Y’Blood, Red Sun Setting, p. 206.

19. Buell, Quiet Warrior, p. 301.

20. Ibid., p. 302.

21. Ibid.

22. Ibid., p. 303.

23. Y’Blood, Red Sun Setting, p. 206.
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north, 139° 00ʹ east, about 435 miles and west of Saipan.183 The jammed transmission indicated that the enemy force might be at approximately 12° 20ʹ north, 139°

00ʹ east, at around 2300.184 Nimitz’s and Stingray’s messages together indicated to 

Spruance a probable movement of the enemy force to the eastward, but neither 

was conclusive about its position.185 From Spruance’s perspective, “it was not clear 

whether the enemy force was concentrated, or in two or more groups, whether the 

enemy was advancing directly toward Saipan, delaying his movement eastward or 

moving his forces to within striking distance of Saipan by the northern flank, the 

southern flank, or both.”186

About thirty minutes before midnight, Mitscher called Spruance on the TBS 

(talk between ships) circuit and proposed to change course to 270° at 0130 to be 

able to launch an attack at 0500. Did Spruance agree?187 Spruance studied and 

discussed the situation with his staff for about an hour and at 0038 on the 19th 

rejected the proposal, sending the following message to Mitscher: “Change proposed does not appear advisable. Believe indications given to Stingray more accurate than that determined by direction finder. If that is so continuation as at 

present seems preferable. End run by other carrier groups remains possibility and 

must not be overlooked.”188 (For details of Spruance’s decision and the views of 

critics, see the sidebar “Spruance’s Decision at 0038, 19 June.”)

Clash of the Carrier Forces, 19–20 June

By the midnight of 18–19 June, Ozawa had fairly complete knowledge of the 

location and movements of Spruance’s Fifth Fleet. He called heavily on landbased search planes for information, yet all that he received was from aircraft of 

his carriers and floatplanes from his cruisers. On 18 June Ozawa learned from 

them about the carriers at TF 58’s northern and southern edges, about forty miles 

apart. This information gave Ozawa a good fix on TF 58.189 At 0008 on the 19th he 

sent a message to his fleet: “I humbly relay the message which has been received 

from the Emperor through the chief of staff, the IGHQ’s Naval Section. ‘This 

operation has immense bearing on the fate of the Empire. It is hoped that the 

force will exert their utmost and achieve as magnificent results as in the battle of 

Tsushima.’”190

24. Ibid., p. 205.

25. David M. Abshire, “The Inimitable Admiral Arleigh ‘31 Knots’ Burke: Lessons for Leadership and Strategy Today” 

(Abshire Lecture in Honor of Admiral Arleigh Burke, Center for Strategic and International Studies, Washington, D.C., 

29 January 2010), p. 10, available at www.thepresidency.org/; Taylor, Magnificent Mitscher, p. 237.

been beneficial.24 Burke believed too that Spruance did not, after the exchange of carrier strikes, aggressively pursue the Japanese fleet but instead opted to play it safe and protect the invasion fleet. Burke’s 

draft after-action report criticized Spruance on this point. Mitscher disagreed, and Burke rewrote the report, but it remained critical of Spruance’s decision. Mitscher’s own after-action report included the following: “The enemy has escaped. He had been badly hurt by one aggressive carrier air strike, at the one time 

when he was within range. His fleet was not sunk.”25
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At midnight TF 58 was at a position 14° 27ʹ north, 142° 05ʹ east, on course 009°

and at a speed of seventeen knots. Spruance’s intent was to proceed on that course 

until 0620 so as to be close to Saipan. He wanted to be within supporting distance 

of the troops ashore in case the enemy force came within striking distance from 

either north or south.191

At 0115, a long-range PBM from Saipan obtained a radar fix on forty enemy 

ships in two groups about seventy-five miles northeast of Nimitz’s DF fix of the 

preceding evening (see map 15). This critical piece of information did not reach 

Spruance for eight hours. Otherwise, perhaps it would have influenced him to turn 

westward to reduce the gap of three hundred miles before morning.192

At 0150 Spruance received a report from the submarine Finback that it had 

sighted searchlights at 14° 25ʹ north, 135° 45ʹ east at 2010 on 18 June (see map 14). 

That position was about a hundred miles northeast of the DF fix sent by Nimitz.193

Finback also reported seeing numerous unidentified aircraft during the day of the 

18th. This report only further reinforced Spruance’s resolution to continue eastward. He was now convinced that the enemy had been generally aware of the location of TF 58 on 18 June.194

At 0300, Ozawa’s force changed its course to 050° and increased speed to twenty 

knots.195 Between 0300 and 0400 Ozawa reorganized his battle formation into three 

groups: Force A (Ozawa, CarDiv 1); Force B (Rear Adm. Takaji Joshima, CarDiv 

2), and Force C (Rear Adm. Takeo Kurita, CarDiv 3). Forces A and B constituted 

the main body, five fast carriers and one light carrier. They were arranged about 

nine miles from each other (see figure 1). Force C, or the van, consisted of three 

circular groups sailing in a line abreast about six miles from each other. The most 

powerful surface combatants were in Force C; each of its groups included battleships and heavy cruisers and was centered on a light carrier. Force C was about a 

hundred miles ahead of the main body. Ozawa’s aim in devising such an unusual 

cruising formation was to inflict heavy losses on incoming enemy aircraft. They 

would be forced to fly through the intensive AA defenses of Force C, fly another 

hundred miles to the main body and then a hundred miles back, and again pass 

over strong AA defenses returning to their carriers. In his view, the Americans 

would suffer catastrophic losses in such attacks. If the U.S. carrier forces advanced 

westward to bring their aircraft within range of the First Mobile Force, they might 

sink some Japanese carriers, but Ozawa would have a better chance of sinking more 

of the enemy’s.196 This battle disposition was very different from the one practiced 

by the U.S. Navy. Among other things, it allowed the optimum use of cruiser and 

battleship floatplanes for search. It also placed the three smaller, converted carriers within powerful AA defenses so that they could absorb any enemy attack and 

protect the six larger carriers.197 A great disadvantage was that Ozawa’s carriers were 

poorly protected from attack by submarines.198
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Alamagan

Guguan

Sariguan

Anatahan

Saipan

Tinian

Aguijan

Rota

Guam

CARRIER

PLANE

SEARCHES

0945 sighting

0922

2400

18 0200 19

0600

19

2400

19

1023 1200

1330

2000

TF 58

TG 58.4

1000 sighting

0730

sighting

0700

0530 20°-105°

560 miles

1330 185°-345°

325 miles

0600 185°-345°

325 miles

1100 miles

PB4Y search from Los Negros

PB4Y search f om r Los Neg os r

1170 miles 0115

radar

contact by PBM

PB4Y sighting of two carriers

1120

19

0445 315°-135°

350 miles

VAN-CARDIV 3

1200 0800 1030

0445

0807

CARDIV 2

CARDIV 1

0905

0530

15321430 1300

CARDIV 1

CARDIV 2

1100 miles

142° 144° 146° 140° E 136°

18°16° N14°12°

136° 138° 142° 144° 146°

18°

16° N

14°

12°

140° E 

Japanese 

Main Body

Japanese Search PlanesU.S. 

Carrier

Task Groups

U.S. Search Planes

Legend

120 60 30 0

nautical miles

90

Academics/jmo/2013/vego/BOPS/

Map6

MAP 6: 

M

OVEMEN

TS OF OPPOSING FORCES AND SEARCHES, 19 JUNE 1944

Map 15

Final approach, 19 June 

1944
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Figure 1

First Mobile Force: Battle 

Disposition #1 (MOD), 

19 June 1944

Figure 1: FIRST MOBILE FORCE: BATTLE DISPOSITION #1(MOD), 19 JUNE 1944

100 MILES

KONGO

HARUNA

CHOKAI CHIYODA

YAMATO

NOSHIRO MAYA

SUZUYA

TONE

CHIKUMA ATAGO

KUMANO

CHITOSE

TAKAO

MUSASHI

VANGUARD

3 CVL4 BB8 CA1 CL8 DD

10 Km

LEGEND

AIRCRAFT CARRIERBATTLESHIP or CRUISERDESTROYERFLAGSHIP FORCE A (OZAWA) 3 CV

2 CA1 CL7 DD

FORCE B (JOSHIMA)

2 CV1 CVL1 BB1 CA8 DD MAIN

BODY

9.3 Miles

MOGAMI

NAGATO HIYO

JUNYO

RYUHO

MYOKO

YAHAGI

HAGURO TAIH

Ō

ZUIKAKU

SH

ŌKAKU

FORCE C (KURITA)

Academics/jmo/2013/vego/june/Figure1

COURSE and AXIS

050o

6.2 Miles

6.2 Miles
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In the early morning, Ozawa made a determined effort to locate the enemy carrier groups precisely. At 0330 he launched a first wave of search planes (sixteen 

Kate seaplanes); at 0415 a second wave (thirteen Kates from CarDiv 3 and one Jake 

seaplane from Chikuma) was launched.199 (This wave sighted only destroyers, and 

seven of its planes were shot down by TF 58’s dawn search aircraft.)200 At 0530, a 

third wave of search planes (eleven Judys from Shōkaku and two seaplanes from 

Mogami) was launched from 12° 20ʹ north, 136° 35ʹ east.201 They were to search out 

to 560 miles.202 By 0600 Ozawa had more than sixty aircraft searching for the enemy 

carriers; other planes were being readied for attack. Hence, only a few aircraft were 

available for CAP. Also, antisubmarine patrols were called off—this proved a costly 

mistake.203

At 0634, Ozawa’s No. 7 search plane from the first wave reported sighting, about 

160 miles west of Saipan, two regular carriers, four battleships, ten cruisers, and 

some old vessels—tracked collectively as “objective [i.e., contact] 7 I”—heading 

west. Shortly afterward, Ozawa received a report of four other enemy regular 

carriers.204 By 0700 the planes of Ozawa’s first wave had reached the limits of 

their searches and started their return. One plane on its return leg sighted about 

0730 parts of the enemy carrier striking force (actually TG 58.4 and TG 58.7, or 

“objective 7 I”).205

TF 58’s own searches at 0200 and 0530 were as fruitless as were those of the 

preceding day.206 At 0200 the carrier Enterprise launched a search-and-attack group 

of fourteen torpedo planes to cover the sector between 240° and 270° out to three 

hundred miles. At 0530, TF 58 launched another search between 185° and 345° and 

to a distance of 325 miles from 14° 40ʹ north, 143° 40ʹ east. This search had negative results. However, its aircraft shot down one Japanese aircraft thirty-seven miles 

from the task force at 0554.207

Until about 0530, TF 58 continued on a northeasterly course, but then it turned 

to the southwest, directly into the wind. The centers of the carrier groups were 

twelve to fifteen miles apart. The ships of each group were deployed in four-milediameter circles (see figure 2).208 The weather was clear and warm. There were only 

a few clouds. The wind was from the east-northeast to east-southeast at between 

nine and twelve knots. Ceiling and visibility were unlimited. From the bridge of a 

carrier it was possible to see up to forty miles.209

At 0620, Spruance directed TF 58 to change course to the west-southwest, 250°, 

at fifteen knots to close the distance with the still-undetected enemy force. By then 

TF 58 had reached 14° 37ʹ north, 143° 58ʹ east.210 However, TF 58 could not steam 

on that westerly course for long, because of the need to turn into the wind to operate aircraft. As it happened, the carriers had to change course four times (at 0706, 

0741, 0800, and 0830). By 1023 they were only a few miles farther westward than 

they had been at daybreak.211
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Figure 2: TF58’s BATTLE FORMATION, 19 JUNE 1944 LEGEND CARRIER BATTLESHIP CRUISER DESTROYER COWPENS ESSEX LANGLEY BATAAN BELLEAU WOOD HORNET YORKTOWN TG 58.4 (HARRILL) 1 CV 2 CVL 3 CL, 1 CLAA 14 DD CRUISERS: SAN DIEGO, VINCENNES, HOUSTON, MIAMI TG 58.1 (CLARK) 2 CV 2 CVL 3 CA 1 CLAA 14 DD CRUISERS: OAKLAND, BOSTON BALTIMORE, CANBERRA TG 58.3 (REEVES) 2 CV 2 CVL 1 CA 1 CLAA 3 CL 13 DD CRUISERS: RENO, MONTPELIER, INDIANAPOLIS, CLEVELAND, BIRMINGHAM TG 58.2 (MONTGOMERY) 2 CV 2 CVL 3 CL, 1 CLAA 12 DD CRUISERS: SAN JUAN, MOBILE, BILOXI, SANTA FE TG 58.7 (LEE) 7 BB 4 CA 11 DD BATTLESHIPS: INDIANA, IOWA, NEW JERSEY, ALABAMA, WASHINGTON, SOUTH DAKOTA, NORTH CAROLINA CRUISERS: NEW ORLEANS, WICHITA, MINNEAPOLIS, SAN FRANCISCO PICKET DESTROYERS (TG 58.7) YARNALL, STOCKHAM ENTERPRISE PRINCETON SANJACINTO LEXINGTON WASP MONTEREY BUNKERHILL CABOT 20 miles AXIS 090o 15 miles12 miles

12 miles 12 miles

Academics/jmo/2013/vego/june/Figure2

Figure 2

TF 58’s battle formation, 

19 June 1944
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Spruance told Mitscher that if the morning searches failed to find enemy ships, 

neutralization strikes on Guam and Rota would be necessary. Mitscher’s response 

was that this would not do any good, because of the lack of proper bombs, but that 

he would keep Guam under fighter surveillance.212 At 0715, Mitscher was informed 

that fighter aircraft from the carrier Belleau Wood (in TG 58.1) had observed many 

enemy aircraft taking off from Guam and had shot down ten of the fifteen fighters. 

