U.S.S. THORNBACK (SS-418) — war patrol report SS-418_THORNBACK.pdf

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START OF REEL
JOB NO. [HANDWRITTEN: H-108]
OPERATOR [HANDWRITTEN: M. Monroe]
DATE [HANDWRITTEN: 2/13/80]

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THIS MICROFILM IS
THE PROPERTY OF
THE UNITED STATES
GOVERNMENT

[SEAL: DEPARTMENT OF DEFENSE, UNITED STATES OF AMERICA]

MICROFILMED BY
NPPSO-NAVAL DISTRICT WASHINGTON
MICROFILM SECTION

REEL TARGET - START AND END
NDW-NPPSO-5210/1 (6-78)

— page 2 —
[HANDWRITTEN: THORN BACK (SS-418)]
[HANDWRITTEN: WORLD WAR II PATROL FILE]

[HANDWRITTEN: ALL MATERIAL ON THIS REEL IS DECLASSIFIED]

[HANDWRITTEN: FOR DECK LOGS OCTOBER 1944 - JUNE 1945 CONSULT]
[HANDWRITTEN: NATIONAL ARCHIVES WHICH HAS CUSTODY.]

[SIGNATURE: J.A. KOONTZ]

— page 3 —
Thornback
A slender member of the shark family native to northern
Atlantic waters ranging from the temperate to the arctic. The
Thornback has a long, pointed snout and a sharp spine at the end
of each dorsal fin.

(SS-418: dp. 1,570 (surf.), 2,415 (subm.); l. 311'8"; b. 27'3";
dr. 15'5"; s. 20.25 k. (surf.), 8.75 k. (subm.); cpl. 81; a. 10 21"
tt., 1 5"
1 40mm., 1 20mm.; cl. Balao)

Thornback (SS-418) was laid down on 5 April 1944 by the
Portsmouth (N.H.) Navy Yard; launched on 7 July 1944; sponsored
by Mrs. Peter K. Fischler; and commissioned on 13 October 1944,
Comdr. Ernest P. Abrahamson in command.

Thornback stood out of New London, Conn., on 20 March 1945
bound, via the Panama Canal, for the Hawaiian Islands. She
arrived at Pearl Harbor on 25 May and conducted training in
Hawaiian waters prior to getting underway on 11 June for the
western Pacific. As she stood down the Pearl Harbor channel, a
formation of LCI's, running down the wrong side of the channel
forced Thornback to crowd dangerously near the extreme edge
of the channel. In the process, the submarine damaged her sound
dome, necessitating repairs and a two-day delay in departing.
She set sail for Saipan on the 13th, but she was rerouted to
Guam. En route to the Marianas, Thornback conducted an average of
four training dives daily, in conjunction with battle problems,
drills, and emergency surfacing exercises, before she arrived at
Guam on 25 June.

— page 4 —
As lead ship of a wolf pack nicknamed "Abe's Abolishers."
Thornback stood out to sea on 30 June, bound for the Japanese home
islands. By this point in the war, American and British task
forces were within easy gun range of Japanese coastal targets
with near impunity. Japan's merchant marine and Navy had dwindled
in size. Allied submarines and aircraft had taken an ever increasing
toll. In the air, Japan's once vaunted air forces had been struck
from the skies. Sweeping ahead of 3d Fleet Task Forces, the
"Abolishers" made antipicket boat sweeps in the Tokyo-Yokohama
area before proceeding to hunting grounds off the east coast of
Honshu and south of Hokkaido.
Rough seas, strong winds, and generally poor visibility prevailed
during Thornback's patrol. She sighted a hospital ship on 5 July
and let it pass. Six days later, a minor fire in the pump room
caused a temporary shutdown in the number one plant before swift
repairs enabled the ship to continue as before.
On the 15th, Thornback sighted Sea Poacher (SS-406), and
the two boats exchanged information on their hunting areas. They
also swapped movies, precious commodities for boosting morale on
board the crowded submersibles. Six days later, Thornback proceeded
north to patrol off Erimo Seki, an area which had recently seen a
series of devastating carrier raids by Admiral William F. Halsey's
Fast Carrier Task Force 38. The submarine's commanding officer
noted somewhat humorously,
"This area should be about as heavily travelled
as the Sahara Desert after the working over it just had..."

— page 5 —
His assessment was correct--only straggling merchantmen and
small patrol craft hugged the barren coasts. On 26 July, at 0320,
Thornback submerged 8,000 yards off Hei Saki. At 0403, the
submarine's sound gear picked up the "pinging" projected by a
snooping Japanese escort ship, and she came to periscope depth to
have a look.
Carefully maneuvering into position, Thornback fired one shot
from her stern tubes at 0429; and soon heard a small explosion
which stopped the enemy's screws. Almost immediately the
submariners picked up new sounds--two more escorts, "pinging"
and coming aggressively closer. After sizing up the new attackers,
Thornback felt that they were too small to use a torpedo on--
besides, a Japanese floatplane had begun circling the area. A
rowboat with a few Japanese sailors amidst a pile of flotsam
testified to the fact that the first ship was no longer there.
Satisfied that their quarry had been sunk, the submarine cleared
the area. One of the other escorts gave up the chase and picked
up survivors of her sunken sister. "All antisubmarine vessels
have closed the beach," Thornback's commander later recorded,
"and seem to be pinging away at the rocks."

— page 6 —
Three days later by periscope, the submarine spotted a
950-ton "sea truck," similar to Sanko Maru, at 2,000 yards, close
inshore. Unescorted, the Japanese presented a tempting target for
a gun attack, but no sooner had Thornback's periscope shown and
bow broke the surface, than the target slipped into the misty
weather. Not to be daunted, Thornback followed, playing a cat and
mouse game and fired five torpedoes. All missed! She later
sighted the enemy again, missed with three more torpedoes, and
took the "sea truck" under fire. Despite poor visibility, Thornback
closed to 300 yards and scored numerous hits with the 40-millimeter
guns. The target however, was able to move closer inshore and
escaped in the fog which closed around her like a shroud.
The submarine lurked on the surface off Hokkaido on 31 July,
and again tangled with some of the numerous Japanese patrol craft.
She sighted a 100-foot patrol boat at 500 yards and closing.
Thornback's five-inch deck gun was trained out, but her crew could
not keep their sights on the attacker through the telescopes and
switched to open sights. Meanwhile, the 40-millimeter gun opened
a devastating barrage at the enemy craft as it came steadily on a
collision course. These shells continually hit the escort ship
along the waterline and in the pilot house, probably killing the
occupants on the bridge.

— page 7 —
Thornback had passed her target once at 300 yards and came
about for a second pass when the forward torpedo room reported
sharp noises forward. Further amplification showed that the noise
was caused by enemy machine gun bullets striking the submarine's
hull. Resuming the attack, Thornback swung back into action, with
visibility only 300 yards and lessening. Her 40-millimeter fire
continued to maul the Japanese vessel, shooting away one of her
masts and leaving her limping shoreward at only 3 knots. After
securing from battle stations, Thornback passed through an
oil slick and noted a mast from the heavily hit patrol craft.

