# Operation Downfall order of battle

Operation Downfall was the proposed Allied plan for the invasion of the Japanese home islands near the end of World War II.
The operation had two parts, Operation Olympic, intended to capture the southern third of the southernmost main Japanese island, Kyūshū, and Operation Coronet, the planned invasion of the Kantō Plain, near Tokyo, on the main Japanese island of Honshu. Olympic was scheduled for November 1945, to be followed by Coronet in early 1946.
If Downfall had taken place, it would have been the largest amphibious operation in history, surpassing D-Day. The planned operation was canceled when Japan surrendered following the atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and the invasion of Manchuria.

## Order of Battle for Olympic
### Allied

Supreme Commander, Allied Forces Pacific General Douglas MacArthur

#### Ground forces

Should these four corps prove insufficient to accomplish the tasks assigned, elements earmarked for Coronet would be used to reinforce Sixth Army at the rate of three divisions per month beginning about 30 days after the initial landings.
    Sixth Army
    General Walter Krueger
       Peripheral landings
          40th Infantry "Sunburst" Division (Landing on Yakushima and Koshikijima Islands)
          158th Infantry Regiment (Landing on Tanegashima)
       I Corps (Landing at Miyazaki)
       Major General Innis P. Swift
          25th Infantry "Tropic Lightning" Division
          33rd Infantry "Illinois" Division
          41st Infantry "Sunsetters" Division
       V Amphibious Corps (Landing at Kushikino)
       Major General Harry Schmidt, USMC
          3rd Marine Division (Bougainville, Guam, Iwo Jima)
          4th Marine Division (Kwajalein, Saipan/Tinian, Iwo Jima)
          5th Marine Division (Iwo Jima)
       XI Corps (Landing at Ariake)
       Major General Charles P. Hall
          1st Cavalry Division
          Americal Division
          43rd Infantry "Winged Victory" Division
       IX Corps (Reserve afloat)
       Major General Charles W. Ryder
          81st Infantry "Wildcat" Division
          98th Infantry "Iroquois" Division
       Follow-up units:
          11th Airborne Division
          77th Infantry Division

#### Naval forces

    Third Fleet
    Admiral William F. Halsey
       20 fleet and light aircraft carriers
       9 battleships
       26 cruisers
       75 destroyers
       incl. British Pacific Fleet
          6 fleet and light carriers
    Fifth Fleet
    Admiral Raymond A. Spruance
       36 escort carriers
       11 battleships
       26 cruisers
       387 destroyers and destroyer escorts
       394 AKA, AP, APA, APD, APH
       977 LSD, LSM, LST, and LSV
    Seventh Fleet
    Admiral Thomas C. Kinkaid

#### Air forces

    Far East Air Forces
    General George C. Kenney (119,000 men) – 14 bomber groups, 10 fighter groups
       Fifth Air Force
       Seventh Air Force
       Thirteenth Air Force
    United States Strategic Air Forces in the Pacific
    General Carl A. Spaatz
    Major General Curtis E. LeMay
       Twentieth Air Force (Lt. Gen. Nathan Twining) (77,000 men)
          1,000 B-29 Superfortresses
       Eighth Air Force (Lt. Gen. Jimmy Doolittle)
    Commonwealth forces
       Tiger Force (detached from RAF Bomber Command):
          480–580 Avro Lancaster bombers (about half to be used as tankers for in-flight refuelling)
       Australian First Tactical Air Force
          20 fighter/attack squadrons from the Royal Australian Air Force

### Japan
#### Ground forces

    Second General Army
    Field Marshal Shunroku Hata
       Sixteenth Area Army
       Lieut. General Yokoyama Isamu (600,000 men)
          Northern Kyūshū — 56th Army
          Lieut. General Ichiro Shichida (365,000)
             145th Division
             312th Division
             351st Division
             124th Independent Mixed Brigade
             57th Division (20,000 men)
             4th Tank Brigade
          Southeastern Kyūshū — 57th Army
          Lieut. General Nishihara Kanji (150,000 men)
             Tanegashima—109th Independent Mixed Brigade (5,900 men)
             Miyazaki—154th Division, 156th Division, 212th Division (55,000 men)
             Ariake—86th Division, 98th Independent Mixed Brigade, 1 regiment, 3 infantry battalions (29,000 men)
             25th Division, 5th Tank Brigade, 6th Tank Brigade
          Southwestern Kyūshū — 40th Army
          Lieut. General Nakazawa Mitsuo (85,000 men)
             303rd Division (12,000 men) (Sendai)
             206th Division (Fukiage)
             146th Division, 125th Independent Mixed Brigade (S. Satsuma Peninsula)
             77th Division 1 tank regiment
          216th Division 4 brigades