This was why Mitscher ordered a sweep over Guam by fighters of the three carrier 

groups.213

In the meantime, Ozawa had directed that a series of massive air attacks on TF 

58 start at 0730 (see map 16). CarDiv 1 launched its first attack wave of 129 aircraft 

(fifty-four bombers, twenty-seven carrier attack planes, and forty-eight land-based 

attack planes) against “objective 7 I,” some 380 miles away. At about 0830, CarDiv 

3, of Force C, launched sixty-nine planes (sixteen Zero fighters, forty-five Zero 

fighters armed with bombs, and eight Jill torpedo bombers) against the same objective.214 Mitscher’s flagship, the carrier Lexington, was then about 110 miles away 

and southwest of Saipan.215

At 0820 a search plane from CarDiv 3 detected a large enemy force including 

battleships. At 0845 search plane No. 15 of the third search wave detected three large 

enemy carriers, five battleships, and ten other smaller ships (collectively designated 

“objective 15 Ri”) about seventy nautical miles southwest of Guam on course 240°. 

At 0900 forty-nine aircraft of CarDiv 2’s first attack wave (twenty-six land-based 

fighters, sixteen fighters, and seven attack aircraft), heading to attack “objective 7 I,” 

were directed to change their course at 0930 and attack “objective 3 Ri.”216

The Japanese suffered a major blow at about 0910 when the submarine Albacore

torpedoed Ozawa’s flagship, the 37,870-ton carrier Taihō, in Force A, at 12° 24ʹ

north, 137° 20ʹ east.217 All but one of Albacore’s six (by some accounts four) torpedoes missed, because of a faulty torpedo-fire director. The one hit struck Taihō 

just after it launched forty-two aircraft as part of Ozawa’s second attack wave, led 

by CarDiv 1.

At about 1000, TF 58 radars detected many enemy planes to the westward at 

about 150 miles.218 (Other sources say 130 miles.)219 At 1005, the first of a series of 

large “bogies” (enemy aircraft or groups of them) was picked up bearing 265°, distant about 125 miles, at an altitude of twenty-four thousand feet. Mitscher recalled 

all his fighters that were bound for Guam. A search-and-attack group was sent to 

the westward, but it failed to detect the enemy ships.220 At 1010 Mitscher ordered 

TF 58 to prepare to launch every available fighter plane. About ten minutes later 

he gave the order, “Execute.” At 1023 the enemy planes were only about 110 miles 

from Lexington. The entirety of Task Force 58 changed course to the east and into 

the wind.221 All the U.S. fighters were launched between 1023 and 1038. The carriers’ decks were cleared of bombers so as to keep fighters in the air continuously.222 
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Tinian Aguijan Rota Guam

CarDiv 1

CarDiv 2

CarDiv 3

CarDiv 2

CarDiv 1 0530

0530

0300

0905

0910

Taihō hit

by ALBACORE

by CAVALLA

Shōkaku sunk

Shōkaku hit

1130

1501

Taihō sunk

1532

1000

1130

0807

1030

0530

0430

0830

1200

VAN

3rd Attack

2nd Attack

1st Attack

4th Attack

(CarDiv 2)

(CarDiv 1)

15 RI

air battle

and

interceptions 0720–1825

1st interception 

2nd interception

3rd interception

4th interception

1036

1139

1421

1300

2000

0600

0200

7I

Orote

1330

1023

TF 58

3 Ri

142° 144° 140°E 138°

16°14°12°

138° 142° 144°

16°

14°N

12°

140°E 

Track of Japanese FleetTrack of Flagship, TF 58Approximate attack routes of Japanese planesInterceptions. (Times of Interceptions are timeswhen they began).Approximate attack routes of U.S. planes

Legend

90 60 0

nautical miles

120 30

Academics/jmo/2013/vego/BOPS/MAP7

MAP 7: THE CLIMAX, 0300–1500, 19 JUNE 1944

Map 16

The climax, 0300–1500, 

19 June 1944
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Because the wind, as noted, was only nine to twelve knots, the carriers had to 

steam at twenty knots to attain the thirty-knot wind over the flight deck needed for 

launching and recovering aircraft.223 They also had to conduct zigzagging maneuvers. Hence, as before, they gained little ground to the westward to close the range 

with the enemy carriers.224

Japanese aircraft were intercepted thirty-five or forty miles west of TG 58.7. 

These were the sixteen Zero fighters, forty-five Zeros carrying bombs, and eight Jill 

torpedo bombers of the first attack wave launched from Force B.225 Some seventy 

Hellcats intercepted them.226 Meanwhile, Ozawa decided that after the end of the 

first attack, if enemy losses had been heavy, the First Mobile Force would advance 

to the Marianas at dawn on 20 June and resume the air battle; a diversionary force 

would annihilate the enemy. In the event that the losses inflicted by the first attack 

wave were inconsiderable, the First Mobile Force would temporarily retreat westward, reorganize and refuel, and then try to force a decisive battle.227

Ozawa’s second attack wave was launched at 0856, consisting of 138 aircraft 

(fifty-three Judy bombers, twenty-seven Jill torpedo bombers, and fifty-eight Zero 

fighters). These planes encountered difficulties on the way to their intended targets. Because of engine troubles, eight had to return to their carriers shortly after being launched. The remaining 130 planes flew by mistake over Force C; two 

planes were shot down and eight were damaged by the AA fire of Kurita’s ships.228

At 1107 TF 58’s radar detected these planes at about 115 miles out; U.S. fighters 

intercepted them when they had approached TF 58 to about sixty miles.229 At 1145, 

about twenty planes of this group broke through; TG 58.2 was subjected to two 

large attacks and TG 58.3 to one.230 The Japanese aircraft attacked also the battleships South Dakota, Alabama, Indiana, and Iowa of TG 58.7 and the carriers Wasp

and Bunker Hill of TG 58.2. Other Japanese bombers attacked Enterprise (at 1157) 

and Princeton (at 1202) of TG 58.3. Only thirty-one Japanese aircraft returned to 

their carriers.231 During the attack on TG 58.7 the new battleship South Dakota

sustained a direct hit, and the heavy cruiser Minneapolis suffered a near miss. An 

enemy plane crashed into the side of the battleship Indiana. The carriers Bunker 

Hill and Wasp had near misses.232

During the air battle, a few aircraft from Lexington patrolled the Guam area. 

At about 1040, the carrier Hornet sent seventeen Helldivers and seven Avengers, 

escorted by twelve Hellcats, to bomb the Orote field on Guam. They encountered 

no opposition in the air.233

At about 1000, the third attack wave of sixty-four aircraft (twenty-six fighters, 

thirty-six carrier bombers, and two carrier bombers) was launched from CarDiv 2, 

Force B.234 (One historian claims that the third attack wave, launched between 1000 

and 1015, involved forty-seven aircraft—fifteen Zeros, twenty-five Zeros armed 

with bombs, and seven Jill torpedo bombers.)235 These Japanese planes approached 
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TF 58 from the north. The Japanese planes were detected at a distance of about a 

hundred miles by radars of TG 58.1, and some forty Hellcats were sent to intercept 

them. Seven attackers were shot down; the rest of the third attack wave returned 

safely to their carriers.236

In the aftermath of Ozawa’s third attack wave, there was a brief respite in the 

aerial battle. At 1300 Mitscher ordered a search for the enemy carriers between 

185° and 315° and out to 350 miles. Except for contact with enemy aircraft, the 

results were negative.237

Ozawa suffered another major setback with the sinking of yet another large carrier. At 1120 Cavalla fired a spread of six torpedoes at the 25,675-ton Shōkaku. 

The carrier received three hits and was badly damaged. At 1215, Cavalla reported 

having scored three torpedo hits on Shōkaku, which had been accompanied by two 

heavy cruisers and three destroyers, at 11° 50ʹ north, 137° 52ʹ east. Subsequently 

Cavalla was heavily depth-charged.238 At 1501 Shōkaku sank, about 410 miles from 

Guam, at 12° north, 137° 46ʹ east.239

Between 1100 and 1130, Ozawa launched the fourth and the last attack wave of 

the day, comprising eighty-two planes (thirty Zeros, nine Judys, twenty-seven Vals, 

ten Zero fighter-bombers, and six Jills) from four carriers (Junyō, Hiyō, Ryuho, and 

Zuikaku).240 The pilots were ordered to attack “objective 15 Ri” but failed to find it 

because of the incorrect position given by the search planes. The largest group in 

this attack was from CarDiv 2, with forty-nine planes (twenty Zeros, twenty-seven 

Vals, and two Jills); it was directed to land on Guam. At about 1450, as the aircraft 

approached the island and prepared to jettison their bombs, they were picked up 

by the radars of TF 58. They were intercepted by the last CAP of the day, twelve 

Hellcats from the light carrier Cowpens (CVL 25, in TG 58.4). They were joined 

by seven Hellcats from the fleet carrier Essex (CV 9, in TG 58.4) and eight more 

Hellcats from Hornet (TG 58.1). Thirty out of forty-nine Japanese aircraft were shot 

down as they tried to land. The remaining nineteen managed to land at Orote but 

were damaged beyond repair.241

At about 1335, Ozawa received a report from the First Air Fleet on the sighting of five enemy carrier groups totaling ten regular carriers, thirteen converted 

carriers, nine battleships, and nineteen cruisers. The first group, bearing 322° and 

150 miles from the Marianas, was composed of three regular carriers, two special 

[converted] carriers, and one battleship; a second group, bearing 282° and distant ninety-five miles, comprised four regular carriers and four battleships; a third 

group, at bearing 226° and eighty miles, consisted of three regular carriers, four 

battleships, and nine cruisers. The fourth group, bearing 320° and forty-seven 

miles away, consisted of eight carriers (probably converted carriers) and ten heavy 

cruisers. Finally, the fifth group, bearing 300° and a hundred miles away, comprised 

three converted carriers.242
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The air battle continued at varying intensity until 1500. By then, TF 58’s carriers were steaming eastward and approaching the lee (downwind) side of Guam.243

Mitscher remarked that he was in the unfortunate position of fighting a defensive 

battle close to the lee side of the enemy land bases to which carrier planes could be 

shuttled, and at the same time on the windward side of enemy carriers.244

Most of the Japanese air attacks were intercepted by U.S. fighters fifty to sixty 

miles from the center of TF 58. The Japanese attacked repeatedly from the westward in groups, some of only a few aircraft, others up to seventy. Their attacks were 

poorly coordinated. Mitscher enjoyed a great advantage of having all 467 of his 

aircraft available for defense alone. Only about forty enemy aircraft penetrated the 

fighter defenses in the course of the day.245

Because enemy carrier aircraft were trying to land on the airfields of Guam and 

Rota, Mitscher gave orders to his bombers and torpedo aircraft in the air to bomb 

these fields. Spruance directed TG 58.4 to coordinate its actions with the escort carriers of TF 51.246 The U.S. fighters, dive-bombers, and torpedo bombers repeatedly 

attacked Guam during the day. The airfields at Orote and Agana on Guam were 

cratered, and damage was inflicted on the airstrip on Rota.247

In the meantime, the carrier Taihō suffered a large internal explosion at 1432 

and sank at about 1532.248 The ship went down with 1,650 officers and men out of 

its complement of 2,150. Ozawa shifted his flag to the heavy cruiser Haguro at 1606. 

The next day at 1200 he transferred to the carrier Zuikaku.

249

Ozawa learned that the first attack wave from CarDiv 2 had failed to find its 

assigned target only after transferring to Haguro. Moreover, the launch of the second attack wave from CarDiv 3 was canceled because of the need to accommodate 

aircraft from other carriers.250 If the aircraft from CarDiv 1 had to be used again 

they would have to land at night, because the aircraft that took part in the second 

attack wave would start to recover at about 1500. Preparations were also made to attack “objective 15 Ri,” but because of the loss of Taihō these preparations were canceled. Most of the aircraft of the second attack wave from Taihō were transferred to 

Zuikaku.

251

After his transfer to Haguro, Ozawa assessed the actions of his forces during the 

day. He concluded that the Japanese air attacks had fallen short of his expectations. 

Hence, he decided to carry out another attack.252 However, he had only about 102 

planes left out of the 430 he had brought from Guimaras.253 He could attack the 

enemy only after reorganizing the First Mobile Force and obtaining support from 

land-based aircraft.254 Moreover, unbeknownst to Ozawa at that time, the reports he 

had received from his fliers and from Admiral Kakuta on enemy carriers sunk were 

erroneous. He also received a false report from Kakuta that a substantial number 

of carrier planes were now safe on Guam. Accordingly, Ozawa believed that Kakuta 

still had more than five hundred planes available to attack the enemy carriers.255 In 
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fact, however, American aircraft had already destroyed the majority of these planes 

in repeated attacks on Saipan, Guam, Tinian, and Rota. Ozawa never understood 

this, misled by deliberately false claims of success from Kakuta.256

Ozawa’s force began to refuel on the afternoon on 19 June. However, receiving 

a report that his forces had been sighted by enemy carrier aircraft, Ozawa immediately stopped refueling, increased speed to twenty-four knots, and headed northwest.257 At 1800, he ordered his forces to concentrate and reach a designated position at 0700 on 20 June. Force A would sail on a course 90° at sixteen knots. Two 

hours later he also issued an order to the 1st and 2nd Supply Forces to proceed to 

the assigned point for refueling.258 The last Japanese attack of the day took place at 

1823 and carried on to Guam. U.S. aircraft followed them and shot them down as 

they were landing.259

In the meantime, at 1545, TF 58’s afternoon carrier search reported the Japanese 

fleet at 15° 00ʹ north, 135° 25ʹ east, on course 270° and speed twenty knots. Additional reports received within the next hour indicated that it was composed of battleships, carriers, cruisers, oilers, and destroyers. It was divided into three groups: 

a northern group (one carrier, four BBs, six CAs, several DDs), a southern group 

(two light carriers, two oilers, several DDs), and a western group (many ships, 

types uncertain).260 At least one group was on a northerly course at ten knots.261 The 

northern group was about ten miles north of the southern group, and the third, 

larger group was some twenty-five miles westward.262

By midafternoon Spruance no longer feared an enemy end run.263 At 1630 he 

sent Mitscher a message: “Desire to attack enemy tomorrow if we know his position 

with sufficient accuracy. If our patrol planes give us required information tonight 

no carrier searches should be necessary. If not, we must continue searches tomorrow to ensure adequate protection for Saipan. Point OPTION should be advanced 

to westward as much as air operations permit. Damaged ships tomorrow proceed 

Saipan anchorage.”264

At 1634, Spruance received a delayed report from an SWPA B-24 Liberator 

search plane of two enemy carriers, two heavy cruisers, and many destroyers at 

12° north, 137° 30ʹ east on course 170° and at twenty-five knots. The sighting had 

occurred at 1120.265

At dusk, Spruance sent a report to Nimitz about the events of 19 June: 