Later on the 31st, Thornback rendezvoused with Sea Poacher
off Kessennuma and proceeded north to pick up Angler (SS-240)
en route to a projected shore bombardment mission against Hokkaido.
The sight of the three submarines cruising on the surface moved
Thornback's commander to write: "On this clear and sunny day, the
three ships in perfect column on a flat sea made a beautiful
picture tearing along at 18.5 knots."

— page 8 —
At 1402 on 1 August, this part of "Abe's Abolishers"--
Thornback, Angler and Sea Poacher--made landfall off their target
at Urakawa, Hokkaido. They swung parallel to the beach with
guns manned and ready. Twelve minutes later, slowing to 10 knots,
Thornback and her consorts opened fire with five-inch and
40-millimeter batteries at a range of 4,200 yards. The first few
rounds from Thornback's five-incher went wild, but the crew soon
locked onto the range. Firing by hand after the foot firing
plunger broke off, Thornback's gunners eventually
sent 100 rounds of five-inch shells shoreward, heavily damaging
a factory and a power plant. "The firing took 22 minutes and was
of inestimable value to the entire crew," wrote the submarine's
commanding officer. "The training was excellent and the boost
to morale tremendous."

Thornback set sail for Midway after the gunning of Urakawa,
and arrived at the atoll on 8 August. Seven days later, Japan--
hemmed in by veritable armadas of Allied ships and planes which
were able to roam almost at will and unchallenged off her coasts
and in her skies--surrendered.
Thornback soon returned to the United States, where she was
decommissioned at New London on 6 April 1946 and was placed in the
Atlantic Reserve Fleet. Subsequently brought to Portsmouth Naval
Shipyard, she was converted and reactivated as a Guppy II-A. On
2 October 1953, the submarine was recommissioned, Lt. Comdr.
Thomas C. Jones, Jr., in command, and assigned to Submarine Squadron
(SubRon) 4.

— page 9 —
Shaking down in her new configuration, the submarine performed
a "first" for submarines on 6 November 1954, when she snorkeled
in the Mississippi River at New Orleans from the Industrial Canal
to the foot of Canal Street. With SubRon 4, the ship based at
Key West, Fla., and visited Caribbean ports before entering the
Charleston (S.C.) Naval Shipyard in February 1956 for overhaul.
Upon completion of this work, the submarine was deployed to the
Mediterranean for a tour with the 6th Fleet before returning to
Key West in March 1957. While with SubRon 4, Thornback participated
in operations supporting the Operational Development Force, the
Fleet Sonar School, and the Fleet Training Unit at Guantanamo Bay,
Cuba.

On 2 June 1958, Thornback departed the Caribbean, bound for
Londonderry, Northern Ireland, and operations with the joint Royal
Navy-Royal Air Force antisubmarine school. While thus engaged,
the submarine damaged her port propellor at Derry and became the
first American submarine to be docked at Faslane by the Royal Navy.
Thornback returned to the 6th Fleet and her second Mediterranean
deployment which lasted from 2 July to 24 September 1958.

— page 10 —
For the remainder of the ship's active career, she was
based out of Charleston, conducting deployments to the North
Atlantic, the Mediterranean, and to the Caribbean, and operating
in a support capacity as newer submarine types joined the Fleet.
Placed in a reduced-manning status on 14 April 1971, the ship
was turned over to the Turkish Navy on 1 July 1971, and renamed
Uluc Ali Reis (S-338). Decommissioned from the United States
Navy on that same date, she was later struck from the Navy list
on 1 August 1973.
Thornback received one battle star for her World War II
service.

— page 11 —
SS418/A16-3
Serial (032)

U.S.S. THORNBACK (SS418)
c/o Fleet Post Office,
San Francisco, California.

DECLASSIFIED ART. 0445, OPNAV August 1945.
BY [HANDWRITTEN: J.M.G.A] DATE [HANDWRITTEN: 9/20/72]

[STAMP: DECLASSIFIED]
From: The Commanding Officer.
To : The Commander in Chief, UNITED STATES FLEET.
Via : (1) The Commander Submarine Division THIRTY TWENTY ONE.
(2) The Commander Submarine Squadron THIRTY TWO.
(3) The Commander Submarine Force, PACIFIC FLEET.

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

Enclosures: (A) Subject Report.
(B) Track Charts.

1. Enclosure (A), covering the first war patrol of this vessel
conducted in the areas east of HONSHU and south of HOKKAIDO during the
period 13 June 1945 to 8 August 1945, is forwarded herewith.

[SIGNATURE: E. T. ABRAHAMSON]
E. T. ABRAHAMSON.

[HANDWRITTEN: FILMED]
[HANDWRITTEN: 138401]

— page 13 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L
Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

— page 14 —
SS:18/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

NARRATIVE

Officers on Board
Commander Ernest P. Abrahamson, USN
Lieut-Comdr. Clarence E. Bell, Jr., USN
Lieutenant Benjamin Hinman, USNR
Lieut(jg) Robert L. Hovis, Jr., USNR
Lieut(jg) Irvin A. Clough, USN
Lieut(jg) Everett J. Macartney, USNR
Lieut(jg) Laurence H. Turner, USN
Ensign Robert S. Perew, USNR
Ensign Ernest R. Barrett, USN
Torpedoman Melvin B. Smith, USN

Chief Petty Officers
CARRILLO, Hidalgo CPHM, USNR
FITZPATRICK, John J. CCM, USN
FRAZIER, George McM. CPhOM, USN
GUTTERMUTH, John G. CEM, USN
MAUTINO, John B. CEM, USN
MORGAN, Ross N. CTM, USN
SNELL, Martin G. CMOMM, USN

(PRIOR TO THIS PATROL)
Number of War Patrols
1
5
1
0
0
10
0
0
0
7

(PRIOR TO THIS PATROL)
Number of War Patrols
1
6
0
11
0
8
5

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SS418/A16-3
Serial (032)
C-O-N-F-I-D-E-N-T-I-A-L
Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

11 June 1945
1330 VW Underway on first war patrol.
1400 VW Returned to Base for replacement of sound dome damaged when Thornback
         was forced to extreme edge of channel by fifteen LCI's coming down
         the wrong side of the channel in confusion.