#### Air forces

    Air General Army
    General Masakazu Kawabe
       Sixth Air Army — Kyūshū
          5,000 aircraft assigned as kamikazes, 5,000 aircraft available for kamikaze service, 7,000 aircraft in need of repair
       100 Koryu-class midget submarines, 250 Kairyu-class midget submarines, 1,000 Kaiten manned torpedoes, 800 Shinyo suicide boats

## Order of Battle for Coronet
### Allied
#### Ground forces

    First Army
    General Courtney H. Hodges
       III Amphibious Corps
          1st Marine Division (Guadalcanal, Peleliu, Okinawa)
          2nd Marine Division (Tarawa, Saipan, Okinawa)
          6th Marine Division (Okinawa)
       XXIV Corps
          7th Infantry "Bayonet" Division
          27th Infantry "New York" Division
          96th Infantry "Columbia" Division
    Eighth Army
    Lieut. General Robert L. Eichelberger
       X Corps
          24th Infantry "Taro" Division
          31st Infantry "Dixie" Division
          37th Infantry "Buckeye" Division
       XIV Corps
          6th Infantry "Red Star" Division
          32nd Infantry "Red Arrow" Division
          38th Infantry "Cyclone" Division
       XIII Corps (Reserve afloat)
          13th Armored Division
          20th Armored Division
    United States Army Forces Pacific reserve
       97th Infantry "Trident" Division
Thirty days after the initial assault, each army would be reinforced by a corps of 3 divisions. Five days later an airborne division and a United States Army Forces Pacific Reserve Corps of 3 divisions would be made available. Strategic reserve for the entire operation would consist of a corps of 3 divisions located in the Philippines and divisions from the United States to permit reinforcement at the rate of 4 per month.

#### Unsourced listing of the aforementioned reinforcements

    For First Army
       Unnamed follow-on corps
          5th Infantry Division
          44th Infantry Division
          86th Infantry Division
    For Eighth Army
       Unnamed follow-on corps
          4th Infantry Division
          8th Infantry Division
          87th Infantry Division
    United States Army Forces Pacific reserve
       11th Airborne Division
       Unnamed follow-on corps
          2nd Infantry Division
          28th Infantry Division
          35th Infantry Division
       Strategic reserve
          91st Infantry Division
          95th Infantry Division
          104th Infantry Division
    British Commonwealth Ground Forces
       Commonwealth Corps (Lt. Gen. Charles Keightley)
          3rd Infantry Division (United Kingdom)
          6th Infantry Division (Canada)
          10th Infantry Division (Australia)

### Japan

All Japanese formations on Honshu were badly understrength and lacking in equipment. The American First Army's landings would likely have been opposed by the Japanese 52nd Army and the Eighth Army's landings by the Japanese 53rd Army.
    First General Army
    Field Marshal Hajime Sugiyama
       Twelfth Area Army
       General Shizuichi Tanaka
          36th Army – Urawa, Saitama
             81st Division
             93rd Division
             201st Division
             202nd Division
             206th Division
             214th Division
             1st Tank Division
             4th Tank Division
          51st Army – Tsuchiura, Ibaraki
             44th Division – Ogawa
             151st Division – Mito
             221st Division – Kashima
             115th Independent Mixed Brigade – Shibasaki
             116th Independent Mixed Brigade – Hokota
             7th Independent Armored Brigade – Ogawa
          52nd Army – Sakura, Chiba
             3rd Imperial Guards Division – Naruto
             147th Division – Mobara
             152nd Division – Choshi
             234th Division – Sōsa
             3rd Independent Armored Brigade
             8th Artillery Headquarters
          53rd Army – Isehara, Kanagawa
             84th Division – Odarawa
             140th Division – Kamakura
             316th Division – Isehara
             117th Independent Mixed Brigade – Numazu
             2nd Independent Armored Brigade – Tsudanuma
             11th Artillery Headquarters – Hiratsuka
          Tokyo Bay Garrison – Choshi, Chiba
          321st Division – Tokyoa