Task Force 58 made 325-mile search from 185 degrees, launching at 0530 in latitude 14° 35ʹ north, longitude 143° 40ʹ east. Air attack on Task Force 58 commenced at 1045 coming 

initially from westward and continued for several hours. Some enemy planes landed on 

Guam and Rota but these fields were hit by Task Force 58 planes several times to prevent 

their use. Over three hundred enemy planes are reported destroyed by our planes and AA 

fires. Own aircraft losses not yet reported. Only known damage to our ships: 1 hit on South 

Dakota which does not affect her fighting efficiency. Believe enemy has made long strikes 

depending on Rota and Guam fields for reservicing. If so, his plane losses may be greater 

than expected.266
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This message caused mixed feelings on the part of Nimitz’s staff. TF 58 had suffered little damage, but more importantly, Spruance had failed to inflict any damage 

on the enemy carriers. Spruance’s position at the time of the first search on 19 June 

had been only about ninety miles northwest of Guam and Rota and 125 miles southwest of Saipan. It was obvious to Nimitz’s staffers that Spruance had kept TF 58’s carriers too close to the beachhead. Reportedly, Admiral Towers demanded that Nimitz 

fire Spruance for mishandling the carriers and recommended himself as a replacement.267 Nimitz wisely refused to criticize Spruance’s action without full knowledge 

of the situation. Spruance’s mission was to “capture, occupy and defend Saipan, 

Tinian and Guam.” There had been no mention about going on the offensive against 

an enemy fleet. In Nimitz’s view, staying close to the Marianas and making the enemy airfields on Guam and Rota unusable may have been the safest way to prevent 

shuttle bombing or attacks by aircraft coming down from Japan via the Bonins.268

At 1930, Spruance detached TG 58.4 to proceed to a refueling position. This 

carrier group had been striking Guam and Rota.269 At 1957, Lockwood informed 

Spruance that a series of DF fixes had located major units of the enemy fleet within 

a hundred miles of 10° 30ʹ north, 136° 30ʹ east at 1800. The last U.S. plane was recovered at 1945. Afterward, TF 58 changed its course to 270° and increased speed 

to eighteen knots. The intention was to reach a position by daylight on 20 June 

to attack the enemy fleet or to attack a reportedly damaged Shōkaku-class carrier 

(in fact, Shōkaku itself);270 Spruance had received a reliable report that a U.S. submarine had torpedoed a carrier about 375 miles west of TF 58. He believed that 

enemy forces were in full retreat. Spruance estimated that the Japanese had lost 383 

aircraft, TF 58 only twenty-five. Aircraft had inflicted no damage on carriers; one 

battleship had been slightly damaged.271

At 2245, Ozawa directed his force to sail immediately to the northwest and maneuver as necessary to refuel on 21 June. Toyoda had directed Ozawa to fight a 

“running” battle after reorganizing the First Mobile Force and to refuel on the 21st. 

Damaged ships would proceed to their bases in Japan. Some of the aircraft carriers would proceed for training in the Lingga Archipelago. Ozawa was to attack the 

enemy task forces in cooperation with land-based aircraft on 22 June. Afterward, 

he would deploy his air units to land bases, where they would come under control 

of the Commander, 5th Base Air Force. The aircraft carriers would proceed to their 

respective training bases. After 22 June, Ozawa was to use the remaining forces 

under his command for “mopping up” operations around Saipan.272 For his part, 

Mitscher, in his initial report for the actions on 19 June, claimed that 358 enemy 

aircraft had been shot down, while his own losses were only twenty-five aircraft.273

The Japanese official report admitted losses of 450 aircraft but estimated that 160 

enemy aircraft had been shot down. 
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The real figures are different. The actual American losses on 19 June were 

twenty-six aircraft, and twenty-four pilots and crews.274 Some three hundred U.S. 

carrier aircraft (all but five of them Hellcats) had engaged enemy aircraft. About 

thirteen had been shot down, and six had been lost to operational causes. The personnel losses, after rescue operations, were ten pilots and seven air crewmen killed. 

In addition, four officers and twenty-seven enlisted men had been killed on three 

ships damaged or suffering near misses.275 The Japanese had employed 373 carrier 

aircraft for searches and strikes; only 130 returned. They also lost fifty Guam-based 

aircraft.276 U.S. submarines sank two large carriers, Taihō and Shōkaku. Many other 

planes had been lost ditching into the sea, crashing on carrier decks, or going down 

with the two sunken carriers. The total Japanese losses for 19 June had been about 

315 aircraft.277

The main reason for the Japanese losses was lack of coordination between various carrier groups and between carrier and land-based aircraft.278 Ozawa went into 

battle with half the aircraft the enemy had. His pilots were inexperienced. Ozawa 

was misled on the third and fourth attacks about the location of TF 58. He was also 

led to believe that Guam was a sanctuary when in fact it was a graveyard. Ozawa fully 

expected to have five hundred aircraft available from land bases but he never did.279

JICPOA assessed on 19 June that the enemy aircraft destroyed by TF 58 represented some 70 percent of the enemy’s nine air groups. The remaining aircraft 

would be adequate for two air groups for carriers of the Shōkaku class. The Japanese 

would require at least three months to reconstitute nine air groups—much longer, 

in fact, to form air groups with training equivalent to that with which CarDiv 1 had 

begun the battle (six months), or CarDiv 2 (three and a half months), or CarDiv 

3 (four and a half months). This delay would be caused more by a lack of trained 

aviators than a shortage of planes. JICPOA pointed out that this assessment was 

based on information that had proved excellent in the past and was considered 

reliable.280

At midnight on 19–20 June, TF 58 (minus TG 58.4) was west of Saipan on course 

260° at twenty-three knots.281 The Fifth Fleet’s night searches were extended out to 

550 miles between the bearings of 260° and 270°, and to seven hundred miles between bearings 270° and 300°. However, none of the searches detected the enemy 

fleet. At 0530 on the 20th, TF 58, by then at 13° 33ʹ north, 141° 03ʹ east, launched 

searches covering the bearings from 205° to 325°. The presence of enemy heavy 

cruisers was assumed, because of contact with Jake seaplanes. Spruance had had 

no report on any Japanese force since 1215 the previous day, when he had received 

Cavalla’s report of having torpedoed Shōkaku. He advised Mitscher that Zuikaku

(which had been damaged by a bomb that day) might still be afloat and if so would 

most likely head northward. He stated, “Desire to push out searches today as far 
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westward as possible. If no contacts with the enemy fleet consider it indication fleet 

is withdrawing and farther pursuit after today will be unprofitable. If you concur, 

retire tonight toward Saipan. Will order our tankers with TG 58.4 and direct TG 

58.4 remain in vicinity of Saipan. The carrier Zuikaku must be sunk if we can reach 

her.”282

By midmorning, Spruance still had no information on the location of Ozawa’s

force. He directed Mitscher to continue searches, indicating that if no enemy 

ships were found, TF 58 would stop its pursuit.283 At noon Mitscher sent a special fighter search/strike group armed with five-hundred-pound bombs. The 

fighters flew 450 miles but failed to establish contact; they flew slightly too far 

north.284 At 1330, TF 58’s carriers launched afternoon searches from 13° 25ʹ

north, 139° 20ʹ east between 235° and 355° out to 325 miles.285

Finally, after so many fruitless searches, aircraft in two separate sectors in 

TF 58’s regular afternoon 250-mile search sighted Ozawa’s forces.286 At 1545, 

TF 58 was at 13° 53ʹ north, 139° 05ʹ east when a report was received from 

one of its search planes indicating an enemy force at 15° 00ʹ north, 135° 25ʹ

east, on course 270° and speed twenty knots. Within the next hour, Mitscher 

received a second report that the enemy force was disposed in three groups 

and included carriers, battleships, cruisers, destroyers, and oilers. No aircraft had been observed on the decks of the enemy carriers.287 Ozawa’s force 

was steaming in three groups. One was composed of one carrier (Zuikaku),

two CAs (Haguro and Myoko), and several destroyers. Some twenty miles 

southwest was a second group, two converted carriers (Junyō and Hiyō), one 

light carrier (Ryuho), one battleship (Nagato), and one heavy cruiser (Mogami), plus a destroyer screen. About ten miles due south was the third group, 

three light carriers (Chitose, Chiyoda, and Zuihō), four battleships (Musashi, 

Yamato, Kongō, and Haruna), seven CAs (Takao, Maya, Atago, Kumano, Suzuya, 

Tone, and Chikuma), and a destroyer screen. In addition, there were also six oilers, with a few destroyers.288

At the time of the initial contact, Ozawa’s force bore 289° 290 miles from TF 

58, at the extreme range of U.S. attack aircraft.289 Another major problem was 

that darkness was only a few hours away. Spruance had a difficult decision to 

make. If the aircraft were launched so late in the afternoon, the pilots would attack in dusk and land at night, with gas tanks nearly empty. They could inflict 

some damage, but a follow-up attack the next morning would be nearly impossible, because of the confusion and delay in nighttime recovery of the planes. 

Nonetheless, Mitscher urged Spruance to attack immediately, and Spruance 

agreed.290

At 1520 Ozawa ordered both the 1st and 2nd Supply Forces to head immediately westward. At 1610 his search planes detected enemy carrier aircraft two 
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hundred nautical miles east of Zuikaku. Five minutes later, these planes sighted 

two carriers and battleships, plus other units, heading west. Ozawa decided to 

strike with torpedo bombers at dusk; the planes would land in the Marianas.291

At almost the same moment, 1620, Spruance decided to attack Ozawa’s force. 

Mitscher immediately turned his force eastward, into the wind. At 1638 the first of 

216 aircraft (eighty-five fighters, seventy-seven dive-bombers, and fifty-four torpedo bombers) from TF 58’s six heavy and five light carriers were launched.292 All 

were airborne within nine minutes. In the process, the U.S. carriers had moved 

away from the enemy, increasing the distance to about 340 miles by the time of the 

first attack by American aircraft.293

At 1700 Ozawa ordered a battle disposition for night combat. Twenty minutes 

later, he launched ten torpedo bombers, having decided to attack during the night. 

This decision was based on several factors, among them Ozawa’s expectations that 

the torpedo bombers would be successful and that land-based search planes would 

provide support the next morning. Also, no other enemy forces had been sighted 

in the vicinity of those detected earlier.294

Ozawa could launch only eighty aircraft before 216 aircraft from TF 58 attacked 

his force between 1840 and 1900. The Japanese observed about 130 to 150 enemy 

aircraft attack CarDiv 1, CarDiv 2, and the 2nd Diversionary Attack Force at 1840 

and for the next hour. They later estimated that CarDiv 1 was attacked by fifty 

aircraft, CarDiv 2 by forty, and the Diversionary Attack Force by about thirty-five. 

The Japanese would claim that more than forty were shot down during the air battle and seventy by AA fire.295

Mitscher’s report would state that his aircraft had sunk one large carrier of the 

Hitaka class (Hiyō) and had badly damaged, and probably sunk, another ship of 

that class (Junyō). He further reported that the carrier Shōkaku had received three 

or four thousand-pound-bomb hits, and one Kongō-class battleship and one heavy 

cruiser had been hit. Finally, he reported, one destroyer was believed sunk and two 

others damaged, and three tankers sunk and two others burning. Also, fifteen to 

twenty enemy aircraft had been shot down.296

At 1912, Spruance had rejected a suggestion from Mitscher to release Lee’s TG 

58.7 immediately to catch the enemy fleet. It was a mathematical impossibility that 

even these fast ships could overtake Ozawa. Even if some had been able to steam 

at a sustained speed of thirty knots (which was doubtful), they would have closed 

only 120 miles in twelve hours, slightly more than a third of the distance between 

Mitscher’s and Ozawa’s forces. In any case, at Mitscher’s recommendation TF 58 

had remained at sixteen knots to rescue as many pilots as possible. This meant that 

TF 58 was about four knots slower than Ozawa’s force.297

At 1945, Toyoda directed Ozawa to break away from the enemy at an opportune moment. Five minutes later, Ozawa received a message from Admiral Kusaka, 
J

Combined Fleet chief of staff, that the intention was to attempt a renewed attack. At 

2015 Ozawa directed the 1st and 2nd Supply Forces to steam immediately toward 

the west and then head for Nakagusuku Wan, a bay on the east coast of Okinawa.298

For Spruance and Mitscher, meanwhile, the most difficult task was to ensure 

that as many pilots as possible safely reached their carriers. However, because the 

attack had been carried out at extreme range, many inevitably would have to ditch. 

At 2042, TF 58 was at 14° 57ʹ north, 138° 28ʹ east. All task groups turned eastward 

and started recovery of aircraft. All destroyers were directed to recover pilots from 

the water.299

At 2045, the first aircraft returned. The entire force had to sail about an hour 

and a half on an easterly course to complete their recovery.300 Despite the threat 

of submarines, Mitscher ordered the carriers to illuminate their decks by shining 

searchlights directly up. Picket destroyers fired star shells to help pilots find their 

carriers.301 All red truck lights were turned on.302

In the aftermath of the attack there was great confusion among TF 58’s carrier 

groups. Many pilots of TGs 58.1 and 58.3 landed on board carriers of TG 58.2.303

Many aircraft ran out of gas and made forced landings in the water. TF 58 lost in all 

about ninety-five aircraft. Some had been shot down, but the majority were lost by 

crashing on flight decks or ditching into the sea.304

Because of the difficulty of recovering the pilots, it was not possible to continue 

pursuit of Ozawa’s force. Also, as Mitscher reported, many destroyers were low on 

fuel and needed to be refueled the next day. Hence, Spruance sent a message to 

Nimitz at 2217: “Enemy main body in four groups. 2045 position is latitude 15°

30ʹ N, longitude 133° 05ʹ E. Approximate course west. After completion recovery 

intend to come to course 315°, speed 16. Many carriers and enemy vessels damaged 

and in confusion. Intend to steam at 16 knots in order to recover many downed 

pilots as possible.”305

In the meantime, at 2046, Ozawa received the order from Toyoda to retire with 

his six remaining carriers, five battleships, thirteen cruisers, and twenty-eight destroyers.306 At 2100 he canceled his previous order for a night engagement, giving 

as the reasons that his torpedo bombers had been unable to detect the enemy force. 