13 June 1945
1300 W Underway on first war patrol enroute Saipan.
1757 W Made trim dive.

         While enroute, an average of four training dives were made daily.
         Battle problems, battle surfaces, and emergency drills were conducted
         in conjunction. Qualification of officers and men was pressed.
         1200 positions follow:

14 June W Lat. 21-06 N Long. 163-30 W

15 June X Lat. 21-12 N Long. 168-44 W

16 June X Lat. 21-03 N Long. 173-44 W

17 June Y Lat. 21-16 N Long. 179-54 W

18 June Omitted.

19 June L Lat. 21-02 N Long. 174-08 E

20 June L Lat. 21-15 N Long. 168-31 E (Orders received changing destination
         to Guam).

21 June L Lat. 21-02 N Long. 163-12 E

22 June K Lat. 19-29 N Long. 157-33 E
1730 K Sighted and joined up with SEA POACHER. Proceeded in company.

23 June K Lat. 18-27 N Long. 151-40 E

24 June 1945
0740 K Sighted Alamagan Island bearing 254 T, distant 47 miles.
0830 K Sighted PAGAN ISLAND bearing 284 T, distant 46 miles.
0940 K Sighted GUGUAN ISLAND bearing 219 T, distant 44 miles.
1200 K Lat. 17-40.3 N Long. 145-46 E

- 4 -

— page 16 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

— page 17 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

— page 18 —
SS/18/A4-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

5 July 1945 (Continued)
0253 SD contact 10 miles.
0503 Sighted floating mine Lat. 29-45 N Long 141-24 E. Fired .50 cal.
     and 40mm. Obtained two hits, but unable to sink mine.
0810 Sighted plane distant 10 miles.
0850 Sighted two planes crossing bow, range 12 miles.
1200 Lat. 29-23N Long 142-50 E.
1300 Sighted mine Lat. 29-21 N. Long 143-04 E. Fired 20mm and .50 cal.
     Unable to sink mine.

6 July 1945 (Proceeding to initial sweep position.)
1058 Submerged on definite periscope sighting bearing 030T range uncertain.
     Changed course away. No sound contact. #1 Main outboard exhaust valve
     apparently did not close all the way as the exhaust elbow flooded.
1113 Surfaced on four main engines and opened out to southward.
1200 Lat. 28-42 N. Long. 146-41 E.
1755 Hear planes talking on VHF.
1900 In vicinity of Esquire, commenced patrolling to northwestward at
     one engine speed. SD contact at 18 miles. Talked to plane on VHF.
2324 APR contact on 117 mcs. Must be friendly sub.

7 July 1945
     Making day search of sweep area we will pass through tonight, to
     make sure nothing sneaks by after dark.
0355 SJ contact - 220T 13,000 yards.
0420 Exchanged calls and recognition signals with CERO.
0800 Reversed course to southeast to sweep back toward initial point.
1138 APR contact - 201 mcs.
1139 Sighted PBM bearing 180T, estimated range at least 25 miles. SD
     made contact at 20 miles 5 minutes later. The lookout have any
     number of times picked up friendly planes before SD at ranges well
     in excess of 20 miles. The opinion of all the experienced officers
     on board is that the performance of our lookout system, having
     PEARL in exceptionally outstanding. It has given us great confi-
     dence in the Lookout Training Schools and in our own lookout system.
1152 SJ made contact on plane at 22,000 yards.
1155 Exchanged recognition signals with plane.

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— page 19 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol,

7 July 1945 (Continued)
1200 Lat. 29-34 N Long. 146-42 E.
1247 APR contact - 115 mcs. PRF 60. Probably friendly SD.
1330 Sighted submarine bearing 160T, distance about 8 miles. Looks like
U.S.
1331 Sighted another sub bearing 169T, range about the same. Also looks
like U. S.
1400 Identified subs as MORAY and KINGFISH. Closed to hailing distance
and gave them instructions via loud hailer for patrolling after first
sweep.
1500 Parted company with MORAY and KINGFISH.
1700 SJ radar interference bearing 195T. Changed course to 195T.
1725 Commenced challenging on SJ.
1729 Sighted shears of friendly sub bearing 205T.
1735 Exchanged SJ signals, so closed SEA POACHER to pass instructions.
1800 Sighted another friendly sub bearing 260T and exchanged recognition
signals with ANGLER.
1840 Completed passing instructions to both vessels and opened out to our
initial point on four engines to start sweep. Have seen all
Abolishers except CARP today. Asked KINGFISH this morning to pass
the instructions on to her. Did not want to use radio.
2300 Made contact with MORAY. Got rough fix by Loran and found we were
eastward and MORAY was to westward. We both opened out.

8 July 1945
Conducted anti-picket boat sweep to northwestward.
0435 SD contact 16 miles - shows IFF.
0500 Visibility decreasing, sea rising slightly, haze forming around
horizon. Weather generally squally. Sweeping every ten minutes with
SJ; shifting to continuous sweep during showers.
1200 Lat. 30-44 N Long. 145-30 E.
1239 APR contact - 115 mcs on port side. Believed to be ANGLER.
1452 Sighted U. S. type submarine bearing 202T, distance 8 miles. Should
be ANGLER.

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— page 20 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

— page 21 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

10 July 1945 (Continued)
1207 Sighted plane bearing 084T, 5° elevation which appeared on the SD at
1208 and was coming in with a zero angle on bow.
1209 Submerged. Plane appeared to be a privateer.
1533 Headed to southwest at four engine speed searching.

1635 Commenced patrolling.
1647 Heard unintelligible voice transmissions on SCR-610.
1700 Received contact report from KINGFISH reporting 3 columns of smoke 100
miles to northeast of us. No course or speed given.

1817 Sighted U. S. type submarine bearing 252T and shortly after a sur-
prising range of 18,000 yards. Exchanged recognition signals via SJ
with ANGLER.
1857 Commenced patrolling to northeastward.

2230 Broke off search and headed for patrol sector off KINKASAN.

11 July 1945
Patrolling north and south between 37-40 N and 38-00 N along eastern
edge of restricted area. Heavy overcast, no sights. Searching for
aviators or flare signals. Aviators have been reported down in re-
stricted area. Taking sounding every fifteen minutes.
0004 Fire in the pump room.
0006 Fire under control. Fire was in #1 air conditioning control panel.
#1 plant out of commission to replace burned insulation.
0029 SJ radar interference bearing 029T. Looks like friendly radar. Can
faintly hear voices on SCR-610. Interference continued for about an
hour and a half while we headed westward. Should be MORAY in area to
north of us.
0309 SJ contact bearing 254T, range 31,200 yards.
0323 Now have two pips. Others fade in and out. Stationed tracking party.
0414 Secured tracking party. Had targets on 090 and reverse at a variety
of speeds before we finally determined targets were second sweep
echoes on high land back of KINKASAN ISLAND.

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SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L
Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

11 July 1945 (Continued)
0441 APR contact 150 mcs; PRF 400; FW 10 - land based. We have had this
     several times the last two days, and have found from our directional
     APR that this station appears to be on KINKASAN ISLAND. Every time we
     are close enough to this station for an APR indication we find that
     all we have to do is key the SD for a second or two and he immediately
     stops sweeping and tries to get a contact on us. We only use the SD
     now when we have an APR indication of increasing strength.
0525 SD contact 10 miles.
0527 Submerged when plane got in to 7 miles.
0606 JT reported he had possible pinging bearing 312T. Nothing in sight at
     60 feet. Came up to 50 feet. Still nothing in sight.
0614 Surfaced, no contacts.
0743 APR contact 80 mcs, PRF 500, FW 55 - land based. Appears to be located
     near 37-20 N, 141-00 E.
0935 Sighted land bearing 336T identified as KINKASAN ISLAND.
1105 SD contact 16 miles. Submerged.
1135 Surfaced.
1138 Sighted two planes at about 6-7 miles headed for us. Submerged.
1200 Lat. 37-56 N, Long. 141-47 E.
1317 Surfaced and opened out to eastward.
1832 Slowed to 4 knots to work over bow planes which have become extremely
     noisy.

12 July 1945
     Patrolling east-west line between 37-40 N and 38-40 N keeping to east-
     ward of restricted area. Rough seas, strong winds, heavy overcast,
     and poor visibility.
1200 Lat. 37-41 N, Long. 142-53 E.
1214 APR contact 115 mcs.
1240 SD contact 4 miles. Plane flew overhead and all hands on the bridge
     could hear the engines - visibility estimated 100 yards.

13 July 1945
     Patrolling 5 mile square in eastern part of area, covering possible
     TSUGARU-TRUK traffic route. Hoping a Jap sub might come this way.
     Rough seas, heavy overcast, rain and no sights for several days.

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— page 23 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) -- Report of First War Patrol.

13 July 1945 (Continued)
0445 SJ contact bearing 128T, range 8,000. Immediately after had indication
     of friendly SD on the APR. Exchanged SJ signals with ANGLER.
1200 Lat. 37-27 N, Long. 144-21 E.
1505 SJ interference bearing 150T.
1735 Sighted sub bearing 116T, range 7 miles. Identified as SEA POACHER.
1755 Sighted ANGLER bearing 220T, range 6 miles. Opened out to northwest.
1906 Sighted large blue opening in overcast up near horizon; headed for it on
     four main engines and subsequently obtained six star fix. Our first in-
     formation on our position in 3 days.
2031 Submerged on TDM contact bearing 315T. This looked awfully good on the
     chemical recorder, but could have been a porpoise. On diving, forward
     torpedo room reported unusual noise in vicinity of the tubes. This
     could have been the bow planes. Two men listened in with head sets on
     the TDM and both reported the sound was very much like a torpedo. We
     made best of recording for some one else to look at. Sound reported
     unclear bearing 330T. Headed in that direction running silent, but sound
     faded out after several minutes.
2210 Surfaced and opened out to northward. APR had an indication of friendly
     SD to eastward of us.

14 July 1945
     Patrolling to eastward toward initial point for second picket boat
     sweep.
0830 Received dispatch from ComSubsPac, delaying sweep one day.
0940 Headed to southeast to clear THORNBACK serial three.
1012 Sighted U. S. sub bearing 218T on horizon. Exchanged signals with
     ANGLER.
1200 Lat. 37-48 N, Long. 147-02 E.
1416 APR contact 200 mcs, PRF 60.
1830 Completed transmitting serial three after nine hours of trying to raise
     a station, and of finally pushing through all of the Jap jamming and
     interference.

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SS/418/A16-3
Serial (032)
C-O-N-F-I-D-E-N-T-I-A-L
Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

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SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L
Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

17 July 1945 (Continued)
1200 Lat. 32-57 N, Long. 143-10 E.
1333 Commenced patrolling east - west line at one engine speed. Commenced
     converting #3 and #5 F.B.T.'s.
1430 Conversion completed.
2040 Dove to flush out fuel ballast tanks.

18 July 1945
     Patrolling east and west south of 33°N in heavy seas and heavy overcast.
0908 Sighted Privateer.
1200 Lat. 32-40 N, Long. 143-28 E.
2100 Received ComSubPac's 180958 of July and increased speed to make good
     12 knots heading west.

19 July 1945.
     Running westward at two engine speed to get in area MOUTH carrying out
     orders to proceed north throught MOUTH and FURNACE to operating area.
1200 Lat. 34-03 N, Long. 140-52.0 E.
     Countless air contacts were made during the day and night, but none
     appeared to be unusual. Most were landbased, but one or two may have
     been airborne. No planes were sighted and no SD contacts were made
     despite the fact we were within 40 miles of the coast and 75 miles
     from Tokyo.

20 July 1945
     Running north on two main engines to commence patrol near ERIMO SAKI
     Usual heavy overcast.
1200 Lat. 36-12 N, Long. 142-52 E.
1940 Sent message on SAFPLAN to TREPANG to arrange a rendezvous and get any
     information they might have on our area. No receipt.
2304 Sent message again. No receipt.

21 July 1945
     Proceeding north to patrol off ERIMO SAKI. Entered area ONE and re-
     lieved Admiral Halsey and Third Fleet. This area should be as heavily
     travelled as the Sahara Desert after the working over it just had.

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21 July 1945 (Continued)
0730 SJ contact on land distant 30 miles. Believed to be peak back of
ERIKO SAKI. Closed and commenced patrolling 40 fathom curve east of
cape. Visibility 2000 yards.
1020 Dove for trim.
1100 Surfaced.
1200 Lat. 41-50 N. Long. 143-12 E.
1305 Changed course to northwestward to patrol 40 fathom curve on surface
to westward of cape.
1510 Fog lifted and showed us fishing village of HOROIZUMI KO very clearly
at 6,000 yards. Not so much as a fishing boat in sight.
1520 Submerged.
1927 Surfaced and headed back for ERIKO SAKI.
2316 Headed for SHIRIYASAKI.

22 July 1945
0258 Radar contact on SHIRIYA SAKI 245T range 55,000 yards.
0447 APR contact 100 mcs PRF 450 bearing puts it on SHIRIYA SAKI. Did not
steady on us.
0453 Submerged 8,000 yards from the beach southeast of SHIRIYA SAKI. Visi-
bility poor, rough seas, heavy rain. Ran west to 40 fathom curve and
then patrolled north and south. Came to 40 feet once an hour for
navigational fix using PPI.
1200 Lat. 41-23 N. Long. 141-32 E.
2005 Surfaced and opened out to northeast to patrol across entrance to
TSUGARU STRAITS

23 July 1945
0103 Patrolling TSUGARU STRAITS while charging batteries.
Headed back for SHIRIYA SAKI. As soon as we started back the radars
on SHIRIYA SAKI (100/450-475) and ESAN SAKI (148/400) would steady on
us with a strong signal each time we keyed the SJ. Secured the SJ
except for listening, and commenced searching with SJ. Only occasional
contacts with the two radar stations now.

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24 July 1945 (Continued)
0116 Target zigged right to 175T; range 9900.
0120 Lost contact by visual and radar at the same time. Last range 10,300
     yards. Changed course to 180T.
0123 Changed course to 200T.
0130 Held conference of officers on the bridge and in the conning tower and
     decided he must have submerged. Just before he disappeared he was
     very clearly visible in the binoculars and gave a good strong pip on
     the SJ. As we were now close to the spot where he dove, we changed
     course to 090T to clear the area.
0143 Set course for ERIMO SAKI.
0400 SJ land contact 025T, distance 40 miles.
0425 Frequent APR contacts on ESAN SAKI at 148 mcs.
0545 Sighted HOKKAIDO headlands bearing 337T.
0640 Submerged on 60 fathom curve and commenced closing coast for close
     patrol of coast to westward of ERIMO SAKI.
1200 Lat. 42-06 N, Long. 142-45 E. Not even the fishermen go to sea around
     here.
1845 Surfaced and headed south hoping to contact Jap sub when he surfaces.
2156 Second sweep SJ contact on ERIMO SAKI, 130,000 yards.