In addition the enemy air attack on his main body and supply groups at 1530 had 

resulted in the loss of most of his carrier aircraft. He issued a new order that “in the 

event that there is little opportunity for a battle at night immediately retreat to the 

northwest.”307

Americans claimed that on 20 June at least forty enemy planes had been shot 

down in the air and approximately seventy planes destroyed by AA fire.308 At the 

end of the day the Japanese had only twenty-five aircraft left on their carriers.309

TF 58’s aircraft had not been as successful in attacking carriers and heavy surface ships as might have been expected. They had sunk only a single carrier—the 
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twenty-eight-thousand-ton Hitaka—and inflicted damage on four other carriers. 

The carrier Hayataka (Junyō) had suffered two direct hits and six near misses, 

while Zuikaku and Chiyoda had received one bomb hit each.310 The carrier Ryuho 

had suffered minor damage. The battleship Haruna had been damaged by a direct 

bomb hit. Also damaged was heavy cruiser Maya, while one destroyer (Hayanami)

had suffered minor damage. Two oilers (Genyo Maru and Seiyo Maru) had suffered 

heavy damage and had been abandoned; another oiler had been heavily damaged.311

The Japanese later greatly exaggerated their successes on 20 June, claiming to have 

shot down more than forty planes in the air battle and destroyed seventy by AA.312

The Pursuit, 21–22 June

After the major aerial battles on 19–20 June, Spruance decided to pursue Ozawa’s 

retreating force. The only hope of closing the distance, however, was lost when 

Spruance rejected Mitscher’s suggestion to release Lee’s TG 58.7.313 TF 58’s carrier 

groups were unable to close the range, because they had to turn away to launch and recover their aircraft. Another problem was that TF 58’s air searches were not successful.

During the night of 20–21 June, long-range PBMs based on Saipan searched 

westward out to seven hundred miles. At 2305, one made contact with Ozawa’s 

force at 16° 15ʹ north, 133° 35ʹ east, reporting its course as 330°, its speed as fifteen. 

Spruance considered the prospects of overhauling the enemy fleet discouraging. 

However, he believed that there was a possibility of finding damaged enemy ships, 

so he decided to continue the pursuit. To that end, Spruance directed TG 58.4 and 

a fleet-oiler group to steam westward at best speed and latitude 15° 30ʹ north.314

Spruance did not know at that time that the carriers Hiyō and Shōkaku were still 

afloat. Nor did anyone on his staff know that a single torpedo hit had sunk Taihō.

315

At midnight on 20–21 June, TF 58 was on course 280° at a speed of sixteen knots, 

four knots less than Ozawa’s force was making.316 At 0100, Mitscher canceled a 

previous order for night strikes, because the enemy was probably not within range. 

About half an hour later, another PBM from Saipan reported twenty-five enemy 

ships at 16° 30ʹ north, 132° 48ʹ east, on course 330°, speed fifteen, and trailing oil.317

The distance between the opposing fleets was then about 327 miles; Ozawa’s force 

bore west by north (285°) from Spruance’s.318

At 0200, only a few hours after completing recovery, TF 58 started a new search 

for the enemy. Several long-range night-flying Avengers were launched from Enterprise and Bunker Hill between then and 0300.319 When dawn came, however, TF 

58 was in disarray. Its ships were scattered over the ocean. Its carriers were sorting 

out their aircraft, many having landed the night before on the first available flight 

deck. Spruance and Mitscher reorganized the force and continued their pursuit 

and search westward but could find only cripples.320 TF 58 was still steaming at low 

speed to facilitate rescue of pilots, and it became evident that it had no chance to 

overtake Ozawa’s force.321
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At 0600, nevertheless, each task group of TF 58 launched a deck-load strike of 

Hellcats carrying 450-pound bombs in the hope of sinking the cripples. The pilots 

were directed to return if they found no targets after flying about three hundred 

miles. None of them found any enemy ship.322 However, at 0743 an Avenger from 

Bunker Hill sighted the enemy force at 17° 30ʹ north, 131° 40ʹ east, on course 300°

at twenty knots.323 That was about 360 miles away, well beyond the effective range of 

the U.S. carrier bombers.324 Mitscher reported to Spruance that his scouting planes, 

fitted with a special fuel tank, could search out to 360 miles but that strikes were 

limited to 250.325 The new information on the location of the enemy confirmed 

Spruance’s belief that Ozawa was trying to reach his home bases and was moving 

faster than TF 58. Hence, there was no chance to close the range and attack. For this 

reason Spruance directed Mitscher to carry on the search for cripples and to seize 

every opportunity to strike.326 Spruance also ordered Mitscher to detach TG 58.2 

(less carriers Cabot and Monterey) to join TG 58.7 as the battle-line carrier group, 

which was to attack the enemy force and “inflict maximum damage.”327

In the meantime, Ozawa directed CarDiv 3 to search between 90° and 180° and 

out to 350 nautical miles. These searches were negative. At 0715, Force A and Force 

B were directed to proceed to Nakagusuku Wan and the 2nd Diversionary Attack 

Force to Guimaras.328 At 1030, Ozawa concluded that his force had successfully 

evaded pursuit by the enemy fleet. All units of the main force were directed to reach 

Nakagusuku Wan by the morning of the 22nd. The 2nd Diversionary Attack Force 

would be in a state of readiness in the central and southern parts of the Philippines. 

The battleship Fusō and 1st and 2nd Supply Forces were assigned to the 2nd Diversionary Attack Force. However, because of the enemy action and the difficulties 

of refueling at sea, Ozawa decided that the 2nd Diversionary Attack Force would 

temporarily anchor at Nakagusuku Wan, refuel, and then set out for Guimaras.329

The Second Fleet was sent to the Singapore area, and the 3rd Fleet was ordered to 

train and equip in home waters and to achieve readiness for future operations.330

Spruance’s pursuit of Ozawa’s force had been complicated, as noted, not only by 

the need to sail on easterly courses to launch aircraft but also by low fuel states on 

board the destroyers. All task groups had to slow down. For example, Lee’s TG 58.7 

steamed at only eleven knots, on course 280°, from 1200 to 1516. After refueling it 

increased its speed to fifteen knots.331 At 1050 on 21 June Spruance directed Admiral Lee, now reinforced by Wasp and Bunker Hill (which had been sent to him, as 

noted above, for air cover), to press ahead at best speed. At 1126 Spruance himself 

boarded Indianapolis to join the battle line. The carriers followed, making good 

about fifteen knots. However, some of the group’s destroyers were dangerously low 

on fuel and had to be refueled. This led to a further delay, while from 1205 until 

1454 battleships fueled destroyers, steaming between eleven and fourteen knots. 
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At 1516, TF 58 increased to fifteen knots, and on 280°.

332 During the first twelve 

hours on 21 June, TF 58 made good only 150 miles. It was actually falling behind 

the enemy.333

At about 1500, TF 58 launched another search group. Spruance allowed it four 

hours to make contact.334 At 1920, shortly after the sun went down, when no enemy 

ships had been sighted, Spruance directed Mitscher to retire on course 90°, along 

parallel 15° 30ʹ north.335 At 2000, Spruance abandoned the pursuit. TF 58 was then 

at position 16° 02ʹ north, 133° 54ʹ east, or some seven hundred miles from Saipan. 

TF 58 then turned to an easterly course toward Saipan. The last contact with the 

enemy fleet had been at 0743, when it was moving northwestward and at twenty 

knots.336 The battle of the Philippine Sea was over.

When Spruance turned away, Ozawa’s force was about three hundred miles 

from Okinawa. The same evening, Ozawa dictated a message to Toyoda offering 

to resign. He expressed his deepest regret that he had lost this opportunity to lead 

the Japanese on the glorious path of victory. Toyoda, after consulting with the navy 

minister, refused to accept Ozawa’s resignation.337

During the entire day on 21 June, efforts to rescue TF 58’s pilots continued by 

destroyers, scouting aircraft of TF 58, and planes based on Saipan. Lockwood also 

redeployed his submarines to assist.338 Many pilots were rescued and brought to 

safety; total losses were twenty-two pilots and twenty-seven other airmen.339 Lockwood also directed submarines to cover the enemy withdrawal, whether to home 

waters or Luzon.340

During the night of 21–22 June, six PBMs from Saipan searched bearings from 

240° to 300° and out to seven hundred miles. However, results were negative.341

At about noon on 22 June, TF 58 made a prearranged rendezvous with fleet oilers 

some 220 miles east of the point where the retirement had commenced. Refueling 

continued until nightfall and was completed the next day.342

On 22 June, Ozawa’s main body and the majority of the 2nd Diversionary Attack 

Force entered Nakagusuku Wan at 1300 and 1500, respectively. The transfer of personnel from the sunken ships to other ships in the force then started.343 Four of the 

six surviving carriers, together with the battleship Haruna and the heavy cruiser 

Maya, had to proceed to Japan either for repairs or for long-delayed upkeep. The 

fleet brought back only thirty-five serviceable planes.344 Toyoda directed Ozawa 

that the entire force (less battleship Fusō and light cruiser Natori) was to proceed to 

the western part of the Inland Sea.345

In this decisive encounter between opposing carrier forces, out of nine Japanese 

carriers, six survived. However, their fighting strength was emasculated, because so 

many pilots were lost.346 The United States claimed that the Japanese lost 476 planes 

and 445 aviators.347 Between leaving Tawi-Tawi at 1000 on 13 June and launching 
J

the first air attack at 0730 on 19 June, the First Mobile Force transited some 1,550 

miles at average speed of thirteen knots after allowing twenty-four hours for refueling en route.348

The Japanese after-action report concluded that the battle should have been 

fought in the Iwo Jima area. Its authors blamed inadequate intelligence and air 

search for the ultimate failure of the A-Go operation. Further, the report’s drafters argued, Japanese search planes having detected the U.S. fleet, on 18 June at a 

distance of 380 miles, the enemy carriers should have been attacked that afternoon. 

Finally, they held, had the A-Go operation started on 12, not 15, June, the enemy 

carriers could have been attacked on the 15th, and a decisive battle could have been 

fought even earlier.349 However, the main reason for the Japanese failure was the 

incomplete state of training of the pilots and their lack of flying experience. 

NOTES 1 Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, p. 2, 

folder Fifth Fleet serial 0036, 13 July 1944, box 42, 

Third Fleet July 21, 1945 to Fifth Fleet, 13 July 1944, 

Record Group [RG] 38, Records of the Office of 

the Chief of Naval Operations, Records Relating to 

Naval Activity during World War II, WW II Action 

and Operational Reports, National Archives and 

Records Administration, Washington, D.C. [hereafter NARA].

2 Ministry of Defence (Navy), War with Japan, vol. 4, 

The South-East Asia Operations and Central Pacific 

Advance (London: Her Majesty’s Stationery Office, 

1995), p. 113.

3 The U.S. aircraft sank one torpedo boat, one 

auxiliary net layer, seven transports, one cargo 

ship, two army cargo ships, and one merchant 

vessel; one transport, one coastal defense vessel, two 

submarine chasers, one auxiliary submarine chaser, 

and an auxiliary minesweeper were damaged. A 

minelayer torpedoed by a U.S. submarine was 

further damaged at Apra Harbor. Robert J. Cressman, The Official Chronology of the U.S. Navy in 

World War II (Washington, D.C.: Contemporary 

History Branch, Naval Historical Center, 1999), 

p. 496. 

4 “Operations in Preparation for the Assault and 

Capture of Saipan,” p. 10, folder Task Force 58, 

11 September 1944, box 215, TF 58 9-11-44 

Vol. 1 to TF 58 9-11-44 Vol. 2, RG 38, Records 

of the Office of the Chief of Naval Operations, 

Records Relating to Naval Activity during World 

War II, WW II Action and Operational Reports, 

NARA.

5 Cressman, Official Chronology of the U.S. Navy in 

World War II, p. 496. 

6 Ibid., p. 497.

7 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, pp. 2–3.

8 Samuel Eliot Morison, History of United States Naval 

Operations in World War II, vol. 13, New Guinea and 

the Marianas, March 1944–August 1944 (Boston: 

Little, Brown, 1953), pp. 239–40.

9 The A-Go Operation, May–June 1944, Japanese 

Monograph No. 90 (Tokyo: Foreign Histories 

Division, General Headquarters Far East Command, 

1950), p. 45. 

10 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, p. 112.

11 ComFifthFleet War Diary for Month of June 1944, 

p. 2, folder June–December 1944, box 32, Commander Fifth Fleet April 1944 to April 1945, RG 38, 

Records of the Office of the Chief of Naval Operations, Records Relating to Naval Activity during 

World War II, World War II Diaries, NARA.

12 Ibid., p. 4.

13 Ibid., p. 5.

14 Ibid., p. 6.

15 Ibid., p. 7.

16 Ibid., pp. 8–9.

17 JICPOA–Commander in Chief Pacific Fleet 

[CINCPAC] Intelligence Bulletins, 10 May–30 

June 1944, p. 1, folder 3222/23, box 108, 

JICPOA-CINCPOA Bulletins 1 December 1942–30 

June 1944, RG 38, Records of the Office of the Chief 

of Naval Operations, Records of Naval Security 

Group Central Depository Crane Indiana, Inactive 

Stations, NARA.

18 Joint Intelligence Center Pacific Ocean Area 

[JICPOA], “Estimate of Enemy Distribution and 

Intentions, April 1943–July 1944,” p. 294, entry A1 

9024, container 3, SRMD 8–11, RG 457, National 

Security Agency / Central Security Service, 

Intelligence Reports from U.S. Joint Services and 

Other Government Agencies, December 1941–

October 1948, NARA.

19 Ibid., pp. 296–97.
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20 Thomas B. Buell, The Quiet Warrior: A Biography 

of Admiral Raymond A. Spruance (Annapolis, Md.: 

Naval Institute Press, 1987), p. 283.

21 E. P. Forrestel, Admiral Raymond A. Spruance: A 

Study in Command (Washington, D.C.: U.S. 

Government Printing Office, 1966), p. 132; Morison, 

New Guinea and the Marianas, p. 238.

22 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 2.

23 Forrestel, Admiral Raymond A. Spruance, p. 132; 

Morison, New Guinea and the Marianas, p. 238.

24 COMINCH Summaries of Radio Intelligence 

Japanese Naval Activities (1 April 1944–30 June 

1944), p. 1672, entries SRNS 0719–SRNS 0809 (pp. 

1487–1710), entry A1 9015, Summaries of Radio 

Intelligence Japanese Naval Attaché Messages 

(Japanese Naval Radio Intelligence Summaries, 

1942–1946), container 3, SRNS 719–1083, RG 457, 

National Security Agency / Central Security Service, 

NARA [hereafter COMINCH Summaries of Radio 

Intelligence, 1 April 1944–30 June 1944].

25 JICPOA-CINCPAC Intelligence Bulletins, 10 May–

30 June 1944, p. 1.

26 Ibid., pp. 2–3.

27 COMINCH Summaries of Radio Intelligence Japanese Naval Activities, 1 April 1944–30 June 1944, 

p. 1667.

28 Ibid., p. 1669.

29 Ibid., p. 1683.

30 JICPOA-CINCPAC Intelligence Bulletins, 10 May–

30 June 1944, p. 1.

31 “Possible Course of Action,” p. 6, Task Force 58, 11 

September 1944, box 215, TF 58 9-11-44 Vol. 1 to 

TF 58 9-11-44 Vol. 2, RG 38, Records of the Office 

of the Chief of Naval Operations, Records Relating 

to Naval Activity during World War II, WW II Action and Operational Reports, NARA.

32 Ibid., p. 7.

33 Ibid.

34 Ibid.

35 Ibid., pp. 7–8.

36 Ibid., p. 8.

37 Ibid., pp. 8–9.

38 Ibid., p. 9.

39 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 1.

40 Ibid., p. 2.

41 Ibid., p. 3.

42 Ibid., p. 4.

43 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1671.

44 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 2.

45 ComFifthFleet War Diary for Month of June 1944, 

p. 9.

46 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 2.

47 ComFifthFleet War Diary for Month of June 1944, 

p. 132.

48 Ibid., p. 10.

49 E. B. Potter, Nimitz (Annapolis, Md.: Naval Institute 

Press, 1976, 1987), p. 299.

50 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1674.

51 John Prados, Combined Fleet Decoded: The Secret 

History of American Intelligence and the Japanese 

Navy in World War II (New York: Random House, 

1995), p. 569.

52 A-Go Operation, p. 25.

53 The A-Go Operations Log: Supplement, May–June 

1944, Japanese Monograph No. 91 (Tokyo: Foreign 

Histories Division, General Headquarters Far East 

Command, 1950), p. 16.

54 Matome Ugaki, Fading Victory: The Diary of 

Matome Ugaki, trans. Masataka Chihaya, with 

Donald M. Goldstein and Katherine V. Dillon 

(Pittsburgh, Pa.: Univ. of Pittsburgh Press, 1991), pp. 

395–96.

55 A-Go Operations Log: Supplement, p. 16.

56 Ibid.

57 Ibid., p. 15.

58 A-Go Operation, p. 39; A-Go Operations Log: Supplement, p. 12.

59 A-Go Operation, p. 25. 

60 Ibid., p. 39.

61 A-Go Operations Log: Supplement, p. 17.

62 Morison, New Guinea and the Marianas, p. 231.

63 A-Go Operation, pp. 39–40.

64 Ugaki, Fading Victory, pp. 398–99.

65 A-Go Operations Log: Supplement, p. 17.

66 Ugaki, Fading Victory, p. 400.

67 A-Go Operations Log: Supplement, p. 17.

68 A-Go Operation, p. 40.

69 Ibid., p. 26.

70 Ibid., p. 34.

71 Morison, New Guinea and the Marianas, p. 231.

72 A-Go Operation, p. 45.

73 Morison, New Guinea and the Marianas, p. 232.

74 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, pp. 1–2.

75 “Operations in Preparation for the Assault and 

Capture of Saipan,” p. 11; Morison, New Guinea and 

the Marianas, p. 231; Forrestel, Admiral Raymond A. 

Spruance, p. 135.

76 A-Go Operation, p. 40.

77 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 3.

78 Forrestel, Admiral Raymond A. Spruance, p. 135.

79 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 1.

80 Ibid., p. 2.

81 Ibid., p. 3.
J

82 A-Go Operation, p. 25. The discussion that follows 

(through the next citation) is drawn from this 

source, pp. 41–45, 62.

83 Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, p. 3; 

ComFifthFleet War Diary for Month of June 1944, 

14 July 1944, p. 11.

84 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 3.

85 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 1.

86 Ibid.

87 ComFifthFleet War Diary for Month of June 1944, 

p. 11.

88 Buell, Quiet Warrior, p. 284.

89 ComFifthFleet War Diary for Month of June 1944, 

p. 11.

90 Ibid.; Forrestel, Admiral Raymond A. Spruance, p. 

135; Buell, Quiet Warrior, p. 284.

91 ComFifthFleet War Diary for Month of June 1944, 

p. 12.

92 Buell, Quiet Warrior, p. 285.

93 Trent Hone, “U.S. Navy Surface Battle Doctrine and 

Victory in the Pacific,” Naval War College Review 62, 

no. 1 (Winter 2009), p. 84.

94 Forrestel, Admiral Raymond A. Spruance, p. 135.

95 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 3.

96 “Operations in Preparation for the Assault and 

Capture of Saipan,” p. 11; “Narrative Report: 

Operations of Task Force Fifty-Eight 11 June 

through 21 June 1944: Special Operations D Minus 

Four and D Minus Three Days,” p. 11, folder Task 

Force 58, 11 September 1944, box 215, TF 58 9-11-

44 Vol. 1 to TF 58 9-11-44 Vol. 2, RG 38, Records 

of the Office of the Chief of Naval Operations, 

Records Relating to Naval Activity during World 

War II, WW II Action and Operational Reports, 

NARA.

97 ComFifthFleet War Diary for Month of June 1944, 

p. 12.

98 Morison, New Guinea and the Marianas, p. 239.

99 Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, p. 3; 

ComFifthFleet War Diary for Month of June 1944, 

p. 12.

100 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 4.

101 ComFifthFleet War Diary for Month of June 1944, 

pp. 11–12.

102 Ugaki, Fading Victory, p. 404.

103 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1679.

104 Ugaki, Fading Victory, pp. 402–403.

105 Ibid., p. 403.

106 A-Go Operations Log: Supplement, pp. 19–20.

107 COMINCH Summaries of Radio Intelligence, 1 

April 1944–30 June 1944, p. 1677.

108 William T. Y’Blood, Red Sun Setting: The Battle of 

the Philippine Sea (Annapolis, Md.: Naval Institute 

Press, 1982), p. 76.

109 Ibid., pp. 76–77.

110 Morison, New Guinea and the Marianas, p. 241; 

Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 5.

111 Forrestel, Admiral Raymond A. Spruance, pp. 

135–36.

112 ComFifthFleet War Diary for Month of June 1944, 

p. 14.

113 “Battle Experience: Supporting Operations for the 

Capture of the Marianas Islands (Saipan, Guam, 

Tinian)—June–August 1944 (Third Major Stepping 

Stone Westward),” Information Bulletin No. 20, 21 

December 1944, Headquarters of the Commander 

in Chief, Washington, D.C., pp. 74–76.

114 A-Go Operation, p. 45.

115 A-Go Operations Log: Supplement, p. 20.

116 A-Go Operation, pp. 45–46; Ugaki, Fading Victory, 

p. 405.

117 Y’Blood, Red Sun Setting, p. 77.

118 “Operations in Preparation for the Assault and 

Capture of Saipan,” p. 13.

119 Ibid.

120 “Narrative Report,” p. 14.

121 Ibid.

122 Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, p. 5; 

Morison, New Guinea and the Marianas, p. 243.

123 Buell, Quiet Warrior, p. 289.

124 Y’Blood, Red Sun Setting, p. 79.

125 “Narrative Report,” p. 12; “Operations in Preparation for the Assault and Capture of Saipan,” p. 12.

126 “Operations in Preparation for the Assault and 

Capture of Saipan,” p. 15.

127 Cited in Morison, New Guinea and the Marianas, 

p. 243; Commander, Fifth Fleet, Initial Report on 

the Operation to Capture the Marianas Islands, p. 5; 

“Narrative Report,” p. 15. 

128 ComFifthFleet War Diary for Month of June 1944, 

p. 15.

129 Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, pp. 5–6; 

ComFifthFleet War Diary for Month of June 1944, 

p. 16.

130 Buell, Quiet Warrior, pp. 289–90.

131 A-Go Operations Log: Supplement, p. 20.

132 Morison, New Guinea and the Marianas, p. 232.

133 Barrett Tillman, Clash of the Carriers: The True 

Story of the Marianas Turkey Shoot of World War II 

(New York: New American Library, 2005), p. 91.

134 Morison, New Guinea and the Marianas, p. 232.

135 A-Go Operations Log: Supplement, p. 20.

136 Ugaki, Fading Victory, p. 406.

137 On the time of sighting, Y’Blood, Red Sun Setting, 

p. 75.
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138 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 1.

139 Forrestel, Admiral Raymond A. Spruance, p. 136.

140 Y’Blood, Red Sun Setting, p. 75.

141 JICPOA-CINCPAC Intelligence Bulletins, 10 

May–30 June 1944, p. 2.

142 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 6.

143 Buell, Quiet Warrior, p. 289.

144 “Narrative Report,” p. 16.

145 Ibid.

146 Buell, Quiet Warrior, p. 291.

147 “Operations in Preparation for the Assault and 

Capture of Saipan,” p. 17; “Narrative Report,” p. 17; 

Morison, New Guinea and the Marianas, p. 244.

148 Cited in Hone, “U.S. Navy Surface Battle Doctrine 

and Victory in the Pacific,” p. 85.

149 Buell, Quiet Warrior, pp. 291–92.

150 ComFifthFleet War Diary for Month of June 1944, 

p. 17; Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, p. 6.

151 Paul S. Dull, A Battle History of the Imperial Japanese 

Navy (1941–1945) (Annapolis, Md.: Naval Institute 

Press, 1978), p. 305.

152 ComFifthFleet War Diary for Month of June 1944, 

p. 17; Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, p. 6.

153 Buell, Quiet Warrior, p. 291.

154 “Operations in Preparation for the Assault and 

Capture of Saipan,” p. 17; “Narrative Report,” p. 17.

155 Potter, Nimitz, pp. 299–300.

156 Ibid., p. 299.

157 Y’Blood, Red Sun Setting, p. 83; Morison, New 

Guinea and the Marianas, p. 278.

158 Potter, Nimitz, p. 299.

159 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, pp. 6–7.

160 ComFifthFleet War Diary for Month of June 1944, 

p. 17.

161 Morison, New Guinea and the Marianas, p. 244.

162 Buell, Quiet Warrior, pp. 291–92.

163 “Operations in Preparation for the Assault and 

Capture of Saipan,” p. 17; Commander, Fifth Fleet, 

Initial Report on the Operation to Capture the 

Marianas Islands, p. 6; “Narrative Report,” p. 17; 

Forrestel, Admiral Raymond A. Spruance, p. 137.

164 Buell, Quiet Warrior, p. 292.

165 ComFifthFleet War Diary for Month of June 1944, 

p. 18.

166 A-Go Operation, pp. 46–47.

167 Bernard D. Cole, “Struggle for the Marianas,” Joint 

Force Quarterly (Spring 1995), p. 91. 

168 A-Go Operation, p. 47.

169 Ibid., pp. 47–48.

170 Y’Blood, Red Sun Setting, pp. 84–85.

171 Ibid., p. 85.

172 Morison, New Guinea and the Marianas, pp. 246–47.

173 Ibid., p. 247.

174 Y’Blood, Red Sun Setting, p. 86.

175 Ibid., p. 87.

176 Morison, New Guinea and the Marianas, pp. 260–61.

177 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 7.

178 Buell, Quiet Warrior, pp. 292–93.

179 Ibid., p. 290.

180 Ibid., p. 291.

181 Ibid., p. 295.

182 ComFifthFleet War Diary for Month of June 1944, 

pp. 19–20.

183 Ibid.

184 Ibid., p. 21.

185 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 7.

186 ComFifthFleet War Diary for Month of June 1944, 

p. 20.

187 Buell, Quiet Warrior, p. 295; ComFifthFleet War 

Diary for Month of June 1944, pp. 19–20.

188 Forrestel, Admiral Raymond A. Spruance, p. 137.

189 Dull, Battle History of the Imperial Japanese Navy,

pp. 304–305.

190 Morison, New Guinea and the Marianas, pp. 232–33.

191 ComFifthFleet War Diary for Month of June 1944, 

p. 20.

192 Forrestel, Admiral Raymond A. Spruance, p. 138.

193 Ibid.

194 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 8.

195 Y’Blood, Red Sun Setting, p. 88.

196 Potter, Nimitz, p. 304.

197 Morison, New Guinea and the Marianas, pp. 263–64.

198 Ibid., p. 265; Y’Blood, Red Sun Setting, p. 88.

199 A-Go Operation, p. 48; Morison, New Guinea and 

the Marianas, p. 265.

200 Morison, New Guinea and the Marianas, p. 265.

201 A-Go Operation, p. 48; Morison, New Guinea and 

the Marianas, p. 271.

202 Morison, New Guinea and the Marianas, p. 271.

203 Y’Blood, Red Sun Setting, p. 97.

204 A-Go Operation, pp. 48–49. 

205 Morison, New Guinea and the Marianas, p. 265.

206 ComFifthFleet War Diary for Month of June 1944, 

p. 20; Forrestel, Admiral Raymond A. Spruance, pp. 