25 July 1945
     Weather is crystal clear and dry with full moon after 12 days of fog,
     rain and clouds.
0306 10 cm interference bearing 195T. Unable to identify definitely as SJ.
0708 10 cm interference bearing 210T. Looks like friendly SJ. Changed
     course to intercept.
0719 Sighted white object on horizon bearing 230T. Closed on four engines
     and soon identified as U.S. sub. In the clear early morning sunlight
     she looked as white as one of the United Fruit ships due to the light
     grey paint and the whitish haze on the horizon. Exchanged signals
     with SEA POACHER and went close aboard to pass over movies and area
     information.
0825 Headed for Area T.O.
1022 Sighted land bearing 270T, range 25 miles.
1200 Lat. 39-07 N, Long. 142-15E.
1226 Submerged 8 miles offshore east of KAMAISHI which the Third Fleet
     bombarded a few days ago. Weather still clear but hazy along the
     shore. Commenced closing coast at 120 feet to avoid detection.

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25 July 1945 (Continued)
1413 Sound contact, light screws bearing 240T. Came up for a look.
1417 Sighted small patrol vessel going up coast toward TODO SAKI. Con-
tinued patrolling along coast one mile off beach.
2013 Surfaced and opened coast to eastward. 148 mgs radar on TODO SAKI
steadied on us immediately and tracked us off and on all night. Used
SJ to seaward only. Searched along coast with SJ.

26 July 1945
Heading for 50 fathom curve off MIYAKO north of TODO SAKI. Had various
indications of SJ interference between 350T and 010T during night, but
investigation revealed nothing. Since weather has cleared have noted
some unusual ranges with SJ similar to conditions found here in May
in OKINAWA. It seems incredible though to believe this could be SEA
POACHER 100 miles north of us. Possible we have some reconnaissance
aircraft around.
0320 Submerged 8000 yards off HEI SAKI.
0400 Sighted small vessel bearing 333T and heard pinging in same direction.
Commenced approach on collision course. Initial range about 5000 yards.
Flooded tube #7.
0425 Fired tube #7.
0429 Heard small explosion. Screws stopped.
0432 Heard screws of two pingers to north of us. Headed toward.
0436 Heard pingers appeared to reverse course, so came around to close our
attack.
0447 At 62 feet. We have two pingers to north of us, one to the westward,
one to the southward.
0514 Sighted RUFE circling area at about 500 feet. There is no doubt in
our minds that they knew exactly where we dove. Sighted row boat with
3-4 Japs in the middle of a pile of wreckage. This vessel was about
75-100 tons, 100 feet long, had two masts and pilothouse.
0516 Sighted ship bearing 170T with zero angle on bow. Looked like he
might be worth a torpedo despite fact he seemed to be pinging. Came
to 90 track for stern shot. Subsequent observations showed he was too
small. He picked up the survivors and headed north.
0518 Headed down the coast to clear this spot. RUFE still circling area.
All A/S vessels have closed the beach and seem to be pinging away at
the rocks.

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26 July 1945 (Continued)
0820 Sighted five RUFE type planes in line of bearing being joined by a
     sixth flying south between us and the shore. These planes made several
     low sweeps over our general area. Went deep and headed East.
1200 Lat. 39-19 N, Long. 142-07 E.
1537 Heard 15 kcs pinging to northward.
1602 Sighted "Killer Group" of two SC's and one small CM. Decided CM would
     be best target for single stern shot. Commenced approach
1644 Target tracking on steady course 240T, speed 10 knots. Sound con-
     ditions good. Flooded #6 tube.
1646 No targets in sight. Sound lost contact. The sun shining thru the
     haze is completely blinding on the generated bearing of the target.
     Tried all filters and shallower depth, but neither C.O. nor Exec could
     see anything. Targets apparently were going into KAMAISHI for the
     night.
1712 Secured battle stations.
1751 Sighted five planes apparently bombers headed north.
2000 Surfaced.

27 July 1945
0008 Clear bright moonlight night. Radar on TODO SAKI steadies on us at
     intervals apparently checking our course and speed and then shuts off.
     Lookout reported sighting object on horizon in moon streak. Headed
     for on four engines.
0036 No results. Resumed course and speed.
0300 Submerged off TODO SAKI and headed south 2000 yards offshore.
0658 Heard pinging bearing 216T.
0741 Sound had screws bearing 207T. Went to battle stations. Sighted tar-
     get, identified as a 75 foot SUGAR DOG, probably a fisherman. Would
     have made a good gun target, but as it is still early in the day, and
     due to the heavy air patrols over us yesterday, decided not to surface.
     Secured from battle stations.
1200 Lat. 39-17 N, Long. 142-02 E.
1320 Sighted smoke bearing 203T. Went to battle stations submerged.
1322 Target identified as sea-going tug of estimated length 125 feet.
1334 ST range to target 4600 yards. Decided to fire torpedo aft because
     of length of target.
1337 Flooded tube #8. Target on course 020, speed 10, not zigzagging.

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28 July 1945 (Continued)
1354 Targets changed course to 020T to round ONE SAKI. Angle on bow 175S.
     Running at full speed between observations still wouldn't pull us up
     close enough for a shot.
     These vessels were characteristic of everything we have seen in these
     areas, small A/S vessels hugging the coast and ducking in and out of
     the bays and inlets. We have yet to see anything as much as
     4,000 yards off the beach or longer than 160 feet.
     Secured from battle stations.
1402 Sighted small vessel which looked like fisherman close to beach bear-
1620 ing 192T range about 6,000 yards. JT reported possible pinging on that
     bearing.
1629 Target is headed toward us with small starboard angle. A check out
     put us right on a 23 fathom spot with 50-60 fathoms in all directions
     around us. We didn't like to go below 100 feet with our sound dome
     extended for to pass ahead at about 300 yards with him in whites keep-
     ing a lookout on top of pilot house, and manning two machine guns on
     top of pilot house.
     He was about 75 feet long. Hoped he would be followed by a torpedo
     target.
1933 Surfaced and headed for lifeguard station.
2008 to Had APR, SJ, and ST indications of a friendly submarine bearing
2035 160T.
2115 Exchanged SJ recognition signals with ANGLER.
2245 Exchanged VHF signals with air cover.
2306 Commenced closing ANGLER. This is another example of the poor ranges
     we have been able to pick up radar signals in these areas.
2328 Lying to with ANGLER exchanging information.
2340 Decided to patrol KESSENUMA WAN tomorrow as POACHER won't be able
     to reach there from area ONE until dark.