138–39.

207 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 8.

208 Morison, New Guinea and the Marianas, p. 258.

209 Ibid., p. 257.

210 ComFifthFleet War Diary for Month of June 1944, 

p. 21.

211 Morison, New Guinea and the Marianas, p. 258.
J

212 Ibid.

213 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 9.

214 A-Go Operation, pp. 49–50; Dull, Battle History of 

the Imperial Japanese Navy, pp. 307–308; Morison, 

New Guinea and the Marianas, pp. 265–66.

215 Cole, “Struggle for the Marianas,” p. 91. 

216 A-Go Operation, pp. 49–50.

217 Dull, Battle History of the Imperial Japanese Navy,

pp. 307–308; A-Go Operation, p. 52.

218 Morison, New Guinea and the Marianas, p. 265; 

Dull, Battle History of the Imperial Japanese Navy,

pp. 307–308.

219 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, p. 130.

220 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 9.

221 Morison, New Guinea and the Marianas, pp. 265–66.

222 Dull, Battle History of the Imperial Japanese Navy,

pp. 307–308.

223 Tillman, Clash of the Carriers, p. 129.

224 Forrestel, Admiral Raymond A. Spruance, p. 139.

225 Morison, New Guinea and the Marianas, p. 265.

226 Tillman, Clash of the Carriers, p. 151.

227 A-Go Operation, p. 51.

228 Morison, New Guinea and the Marianas, p. 269; 

A-Go Operation, p. 50.

229 Morison, New Guinea and the Marianas, p. 269.

230 “Results of Operations on 11 June, 19 June and 20 

June,” p. 13, folder Task Force 58, vol. 1 of 2, 11 September 1944, box 215, TF 58 9-11-44 Vol. 1 to TF 

58 9-11-44 Vol. 2, RG 38, Records of the Office of 

the Chief of Naval Operations, Records Relating to 

Naval Activity during World War II, WW II Action 

and Operational Reports, NARA.

231 Morison, New Guinea and the Marianas, pp. 270–71.

232 “Results of Operations on 11 June, 19 June and 20 

June,” p. 13; Ministry of Defence (Navy), South-East 

Asia Operations and Central Pacific Advance, pp. 

130–31; Commander, Fifth Fleet, Initial Report on 

the Operation to Capture the Marianas Islands, 

p. 10.

233 Morison, New Guinea and the Marianas, p. 274.

234 A-Go Operation, p. 50. 

235 Morison, New Guinea and the Marianas, p. 271; 

Dull, Battle History of the Imperial Japanese Navy,

p. 308.

236 Morison, New Guinea and the Marianas, p. 272.

237 Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, p. 10; 

Morison, New Guinea and the Marianas, p. 272.

238 ComFifthFleet War Diary for Month of June 1944, 

p. 23.

239 A-Go Operation, p. 52; Commander, Fifth Fleet, 

Initial Report on the Operation to Capture the 

Marianas Islands, p. 10.

240 Morison, New Guinea and the Marianas, p. 272.

241 Ibid., p. 273; A-Go Operation, p. 51.

242 Ugaki, Fading Victory, p. 410.

243 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, p. 130.

244 Morison, New Guinea and the Marianas, p. 261.

245 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, pp. 130–31.

246 Ibid., p. 130.

247 “Results of Operations on 11 June, 19 June and 20 

June,” p. 13.

248 A-Go Operation, p. 52.

249 Ibid.

250 Ibid., p. 51.

251 Ibid.

252 Ibid., p. 52.

253 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, pp. 131–32.

254 A-Go Operation, p. 52.

255 Dull, Battle History of the Imperial Japanese Navy,

p. 308.

256 Cole, “Struggle for the Marianas,” p. 91.

257 Dull, Battle History of the Imperial Japanese Navy,

p. 308.

258 A-Go Operation, pp. 52–53.

259 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, p. 130.

260 Commander, Fifth Fleet, Initial Report on the 

Operation to Capture the Marianas Islands, p. 11; 

ComFifthFleet War Diary for Month of June 1944, 

pp. 26–27.

261 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 11.

262 ComFifthFleet War Diary for Month of June 1944, 

p. 26.

263 Buell, Quiet Warrior, p. 298.

264 ComFifthFleet War Diary for Month of June 1944, 

p. 24.

265 Ibid., p. 22; Commander, Fifth Fleet, Initial Report 

on the Operation to Capture the Marianas Islands, 

p. 10.

266 Potter, Nimitz, p. 300.

267 Ibid.

268 Ibid., p. 302.

269 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 10.

270 ComFifthFleet War Diary for Month of June 1944, 

p. 23.

271 Buell, Quiet Warrior, p. 298.

272 A-Go Operation, pp. 52–53.

273 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 10.

274 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, p. 131.

275 Cited in Morison, New Guinea and the Marianas, 

p. 277.
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276 Cited in ibid.

277 Buell, Quiet Warrior, p. 303.

278 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, p. 131.

279 Dull, Battle History of the Imperial Japanese Navy,

p. 309.

280 JICPOA, “Estimate of Enemy Distribution and 

Intentions, April 1943–July 1944,” p. 301.

281 ComFifthFleet War Diary for Month of June 1944, 

p. 25.

282 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 11.

283 Buell, Quiet Warrior, p. 299.

284 “Results of Operations on 11 June, 19 June and 20 

June,” p. 14.

285 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 11.

286 “Results of Operations on 11 June, 19 June and 20 

June,” p. 14.

287 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 11.

288 Dull, Battle History of the Imperial Japanese Navy,

p. 309.

289 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 12.

290 Buell, Quiet Warrior, p. 299.

291 A-Go Operation, pp. 54–55.

292 Dull, Battle History of the Imperial Japanese Navy,

p. 309.

293 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 12.

294 A-Go Operation, p. 55.

295 Ibid., pp. 55–56.

296 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 12.

297 Morison, New Guinea and the Marianas, pp. 

306–307.

298 A-Go Operation, p. 56.

299 ComFifthFleet War Diary for Month of June 1944, 

p. 27.

300 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 12.

301 ComFifthFleet War Diary for Month of June 1944, 

p. 27.

302 “Results of Operations on 11 June, 19 June and 20 

June,” p. 15.

303 Ibid.

304 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 12.

305 ComFifthFleet War Diary for Month of June 1944, 

pp. 27–28.

306 Morison, New Guinea and the Marianas, p. 305.

307 A-Go Operation, p. 55.

308 Ibid., p. 60.

309 A-Go Operations Log: Supplement, p. 27.

310 Names in parentheses for Hitaka and Hayataka are 

the ships’ real names; both belonged to the Hiyō class.

311 A-Go Operation, pp. 60–61; Dull, Battle History of 

the Imperial Japanese Navy, p. 309.

312 A-Go Operation, p. 56.

313 Morison, New Guinea and the Marianas, p. 306.

314 ComFifthFleet War Diary for Month of June 1944, 

p. 28.

315 Morison, New Guinea and the Marianas, p. 307.

316 Ibid.

317 ComFifthFleet War Diary for Month of June 1944, 

p. 30.

318 Morison, New Guinea and the Marianas, p. 307.

319 Ibid.

320 Ibid., p. 299.

321 Potter, Nimitz, p. 302.

322 Morison, New Guinea and the Marianas, p. 307.

323 ComFifthFleet War Diary for Month of June 1944, 

p. 31.

324 Morison, New Guinea and the Marianas, pp. 307–

308.

325 ComFifthFleet War Diary for Month of June 1944, 

p. 31.

326 Morison, New Guinea and the Marianas, p. 308.

327 ComFifthFleet War Diary for Month of June 1944, 

p. 31.

328 A-Go Operation, p. 56.

329 Ibid., p. 58.

330 Ibid., p. 26.

331 ComFifthFleet War Diary for Month of June 1944, 

p. 31.

332 Morison, New Guinea and the Marianas, p. 308.

333 Ibid., pp. 306–307.

334 Ibid., p. 308.

335 ComFifthFleet War Diary for Month of June 1944, 

p. 308.

336 Ibid.

337 Morison, New Guinea and the Marianas, p. 309.

338 ComFifthFleet War Diary for Month of June 1944, 

p. 32.

339 Commander, Fifth Fleet, Initial Report on the Operation to Capture the Marianas Islands, p. 13.

340 ComFifthFleet War Diary for Month of June 1944, 

p. 32.

341 Ibid.

342 Morison, New Guinea and the Marianas, p. 309.

343 A-Go Operation, p. 58.

344 Morison, New Guinea and the Marianas, p. 309.

345 A-Go Operation, p. 58.

346 Buell, Quiet Warrior, p. 303.

347 Ibid.

348 Ministry of Defence (Navy), South-East Asia Operations and Central Pacific Advance, p. 131.

349 Ibid.

VI Japanese A-Go Operation (Battle of the 

Philippine Sea), 13–22 June 1944

Conclusions and Operational Lessons Learned

The Combined Fleet and the U.S. Fifth Fleet operated over an ocean area 

stretching from the southern Philippines in the west to the Marshalls in the 

east. Prior to the beginning of the A-Go operation, Japanese naval forces 

and aircraft had available to them a large number of bases and airfields in the Central Pacific and southern Philippines. The Fifth Fleet had only the advance bases in 

the newly captured Marshalls and Gilberts. Their main bases at Pearl Harbor were 

thousands of miles from the pending operating area off the southern Marianas. 

Initially, the Fifth Fleet had to transit some 1,580 miles from its advance bases in the Marshalls to the Marianas; the deployment distance for the First Mobile 

Force was more than 1,900 miles. Prior to their deployments, both fleets operated 

from exterior positions. This situation had changed once the Fifth Fleet arrived in 

the proximity of the southern Marianas. Then its Task Force 58 operated from an 

operationally central position with regard to the approaching First Mobile Force. 

Japanese naval land-based aircraft in the Marianas occupied tactically a central position throughout the entire operation, while those aircraft based in the Palaus and 

on Yap and Truk operated from an exterior position. The American advance bases 

in the Marshalls and the Gilberts represented exterior positions in the invasion of 

the Marianas. The geographic positions and distances between them always play critical roles in a war at sea. Their importance is especially critical in the initial deployment of naval forces and aviation. The military characteristics of a maritime theater 

must be properly evaluated; yet the importance of geography and distances should not 

be overemphasized. Ultimately what counts most for the success in war is the factor of 

force, its human element in particular.

The Allies established a sound command structure in the Pacific theater. Admiral Nimitz had full control over all naval, ground, and air forces in the Pacific Ocean 

Areas (POA). The only exception was the Twentieth Air Force, which was controlled 

by General Arnold. Nimitz’s staff was composed of representatives of all services. 

Nonetheless, Nimitz had too many responsibilities. He was not only a theaterstrategic commander (as CINCPOA) but also an area fleet commander (as 

CINCPac). This sometimes created problems, because he was subordinate at the 
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same time to both the Joint Chiefs of Staff (JCS) and Admiral King. Spruance, as 

commander of the Fifth Fleet, exercised full authority and responsibility over all 

subordinate forces. He was de facto an operational commander, because he had authority over all forces deployed in the Central Pacific. Admiral Lockwood had control only over the submarines of the Pacific Fleet; however, he did not control the 

deployment and employment of submarines in the SWPA’s Task Force 71, which 

operated in the southwestern Pacific, including Philippine waters. A sound theater 

command organization should be simple and flexible. The chain of command should 

be straightforward, with clear lines of responsibilities for all commanders. All forces 

operating within the boundaries of a given maritime theater should be controlled by 

a single commander; otherwise no effective planning, preparations, and execution 

of military actions can be accomplished. This is especially critical in high-intensity 

conventional warfare. A theater commander should not overly centralize command 

and control by collecting too many responsibilities but should establish intermediate 

levels of command. 

In contrast to the Allies, the Japanese had a highly fragmented command structure. They never established a theater-strategic level of command in the Pacific theater as the Allies did. They also lacked a truly joint command in the Central Pacific. 

Relations between the Imperial Japanese Navy and Army at the highest levels were 

generally bad; this was less of a problem at the middle and lower command levels. 

The striking power of the Combined Fleet was concentrated in the First Mobile 

Force (often called the “First Striking Force” in JICPOA/COMINCH intelligence 

assessments), created on 25 February 1944 from the (disbanded) First Fleet and the 

Second Fleet. The First Mobile Force included the First Mobile Fleet (all the carriers), all the battleships of the former First Fleet, and the heavy cruisers and destroyers of the Second Fleet. The First Mobile Force continued to be directly subordinate 

to the Combined Fleet. On 10 March the Combined Fleet also established a new 

intermediate and geographically based command, the Central Pacific Area Fleet. 

The new command, under Admiral Nagumo, was intended to strengthen defenses 

in the Japanese mandated islands. In theory, Nagumo commanded all Japanese naval and ground forces in the Central Pacific. However, that was not the case in 

practice; his army counterpart retained full administrative and tactical control of 

all army units in the Central Pacific. The consequence of this lack of unity of command was that no unified plan was ever prepared for the defense of the Marianas. 

In the modern era, success in combat at the operational-tactical level and higher 

requires the closest cooperation of forces among two or more services—what the United States calls “jointness.” No single combat arm or service can reach its full potential 

today unless it is employed in combination with other combat arms, branches, or 

services. Shortcomings of one service can be balanced by capabilities of others. A joint 

force commander has more options than a single-service component commander in 
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employing forces, because sea, land, air, and special-operations elements collectively 

offer a wider range of possibilities. At the same time, the enemy is put at a great disadvantage against a multidimensional threat for which he might not have an effective 

counter. Multiservice forces allow creative operational commanders to combine their 

diverse but complementary capabilities in asymmetrical as well as symmetrical ways 

and to generate an impact greater than the sum of those of the individual parts.

By the beginning of 1944, the Allied strength in the air was overwhelming. In 

the first six months of 1944, as preliminaries to the invasion of the Marshalls, the 

isolation of Truk, and the landings in the Marianas, TF 58 and the Army and Navy 

land-based aircraft in SWPA, SOPAC, and CENTPAC conducted massive strikes 

and raids against Japanese strongpoints, bases, and shipping. These strikes were 

complemented by attacks by submarines against military and commercial shipping. 