29 July 1945
0300 Submerged 4,000 yards off O SHIMA at entrance to KESSENUM WAN.
     Sighted several small fishing boats during morning none greater than
     50 feet long.
1100 Visibility which had been good all morning is now reduced to about
     5,000 yards. Maintaining almost continuous periscope watch at 55 feet.
     Periscopes are run up and down often to clear fog off outer windows.
1200 Lat. 38-48 N. Long. 141-41 E.

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Subject: U.S.S. THORNDICK (SS418) - Report of First War Patrol.

29 July 1945 (Continued)
1330 Heard screw bearing 330T in direction of KESSENUMA WAN.
1335 Sighted ship bearing 330T. Got an ST range of 2,000 yards and went
     to battle stations. Can't tell whether angle on bow it's less or greater
     than 90. Commenced approach, tracking with ST range and periscope
     bearings.
1338 At range 3650 target passed out of sight on course 055T speed 9.
1350 Surfaced and commenced end around on 4 engines. Surface visibility
     about 1,000 yards and sun shining overhead. Picked target out of
     land pips, target now on course 020 speed 9. TODO SAKI radar at 148 mcs. steadied
     on us at saturation as soon as we surfaced and stayed right there. There
     will undoubtedly be a plane here soon. Target was tentatively identified, while he was
     in sight, as a steel sea truck similar to SANKO MARU page 77 of ONI
     208-J, Supplement 2. Decided to set all torpedoes on 5 feet.
     With range 5,500 yards, angle on bow 60 S and target tracking perfectly
     by TDC and two plots on a steady course of 028T speed 9, headed in to
     fire.
1420 Fired initial torpedo run of 2300 on an 85 starboard track gyro 60
     right commenced firing five bow tubes. Own speed 6 knots. Target still
     not in sight.
1426 Swung left to put target astern and await developments.
1428 Still no hits.
1430 Target had changed course to 270T. We tracked continually while the
     torpedoes were running and do not believe he zigged until about two
     minutes after torpedoes would have passed him. Torpedoes were spread
     90 feet apart at the target.
1431 Heard two explosions which we believe to be end of run explosions.
     Range to the beach at firing was about 5,500 yards.
1432 Target then changed course to 320T into bay. As we are well up into SEA
     area and target appears to be getting out of reach, swung
     around to south to clear area.
1435 Heard one felt heavy explosion which we believe to be a depth charge
     in direction of target. Target also firing many uns which sound
     similar to 20mm.
1437 Heard one on bridge heard plane in close overhead. Sky clear
     and the tracking data steady and in mutual agreement through
     out. No explanation for missing can be given. If this vessel was
     in the light condition he only drew 4.7 feet, but he looked loaded
     to us.
1444 Heard three more explosions.
1501 Surfaced and headed south toward area THREE. Took fifteen minutes to
     rig in bow planes. Bow planes have given increasing trouble the last
     few weeks, rigging in very slowly with much moaning and groaning.
1648 Investigation and lubrication have been of no help. It is believed.

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29 July 1945 (Continued)
that the rigging out arm is binding in the socket.
1710 Submerged when visibility increased enough for us to see beach.
1958 Surfaced and headed for SHIOYA SAKI.
2045 SJ interference - looks like friendly radar.
2052 Exchanged recognition signals with SEA POACHER on SJ.

30 July 1945
Flat calm sea, poor visibility.
0437 Submerged on 40 fathom curve northeast of SHIOYA SAKI headed west for
     20 fathom curve.
0734 Patrolling to southward along 20 fathom curve.
1200 Lat. 37-14 N. Long. 141-07 E.
1437 Due to a complete lack of any enemy activity at all, and very poor
     visibility decided to go back north of KINKASAN. Surfaced.
1450 Had APR contacts at 148 mcs, 77 mcs, 106 mcs and 153 mcs.
2208 SJ interference bearing 060T.
2209 Exchanged calls with SEA POACHER.
2300 Lying alongside SEA POACHER exchanging information and arranging
     gun shoot south of HOKKAIDO last night in area.
2330 Headed for KESENNUMA.

31 July 1945
0326 Submerged off O SHIMA in poor visibility. Ran to land 5,600 yards.
     Commenced patrolling parallel to beach.
1200 Lat. 38-33 N. Long. 141-35 E.
1420 Visibility rapidly getting worse, so decided to conduct surface
     patrol. Sky overhead perfectly clear. Heavy fog making up on the
     surface.
1434 Radar has possible contact close in to beach, but it could be rocks.
     Commenced tracking.
1452 Range 3000 yards. Can make out hazy outline. Looks like it could
     be good sized sea truck. Visibility shut down immediately. Decided
     to fire torpedoes on him.
1503 Fired tubes #6, #5, and #4 set on 3 foot 106 port track gyros 10 left,
     torpedo run 1600 yards. Swung left to parallel target.
1503-45 Fired two torpedoes hitting beach about 1000 yards other side of target.
1509 Target ship unchanged, so commenced closing target while going to
     surface stations.

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1 August 1945 (Continued)
1414 Slowed to 10 knots and opened fire on two large buildings at a range
     of 4,200 yards with 5" and 40mm round. The first five rounds were wild
     in range, but the gun crew quickly settle down and fired a small
     pattern for the remaining 100 rounds. After the 6th round the foot
     firing pointer broke off and the rest of the firing was by hand. A
     total of four targets were taken under fire; two of which were the
     factory and two at the power plant in URAKAMA. All targets were hit. On several
     occasions shells were seen to drop through the roof, exploding inside.
     There was no fire seen when we departed, but smoke was still visible astern.
     The firing took 22 minutes and was of inestimable value to the entire
     crew. The training was excellent and the boost to morale tremendous.
     Commenced clearing the area to the southeast on four engines.
1437 Commenced clearing the area to the southeast on four engines.
1502 Slowed to two engine speed.
1624 APR contact 323 mcs, PRF 400 (this is a new one to us).
1625 Keyed SD and had plane at 3 miles. Submerged
1800 Surfaced and set course for MIDWAY.

2 August 1945
     Enroute MIDWAY.

3 August 1945
     Bow planes were placed out of commission for remainder of patrol unless
     needed for an emergency.

4 August 1945
     Enroute MIDWAY.

5 August 1945
     Inspection of blower assembly on #2 main engine while carrying out
     progressive maintenance on this engine revealed blower lobes just
     touching. After investigation decided to renew thrust bearings at sea.

6-7 August 1945
     Enroute MIDWAY.

8 August 1945
0400 #2 Main Engine back in commission.
     Crossed International Date Line.

8 August 1945
     Arrived MIDWAY.

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(C) WEATHER

    The weather for this time of year north of SHIOYA SAKI to the
    southern shores of HOKKAIDO was just about as expected. There is a great
    deal of fog, and even on clear days the coast is very hazy and misty. The
    period from 10 July to 24 July was a succession of four straight storms fol-
    lowing one on top of the other. These are always characteristic of heavy
    seas from the southeast bringing heavy grey clouds and a falling barometer.
    About twelve hours after the barometer begins to rise the seas begin to flatten
    out and the wind slackens. The weather after 24 July was clear and invigorating
    with temperatures averaging about 65. Main injection temperatures in the areas
    averaged about 57 degrees.

(D) TIDAL INFORMATION

    Currents were as predicted in the pilots. Along the east coast of
    HONSHU the Oyashio was setting southward with an average drift of 1 knot. South-
    east of SHIRIYA SAKI the set was north in the morning, and south in the after-
    noon during the two days spent there.

(E) NAVIGATIONAL AIDS

    No navigational lights were seen to be burning. The entire coast
    is 100 per cent blacked out. The following lighthouses were sighted and showed
    no alterations: ERIMO SAKI, SHIRIYA SAKI, TODO SAKI, and URAKAWA. Peak navi-
    gation along the east coast of HONSHU and the south coast of HOKKAIDO is not
    good. Most of the peaks are of nearly the same height, and there are few that
    are distinctive. Tangents were much better.

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(G) AIRCRAFT CONTACTS

     The enemy aircraft activity was weak almost to the point of being
totally absent. The day we spent on the surface (11 July) east of KINKASAN
keying our SD brought them out very definitely in our direction. After
this we secured the SD and saw no more enemy planes on the surface. They
seemed to know where we had submerged the morning of 26 July, for six float
planes patrolled along the coast looking for us. It is believed the five
bombers seen in the afternoon were Army planes and were not on an ASW
mission. We feel that the plane covering our area southeast of SHIMIZU,
Saki on 23 July was making a definite effort to locate us and pin us
down while their submarine made its sortie after dark. It is rather likely
that the position of our morning dive was known.

     Twice while on the surface in very dense fog planes were heard very
loudly passing overhead. The second time was shortly after a torpedo
attack.

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(H) ATTACK DATA

U.S.S. THORNBACK TORPEDO ATTACK NO. 4 PATROL NO. 1

TIME: 1426(I) DATE: 29 July 1945 LAT: 38-48 N LONG: 141-41 E

DESCRIPTION: TARGET DATA - DAMAGE INFLICTED
First contact was made by JT sound gear at 1420 and five minutes
later the target was sighted by periscope while running
at 50 ft. at a range of 2000 yards. The target identified
as an unescorted sea truck similar to the SANKO MARU, page
77 of ONI 208-J Supplement No. 2, 950 tons. Visibility
was initially about 5000 yards, but suddenly dropped to
about 1500. The target was not zig-zagging and was not
sighted after surfacing.

SHIP SUNK: None.

SHIP DAMAGED BY: None.

TARGET DATA: 0 ft. COURSE: 028T SPEED: 9 kts. FIRING RANGE 2200 yds.
OWN SHIP DATA:
SPEED: 7.5 kts. COURSE: 280T DEPTH - Surfaced ANGLE - 0°

FIRE CONTROL & TORPEDO DATA

TYPE ATTACK:
Contact was made while submerged but the target was not
sighted until the angle on the bow was near 90 S. As the TDC
did not have a good solution before the target passed out of sight
at a range of 3650 yards it was decided to surface and conduct
an SJ radar approach in poor visibility. The target was tracked
up to and including the firing point using SJ radar ranges and
bearings exclusively as visibility was never greater than 1000
yards after surfacing. Plot and TDC were in mutual agreement
during the second phase of the approach and the entire fire con-
trol party was confident that it had an excellent solution.

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(H) ATTACK DATA (TORPEDO ATTACK NO. 4 Cont.)
REMARKS:
The torpedoes appeared to run normally. The target draft in
the fully loaded condition was 13 feet however in the light condition
it drew only 4.7 feet. It appeared that the target was loaded and with
the slight sea and swell, erratic depth control seems improbable. The
torpedoes were spread 90 feet at the target. Four end of run explosions
were heard.

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(H) ATTACK DATA (Continued)

TORPEDO ATTACK NO. 4 (Continued)
| #5 | #4 | #3 | #2 | #1
TUBES FIRED | | | | |
TRACK ANGLE | 84 S | 85 S | 85 S | 86 S | 86 S
GYRO ANGLE | 008 | 008 | 004 | 010 | 005
DEPTH SET | 5' | 5' | 5' | 5' | 5'
POWER | 27.9 | 27.9 | 27.9 | 27.9 | 27.9
HIT OR MISS | Miss | Miss | Miss | Miss | Miss
ERRATIC | No. | No | No | No | No
MARK TORPEDO | 18-2 | 18-2 | 18-2 | 18-2 | 18-2
SERIAL NO. | 57774 | 57520 | 55623 | 100823 | 56964
MARK EXPLODER | 8-5 | 8-7 | 8-7 | 8-5 | 8-7
SERIAL NO. | 9012 | 17181 | 17094 | 10456 | 17190
ACTUATION SET | - | - C O N T A C T | - | -
ACTUATION ACTUAL | - | - | - | - | -
MARK WARHEAD | 18-2 | 18-2 | 18-2 | 18-2 | 18-2
SERIAL NO. | 4784 | 6656 | 7191 | 6840 | 6755
EXPLOSIVE | TORPEX | TORPEX | TORPEX | TORPEX | TORPEX
FIRING INTERVAL | 0 | 8 | 8 | 8 | 8

TYPE SPREAD | D I V E R G E N T
SEA CONDITIONS | Smooth with slight swell
OVERHAUL ACTIVITY | Sub Base, Pearl Harbor, T. H.

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(H) ATTACK DATA (Continued)

U.S.S. THORNBACK TORPEDO ATTACK NO. 5 PATROL NO. 1

TIME: 1503(I) DATE: 31 July 1945 LAT. 38-53 N. LONG: 141-35 E.

TARGET DATA - DAMAGE INFLICTED

DESCRIPTION: The target was contacted on the surface in a dense fog
by SJ radar at an initial range of 5000 yards and was
sighted momentarily when the range closed to 3000 yards.
At that time it was considered that the ship was a satis-
factory torpedo target. In a gun engagement following
the torpedo attack the target was identified as a small
patrol vessel 100 feet long having a pilot house amidships,
two masts, radio antennae and one machine gun (HIS (EU)
100 tons).

SHIPS SUNK None

SHIPS DAMAGED None

DAMAGED DETERMINED BY:

TARGET DRAFT: 3 ft. COURSE 196T SPEED 7 kts. FIRING RANGE: 1630 yds.

OWN SHIP DATA

SPEED: 10 kts. COURSE: 285T DEPTH - Surfaced. ANGLE - 0°

FIRE CONTROL & TORPEDO DATA

TYPE ATTACK: The target was detected while searching with the SJ radar
at an opening range of about 5000 yards. Target was tracked using
SJ bearings and ranges exclusively. Commenced firing at a range
of 1630 yards, 15 left gyro angle and 106 T track.