Cumulatively, air strikes and submarines attacks wore down considerably Japanese 

air strength in the Central Pacific. A large number of naval vessels, mostly transports, were sunk or damaged; regular reinforcement and supply of Japanese forces 

in the Central Pacific were thereby made much more difficult. The mobility of TF 

58 allowed rapid shifting of strikes from one part of the theater to another. Allied 

air strikes also forced the Japanese to redeploy their forces to areas less exposed. On 

a few occasions the Japanese high command was misled regarding whether carrier 

strikes were raids or preludes to imminent invasion. Modern warfare at sea is a 

combination of decisive operation and weakening of the enemy by numerous tactical 

actions and over time—that is, “attrition.” A proper balance must be found between 

these two methods of combat employment of forces. Properly applied, the tenets of 

operational art should prevent attrition from, by design or default, predominating.

By 30 May 1944 Nimitz, Spruance, and all task force commanders were well 

informed about all major movements of the enemy naval forces and land-based 

aircraft in the entire Pacific theater, and specifically in the Central Pacific, the NEI, 

the Philippines, and western New Guinea. They had fairly accurate and reliable 

information on major organizational changes in the IJN and the location of fleet 

commanders. They also had good intelligence on Japanese plans and intentions. 

Most of this information was obtained through the radio intercept and radio traffic 

analysis and direction finding. Some was acquired from search aircraft and submarines. The biggest single success came in early July when, through an accident, 

American-led Filipino guerrillas retrieved a copy of the Combined Fleet’s plan for 

the Z operation. Also, Allied intelligence was occasionally able to get information 

on Japanese assessments of the situation and perceptions of possible future Allied 

actions. Intelligence plays an important, often critical, role in the decisions of operational commanders. Sources of intelligence should be diverse, and different methods 

of collecting, processing, and analyzing information should be used whenever possible. 

One should be very cautious in relying on decrypted messages; if the enemy becomes 
J

aware that his messages are being read, he can use them to feed false information and 

achieve surprise.

Admiral Nimitz and his staff were the key architects of the campaign plan for 

the seizure of the archipelagoes of the Central Pacific (Operation GRANITE II). Final decisions on the sequencing of major operations in the POA and SWPA were 

made by the JCS, although Nimitz and MacArthur, respectively, were consulted. 

Nimitz’s plan for the invasion of the Marianas (FORAGER), OPLAN 3-44, was clear 

and succinct. The ultimate objective of seizing control of the southern Marianas 

was to establish advance bases for attacks on the enemy maritime traffic, for the 

strategic bombing campaign against the Japanese home islands, and for the isolation and neutralization of the Carolines. Surprisingly, however, Nimitz’s plan 

mentioned nothing about how the Combined Fleet might interfere. By early May 

1944 American naval intelligence had reliable and accurate information on the redeployment of enemy carriers, large surface combatants, and destroyers from the 

Lingga Archipelago and the home islands to Tawi-Tawi, Davao, and other bases in 

the southern Philippines. Nimitz, Spruance, and their subordinate commanders 

received copies of the captured plan for the Z operation. Yet for some reason Nimitz 

and his staff did not change their assumptions about possible enemy reactions, or, 

accordingly, OPLAN 3-44. 

Spruance’s OPLAN 10-44 of 12 May was based on several realistic assumptions, 

primarily that the southern Marianas were strongly defended. It also assumed that 

Japanese long-range aircraft based in the Carolines and on Iwo Jima and Chichi 

Jima would attack U.S. forces in the southern Marianas. It further postulated that 

the Allied aircraft based in the Marshalls and in the SWPA would prevent enemy 

aircraft in the Carolines from interfering. In contrast to Nimitz’s plan, Spruance’s 

OPLAN 10-44 assumed the “possibility” that enemy naval forces and carrier-based 

aircraft would try to prevent the capture of the southern Marianas or to interfere 

with the unloading of material and personnel should the United States accomplish its objectives there. That assumption was the basis for the missions issued to 

Admiral Mitscher. However, Spruance clearly believed that enemy surface forces 

would interfere with the U.S. amphibious force after, not prior to, the landings on 

Saipan, Tinian, and Guam. Characteristically, Spruance delegated to Mitscher authority to modify the basic plan on the basis of changes in the situation. Operation 

plans should be short and clear. They should contain only information unavailable 

to subordinate commanders but necessary for sound decisions. A higher commander 

should take care not to omit assumptions critical for planning by subordinates. An 

operational commander should not base planning assumptions on the expected success of his forces. Planning assumptions should be few in number. They should deal 

with uncertainties in the operational situation that could have major impacts on the 

development and execution of plans.
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The Combined Fleet’s planning for defense of the Mandates was very thorough and methodical. Its initial plans were drafted in mid-August 1943, during 

the struggle for the control of the Solomons. The draft envisaged the destruction of 

the U.S. Pacific Fleet in a “single blow” should the Allies advance into the Central 

Pacific and the Philippines. That operation was anticipated for mid-1944. Formally, 

the IJN shifted after March 1944 to the strategic defensive, as directed by IGHQ. 

The weight of main effort shifted to the southeast area. This meant that the majority of the IJN’s surface forces was redeployed to the Inner South Seas Area. Admiral 

Koga drafted the Z operation plan, which called for the employment of the entire 

Combined Fleet against the U.S. Pacific Fleet.

The Z plan was ambitious, encompassing the entire area within the Japanese 

defense perimeter in the spring of 1944. It was also based on a rather inflexible view 

of the situation. Various operational districts and interception zones were drawn 

well in advance and divided into a number of “operational” districts. Excessive reliance on scripted scenarios and actions/reactions was typical of Japanese naval 

operational planning. It showed great lack of creativity on the part of senior naval 

commanders and their planners. Similarly, the basic Z plan consisted of four subordinate plans, based on whether certain scenarios happened or not. Each envisaged 

an attack from the flank; this might have been one of the reasons for Spruance’s 

concern that the enemy carriers might attempt to attack in the rear of TF 58. The 

greatest problems for the Japanese were lack of adequate training of the carrier 

air groups and uncertainty of fuel supplies. Operational planners should not rely 

on scripted scenarios, because they lead to overly detailed and inflexible plans and 

orders. An operation plan drawn well in advance should be regularly updated and, 

in case of drastic changes in the strategic or operational situation, modified or even 

abandoned. It should pose multiple threats to the enemy. It should avoid past patterns of employment of forces. It should be novel and creative and should surprise the 

enemy. A sound operation plan should include deception; the success of the basic plan 

should not depend on successful deception.

Admiral Toyoda only slightly modified the plan for the Z operation, renaming it 

“A-Go.” Like the previous plan, the A-Go plan envisaged employment of the entire 

carrier force, four air flotillas of the base air forces, and submarines in a decisive 

battle. Yet Toyoda did not provide timelines in his modified plan. The employment of the Base Air Force was predicated on the destruction of about a third of 

the enemy carrier forces prior to the beginning of a decisive battle. This seems 

unrealistic, because such a weakening of the enemy’s principal strength could not 

have been achieved prior to a decisive clash between carrier forces. Operation plans 

should be neither too detailed nor too broad. The basic plan for a major operation 

or campaign should provide some tentative timing and sequencing of the objectives 
J

to be accomplished; otherwise operational sequencing/synchronization and logistical 

support/sustainment cannot be properly planned.

The U.S. Fifth Fleet was numerically and qualitatively greatly superior to the 

First Mobile Force and the base air forces that took part in the A-Go operation. 

TF 58’s single greatest superiority was in combat experience and skill of its pilots, 

the reason for that being the U.S. Navy had a much more effective way of training 

its pilots than the IJN did. The American ships also had much more advanced and 

reliable radars and radios. However, the range of U.S. carrier aircraft was considerably shorter than that of their Japanese counterparts. That gave a potentially great 

advantage to Ozawa, who would be able to detect the U.S. carriers before they could 

detect his own. Ozawa was able to count as well on the support of naval land-based 

aircraft based in the Marianas and Carolines for search and attack; however, their effectiveness steadily decreased in the months preceding the A-Go operation. Ozawa’s 

carrier aircraft were potentially able to refuel at land bases and then reattack; they 

were also able to use land bases as sanctuaries in case of some damage. The United 

States had a large number of aircraft in the Gilberts and Marshalls, but they had 

inadequate range to attack Ozawa’s force. Another great disadvantage for Spruance 

was that because of the prevailing easterly trade winds, TF 58 had to steam away 

from Ozawa’s force to launch or recover aircraft.

The Japanese had a potentially significant advantage in their better doctrine 

for, and proven skills in conducting, night surface actions. This was the result of 

their doctrinal development and training in the interwar years. In contrast, the 

U.S. Navy had paid little attention to that important aspect of surface warfare in 

the 1920s and 1930s. In 1942–43, during the long struggle for the Solomons, it 

gradually improved its capabilities in night fighting. However, they were still inadequate. In peacetime, one should develop a sound and comprehensive doctrine for the 

combat employment of naval forces and aircraft; no aspect of naval warfare should 

be neglected or, worse, ignored; otherwise, it will not be possible to train and prepare 

properly for combat with a strong opponent. Errors made in peacetime are difficult, if 

not impossible, to correct once hostilities at sea begin. Faulty tactical doctrine has an 

invariably negative effect on the employment of naval forces and aviation in a major 

naval/joint operation or campaign. 

By June 1944, the U.S. Navy had an overwhelming superiority over the IJN in 

the logistical support and sustainment of its forces, which were deployed many 

thousands of miles from the nearest bases. Its underway-replenishment capabilities 

were unmatched.

TF 58 used advance bases in the Marshalls for rest and preparation for the invasion of the southern Marianas. Its carrier pilots were battle-hardened veterans 

of almost continuous combat in the spring of 1944. In contrast, the First Mobile 

Force required much training prior to the activation of the A-Go operation. After 
J()

mid-May the opportunities for training pilots were much reduced, because the 

First Mobile Force moved from Lingga to Tawi-Tawi, where there were no airfields. 

At Tawi-Tawi, however, its commanders and staffs were involved in a number of 

table maneuvers and war games in which all details of the A-Go operation plans 

were rehearsed. There were also numerous staff meetings. These preparations were 

much more thorough than those for the Midway-Aleutians operation in 1942. 

Orders issued by IGHQ and NGS on 3 May 1944 were the first documents 

specifying the operating areas of the Combined Fleet and setting a deadline for 

completion of preparations for a decisive battle. The First Mobile Force would be 

assembled in the south-central part of the Philippines, while the First Air Fleet 

would be deployed in the Central Pacific area, the Philippines, and north of Australia. A location for decisive battle would be selected as close as possible to the forces’ 

deployment areas. Should the U.S. Pacific Fleet attack prior to the completion of 

Japanese preparations, the Combined Fleet would avoid a decisive battle. Instead, 

enemy forces would be attacked by the Base Air Force and local area-defense forces.

Toyoda, in his order issued the same day, laid down that a decisive battle would 

be fought with the entire strength of the First Mobile Force and a major part of 

the Base Air Force. Toyoda selected the Palaus and western Carolines as the site of 

the battle. The Japanese plan for the A-Go operation was elaborate and envisaged 

almost every possible scenario, yet it was based on several false assumptions. For 

example, the Japanese were overconfident in decisive victory over the skillful and 

much stronger enemy fleet. They also seemed to underestimate the enemy’s ability to discern the movements and probable intentions of the Japanese forces. Yet at 

the same time, the Japanese commanders had fairly accurate information on the 

strength of the U.S. Fifth Fleet. Most of the data were obtained by land-based search 

aircraft and direction finding. Also, despite perennially poor intelligence support, 

the Japanese high command was able to deduce enemy intentions properly, on the 

basis of analysis of the enemy’s past actions but also of reliance on plain common 

sense and logical thinking.

The Fifth Fleet executed pre-invasion strikes by TF 58’s carriers and preliminary bombardments by heavy surface ships against the defenses, naval vessels, merchant shipping, and airfields in the southern Marianas as envisaged in Admiral 

Spruance’s basic plan. The air strikes encountered little opposition in the air. In 

addition, long-range heavy bombers based in SWPA, SOPAC, and CENTPAC conducted what are now called “operational fires” designed to isolate the Marianas 

from other Japanese-controlled areas and to prevent the arrival of air reinforcements. In planning a major amphibious landing on a defended shore it is necessary to 

conduct naval surface fire support and close air support shortly before and during the 

landing and during the battle ashore. Optimally, the amphibious objective area should 

be isolated from the rest of the enemy-controlled area by means of operational fires. 
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They can be also used to deceive the enemy about the true objectives of the amphibious forces and the timing of their landing.

During the pre-invasion strikes Spruance and his subordinate task force commanders received numerous alerts from JICPOA on the locations and movements 

of Japanese naval forces and aircraft in the southern Philippines. However, the 

most valuable reports were from TF 17’s submarines in the area. Bowfin’s report 

of 12 June on the presence of the enemy forces in the Sulu Sea, however, was in 

Spruance’s view inconclusive. He decided therefore to proceed with the planned 

landing on Saipan but at the same time alerted his fleet about the possibility of an 

engagement on 17 June. More important was the report the next day from the submarine Redfin of a large number of ships, including carriers, in the Sibutu Passage. 

For some reason Spruance considered that report too as inconclusive and so continued with the planned operations for the next four days. JICPOA and COMINCH 

daily radio-intelligence summaries on 13 June concluded that a major operation by 

the First Mobile Force was under way. Spruance should have taken these reports as 

conclusive enough to prepare his fleet for a battle, delay the landing on Saipan, and 

cancel strikes by two task groups on Iwo Jima and Chichi Jima. 

Mitscher’s estimate of the situation on 13 June described fairly realistically the 

operational situation facing his task force. In contrast to the view then prevalent in 

the Fifth Fleet, Mitscher and his staff warned that the Japanese might actually risk 

their fleet in defense of the Marianas and that the Fifth Fleet should be fully prepared for such an eventuality. Mitscher and his staff accepted the possibility of an 

end run by the enemy if TF 58 steamed too far westward without proper searches 

on its southern flank. Yet they apparently minimized the threat to U.S. shipping 

off Saipan. However, there is no way of knowing how much damage would have 

been inflicted on amphibious shipping or whether the enemy would have been 

destroyed in the process.

On 14 June, or one day prior to the landing on Saipan, Nimitz and his staff 

received quite accurate information about the composition of Ozawa’s force. They 

were now convinced that the Japanese intended to execute a modified Z operation. 

Likewise, King and his staff in Washington were not surprised by the movements 

of the enemy forces in the southern Philippines. 

After U.S. carrier strikes on the southern Marianas began, Toyoda received details of the composition of the enemy forces and their activities. He became quickly 

convinced that an invasion of the Marianas was imminent. He issued an alert order 

for the Combined Fleet in the late afternoon on 13 June and temporarily abandoned the effort to counter a landing on Biak. Toyoda decided that a decisive battle 

would be conducted on 19 June. His plan was that the First Mobile Force and the 

Base Air Force would attack the enemy “regular” (i.e., fleet) carriers—that is, the 

enemy’s operational center of gravity—during daylight hours. The initial attacks 
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would be conducted by the base air forces. Yet perhaps a better plan would have 

been to conduct simultaneous strikes from several directions by both carrier and 

land-based naval aircraft. 

Ozawa’s force maintained strict radio silence upon leaving Guimaras on 15 June 

and until the evening of the 18th. During the approach phase, Ozawa was regularly 

informed by Toyoda about the situation and enemy activities around the Marianas. 

This information, though it lacked detail, was sufficiently accurate to allow Ozawa 

to make sound assessments and decisions. He correctly concluded that the enemy 

carriers would not move more than three hundred miles west of Saipan and so he 

was in no danger of a flanking attack. Ozawa also was correct that the enemy would 

attack the southern islands in the archipelago first. 

For his part, Spruance’s main source of information between 15 and 18 June were 

reports from submarines. The most critical were sent by Flying Fish and Seahorse

on 15 June. Although JICPOA provided a steady stream of reports, none of them 

pertained to the location and movements of Ozawa’s force. However, Spruance and 

his task force commanders received many decrypted Combined Fleet messages to 

subordinate major commanders. Among other things, Nimitz and Spruance knew 

that Toyoda considered the operation then under way to be “decisive” and that the 

Japanese assumed that the United States knew that the First Mobile Force intended 

to fight on 18 or 19 June. They also had good knowledge of current and planned 

activity by Japanese naval aircraft in the Marianas and Carolines and on Mindanao. 

Yet neither Nimitz nor Spruance suggested, in the light of the change in the situation, delaying the landing on Saipan until the approaching enemy force was defeated and full local sea control obtained. Operational commanders should conduct 

running estimates of the operational situation once operations are under way. They 

should make new decisions in case of drastic changes in the operational situation, appropriately altering or even abandoning the operational plan.

By 16 June, submarine reports and information received from Nimitz had convinced Spruance that the Japanese had decided to risk everything and seek a decisive battle. Hence, he made a correct decision to delay the landing on Guam. On 

Admiral Turner’s recommendation, however, he did not move all the transports 

eastward from Saipan. Spruance had to pay attention to the views of his most senior 

subordinate commander, but when he made this decision, he was unaware that 

the situation on Saipan was not as grave as Turner told him. Spruance should have 

consulted not only Turner but also Gen. Holland Smith, who was the senior commander on the ground.

Spruance’s battle plan, issued in the afternoon of 17 June to Mitscher and Admiral Lee (CTG 58.7) was short but contradictory. Among other things, Spruance 

clearly stated that the objective of the pending operation was the “complete destruction” (emphasis added) of the enemy fleet. Yet that would have required giving TF 
J

58 full freedom of action, even to move out of supporting distance of the U.S. troops 

on Saipan and the invasion forces in the southern Marianas. Also, Spruance’s plan 

did not mention the possibility that the enemy might attempt a flanking attack. 

This was clearly an omission, because all his major decisions during the operation 

were almost exclusively influenced by that concern. The operational plan should describe the missions issued to their subordinate tactical commanders succinctly and yet 

clearly. They should not use language that contradicts previous decisions or expressed 

intentions. The words matter.

The decision to re-create TG 58.7 in the late afternoon of 17 June was perhaps 

unnecessary, since neither Spruance nor Lee was ready, and for good reason, to 

fight a night surface action. The major disadvantage of pulling battleships and accompanying cruisers and destroyers out of the carrier groups was a considerable 

weakening of their shipboard air and antisubmarine defenses. This seems to have 

been too high a risk to take, because there was no way of knowing prior to the 

actual engagement between the carriers how effective the Japanese pilots would 

be. Normally, the operational commanders should not direct changes in task organization. If such changes are made, it is necessary to find a balance between offensive 

capabilities and the absolute necessity to defend and protect the friendly operational 

center of gravity adequately.

Spruance’s assumption that the enemy would first use carriers and then heavy 

surface ships was not plausible unless the initial carrier engagement ended in a 

Japanese victory. Only then would Ozawa be able to finish off the remnants of TF 

58 with battleships and other surface combatants. 

Spruance’s message to Mitscher and Lee in the late afternoon of 17 June gave 

them significant freedom in the dispositions and movements of their respective 

forces. Yet in the course of the operation Spruance made many tactical decisions 

that were clearly the responsibilities of Mitscher and Lee. The problem was perhaps 

that Spruance’s flagship at that point, the cruiser Indianapolis, was in TG 58.3, of 

which Mitscher’s flagship, the carrier Lexington, was also a part. The result was 

contrary to Spruance’s usual style of delegating authority to tactical commanders. Operational commanders should generally avoid making tactical decisions and 

thereby usurping the authority and responsibility of subordinate commanders. The 

only exception is if decisions of a subordinate could endanger the entire operation or 

that of an adjacent commander. In such a case, the operational commanders are duty 

bound to reverse the decision. Normally, area or numbered-fleet commanders should 

have headquarters ashore, with much better opportunities to evaluate the operational 

situation and less temptation to make tactical decisions.

Spruance’s most important, and also the most controversial, decision was not 

to let TF 58 steam too far westward during the night hours and thereby, Spruance 

feared, possibly allow part of the enemy fleet to get around behind and attack the 
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amphibious shipping off Saipan. Yet Spruance repeatedly misinterpreted the enemy’s intentions. Initially, Spruance and many of his subordinate task force commanders (but not Mitscher) believed that the Japanese would not commit their 

fleet to oppose a U.S. invasion of the Marianas, probably because they had not 

committed their fleet in defense of the Gilberts or Marshalls. Spruance’s second 

misinterpretation was his firm belief that part of Ozawa’s force would try to make 

an end run. Spruance was clearly influenced in that respect by his study of the 

captured plan for the Z operation; also, several messages from JICPOA and Nimitz 

referred to the possibility. He also believed that, having talked to some Japanese officers prior to hostilities, he knew the Japanese navy’s way of war. Even reports by 

submarines on the location of Ozawa’s fleet were not enough to change his decision 

on 18–19 June. In contrast, Ozawa correctly analyzed the situation and concluded 

that Spruance, as a cautious commander, would not venture far to the westward 

beyond Saipan’s beaches. In making their decisions, operational commanders should 

assess the enemy’s possible options on the basis of capabilities, not intentions. The only 

exception is when an operational commander has positive knowledge of the enemy’s 

plans. 

Spruance had many admirable qualities as a naval operational commander. 

However, he was cautious (as Ozawa correctly noted) and averse to high risk. He 

also probably interpreted too narrowly the mission of his fleet. An admiral with 

Nelson’s boldness and energy would have undoubtedly acted differently than 

Spruance did. But at the same time, such an admiral would have taken very high 

risks—and also the responsibility, had he failed.

Spruance’s decision brought severe criticism shortly after it was made. He was 

criticized especially by the aviators on Nimitz’s staff. They believed that Spruance 

had essentially tied the carriers to the beaches and thereby prevented them from 

achieving a much larger victory. From a purely tactical perspective, such criticism 

is not without merit. However, Spruance was an operational commander, and his 

overall responsibilities were much greater. The United States was conducting a major amphibious landing, and TF 58 was there to provide distant (or operational) 

cover and support. This meant that TF 58 had to operate within a supporting distance of the amphibious forces on and near Saipan; to do otherwise would incur 

too much risk. 

Normally, a major opposed amphibious landing would require the attacker to 

obtain at least local control of the surface and associated airspace. However, the 

situation in Operation FORAGER did not fit such a scenario. The U.S. force transited 

over an “uncommanded” sea and then landed on Saipan without any opposition 

by the enemy fleet. Toyoda activated the A-Go operation only on 13 June, after 

becoming convinced that the U.S. carrier strikes were not a raid but a prelude to an 

invasion of the southern Marianas; at that time his fleet was some 1,900 miles away. 
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Only after it sortied was it possible for Spruance to prepare for a decisive engagement. Inherent in such a situation was that the stronger fleet would be operationally on the defensive, while the weaker fleet would be on the offensive. The Fifth 

Fleet already possessed de facto local sea control of the surface and the air on 19–20 

June. Its mission was to deny that control to the enemy and thereby protect U.S. 

forces on the beaches and off Saipan. Nimitz and Spruance should have delayed 

the landings on Saipan for a few days after learning from radio intercepts on 13–14 

June that Toyoda had activated the A-Go operation; then there would have been 

no limitations on TF 58’s movements and actions. Also, the Fifth Fleet would have 

been in a position to go over to the offensive.

The A-Go operation, or the battle of the Philippine Sea, is yet another of the numerous historical examples that show the importance of a proper balance between the 

material and human elements of the factor of force in achieving victory in combat 

and in a war as a whole. While superiority in materiel, numerical and qualitative, is 

often a critical factor, it is much more important to possess superiority in elements 

that are hard or impossible to quantify—that is, the education, training, and skill of 

leaders and subordinates, will to fight, morale, discipline, and unit cohesion. The 

human element in war is of inestimable and timeless value and importance, but it is 

often underestimated or even ignored in our information age. Yet experience conclusively shows that wars are fought and won by humans, not machines, no matter 

how advanced they are. 
ABOUT THE AUTHOR 

Dr. Milan Vego has been a professor in the Joint Military Operations Department 

at the U.S. Naval War College, Newport, Rhode Island, since August 1991. A native 

of Bosnia and Herzegovina, he obtained political asylum in the United States in 

1976. Dr. Vego has been an adjunct professor at the Defense Intelligence College 

(1984–91) and a senior fellow at the Center for Naval Analyses in Alexandria, Virginia (1985–87), and at the former Soviet Army Studies Office, Fort Leavenworth, 

Kansas (1987–89). He earned a BA (1970) in modern history and an MA in U.S./

Latin American history (1973) at the University of Belgrade and his PhD in European history from the George Washington University (1981). He holds a license 

as a master mariner. Dr. Vego has published eight books, including the textbooks 

Operational Warfare (2001) and Joint Operational Warfare: Theory and Practice

(2008; reprint 2009), as well as The Battle for Leyte, 1944: Allied and Japanese Plans, 

Preparations, and Execution, and numerous articles in professional journals. He 

published his most recent book, Operational Warfare at Sea: Theory and Practice,

in December 2008. 

NAVAL WAR COLLEGE HISTORICAL MONOGRAPH SERIES

1. The Writings of Stephen B. Luce, edited by John D. Hayes and John B. 

Hattendorf (1975).

3. Professors of War: The Naval War College and the Development of the Naval 

Profession, Ronald Spector (1977). 

4. The Blue Sword: The Naval War College and the American Mission, 1919–1941,

Michael Vlahos (1980). 

5. On His Majesty’s Service: Observations of the British Home Fleet from the Diary, 

Reports, and Letters of Joseph H. Wellings, Assistant U.S. Naval Attaché, London, 

1940–41, edited by John B. Hattendorf (1983). 

7. A Bibliography of the Works of Alfred Thayer Mahan, compiled by John B. 

Hattendorf and Lynn C. Hattendorf (1986). 

8. The Fraternity of the Blue Uniform: Admiral Richard G. Colbert, U.S. Navy and 

Allied Naval Cooperation, Joel J. Sokolsky (1991). 

9. The Influence of History on Mahan: The Proceedings of a Conference Marking 

the Centenary of Alfred Thayer Mahan’s The Influence of Sea Power upon History, 1660–1783, edited by John B. Hattendorf (1991). 

10. Mahan Is Not Enough: The Proceedings of a Conference on the Works of Sir Julian Corbett and Admiral Sir Herbert Richmond, edited by James Goldrick and 

John B. Hattendorf (1993). 

11. Ubi Sumus? The State of Naval and Maritime History, edited by John B. 

Hattendorf (1994). 

12. The Queenstown Patrol, 1917: The Diary of Commander Joseph Knefler Taussig, 

U.S. Navy, edited by William N. Still, Jr. (1996). 

13. Doing Naval History: Essays toward Improvement, edited by John B. Hattendorf 

(1995). 
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14. An Admiral’s Yarn, edited by Mark R. Shulman (1999). 

15. The Memoirs of Admiral H. Kent Hewitt, edited by Evelyn Cherpak (2004). 

16. Three Splendid Little Wars: The Diary of Joseph K. Taussig, 1898–1901, edited 

by Evelyn Cherpak (2009).

17. Digesting History: The U.S. Naval War College, the Lessons of World War Two, 

and Future Naval Warfare, 1945–1947, Hal M. Friedman (2010).

18. To Train the Fleet for War: The U.S. Navy Fleet Problems, 1923–1940, Albert A. 

Nofi (2010).

19. Talking about Naval History: A Collection of Essays, John B. Hattendorf (2011).

20. New Interpretations in Naval History: Selected Papers from the Sixteenth Naval 

History Symposium Held at the United States Naval Academy 10–11 September 

2009, edited by Craig C. Felker and Marcus O. Jones (2012).

21. Blue versus Orange: The U.S. Naval War College, Japan, and the Old Enemy in 

the Pacific, 1945–1946, Hal M. Friedman (2013).