REMARKS: During the approach when the range had closed to about 3000
yards, the visibility increased momentarily and the C.O. was able
to get a glimpse of the target. It appeared to be a small Sugar
Dog about 125 feet long. Simultaneously, SJ reported having a
strong pip. Poor visibility at the time ruled out a gun attack and
it was decided that the target was worth at least three torpedoes.

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C-O-N-F-I-D-E-N-T-I-A-L
Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(H) ATTACK DATA (Continued)

                       TORPEDO ATTACK NO. 5 (Continued)
                       #6         #5         #4
TUBES FIRED
TRACK ANGLE            106 P.     106 P      106 P
GYRO ANGLE             348        347.30     348
DEPTH SET              3          3
POWER                  27.73      27.73      27.73
HIT OR MISS            Miss       Miss       Miss
ERRATIC                No         No         No
MARK TORPEDO           18.2       18.2       18.2
SERIAL NO.             57148      57517      56997
MARK EXPLODER          8-5        8-7        8-5
SERIAL NO.             10139      15067      10368
ACTUATION SET          - - - - -  C O N T A C T  - - - - -
ACTUATION ACTUAL       18-2       18-2       18-2
SERIAL NO.             3683       5989       41-31
EXPLOSIVE              TORPEX     TORPEX     TORPEX
FIRING INTERVAL        0          8          8
TYPE SPREAD                       D I V E R G E N T
SEA CONDITIONS         1          1          1
OVERHAUL ACTIVITY S/M Base, P.H.  USS PROTEUS  S/M Base, P.H.

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Subject: U.S.S. THORNEACK (SS418) - Report of First War Patrol.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(I) MINES

A few mines were sighted south and southeast of HONSHU. We were un-
able to sink any with 20mm, 40mm, or .50 cal. The SEA POACHER reported
excellent results with two .30 cal. rifles. We intend to try out a couple
of these next patrol.

(J) ANTI-SUBMARINE MEASURES AND EVASION TACTICS

There were no new anti-submarine measures against this vessel. A
number of small pingers were contacted proceeding north or south close along
the shore. There seemed to be no organized searching except possibly the
morning of 26 July. On this date several A/S vessels and planes were con-
centrated in a small area, but they were no hazard. No contacts were made
on this vessel although on several occasions we were close aboard vessels
which had apparently stopped pinging for a few minutes in order to listen.
We made it a standard operating policy on all day dives to operate planes
and steering in emergency. This is equally easy of operation and much
quieter than power. Specifically, in these areas it can be said that A/S
measures were ineffective. All anti-submarine vessels carried small machine
guns, and the two A/S had at least two either two or three inch guns.

(K) HULL & MACHINERY - MAJOR DEFECTS & DAMAGES

#3 Main Engine Blower: After getting underway on 26 June 1945 from GUAM for
SAIPAN, as soon as full speed was rung up a knock was heard at the blower
end of #3 Main Engine. The engine was immediately secured and inspection
revealed scoring of the blower lobes. Clearances were taken and timing
checked after engine had cooled. Since all readings were within prescribed
limits, it was assumed that trouble was caused by foreign matter getting
into the blower. End plate was removed, lobes were stoned smooth, outer
bearings renewed, and blower reassembled. Although clearances were again
correct, after 1 hour of running noise developed as before. Clearances
after cooling were again correct. An entire new matched lobo assembly
with timing gears was installed and inner impeller shaft bearings were re-
newed. Upon reassembly no more difficulty was encountered during the patrol.

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C-O-N-F-I-D-E-N-T-I-A-L
Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(K) HULL & MACHINERY - MAJOR DEFECTS & DAMAGES (CONTINUED)

#3 Main Engine Blower (Cont'd): This casualty delayed the ship's departure
from SAIPAN from 27 June to 30 June. The cause was never certainly de-
termined. Measurement revealed that the upper outer impeller shaft roller
bearing race was 0.010" thicker from face to face than the standard for
those bearings. It is considered most probable that wearing of the impeller
shaft drive caused the casualty. All work was done by ship's force.
The casualty developed after 1026 engine hours.

Bow Planes: As the patrol progressed, increased difficulty was encountered
in rigging in in the bow planes. Bow planes were ordinarily rigged in on 12
or 14 degrees dive. By July 9th it was noted that planes seemed slow
in rigging in, and the rubbing of both connecting rods was rubbing against
the bearing cap. The slowness of the motor was noticeably by some increase of load. On July 10th the gear
casing outside the pressure hull was inspected. It was found to be flooded.
It was drained and refilled and the packing glands tightened. At this time
also it was noted that the after sides of the sockets on the upper ball and
socket joints of both connecting rods was rubbing against the bearing cap.
The slowness of rigging in grew worse from day to day and the rubbing became
harder. Experiment proved that the rubbing was reduced and better results
were obtained by rigging in on 8 degrees dive. After July 12th this practice
was followed. The rubbing again began to become more severe it was
found necessary on July 30th to rig in with the planes on zero. On August
1st the gear casing was again found to be flooded and was again refilled;
packing glands appeared tight. No trace of metal was ever found when
draining gear casing. Refilling gear casing caused no noticeable improvement
in operation. Conditions continued to be aggravated and on August 3rd it
was decided to avoid all dives except as essential to the ship's safety.
The cause of the trouble has not been determined and a thorough overhaul
and checking of the bow planes will be necessary during the coming refit
period.

Bendix Log: While enroute from PEARL HARBOR to GUAM the miles run indicator
of the Bendix Log read consistently high. Upon inspection it was found that
the fiber gear in the gear and worn speed reduction unit in the frame of the
Bodine Driving Motor was excessively worn. This gear drives the constant
speed disc of the integrating mechanism of the Master Transmitter indicator
unit. The entire Bodine synchronous motor assembly was replaced by a spare
and the Bendix Log gave excellent performance for the remainder of the patrol.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(K) HULL & MACHINERY - MAJOR DEFECTS & DAMAGES (CONTINUED)

Bendix Log (Cont'd): Since this motor assembly had previously been renewed
for the same reason in February it seems probable that the design of this
speed reduction gear train is faulty.

Periscopes: Both periscopes leaked excessively during the patrol. The
packing is Garlock chevron packing. For a while after commissioning, we
were very proud of our periscopes. They did not leak, were free of dirt
and exceptionally easy to train. Although they are still perfectly dry at
300 feet, leakage at periscope depth has become progressively worse. There
is little or no evidence of dirt in the bearings. An attempt was made to
install a ring of flax packing under the Garlock, but this was not possible
as the gland would not pull up tight enough to permit replacing the TBT.
Drip pans were installed over the eyepieces which permitted the observer to
remain partially dry.
Both periscopes are too noisy at the start and stop of a raising or
lowering operation. The cause seems largely due to the difficulty of
operating the control valves smoothly. Considerable improvement was affected
on #2 periscope by adding an extension to the control handle. The increased
leverage permitted smoother control. However, some of the trouble, part-
icularly on #1 periscope, is probably due to defects in the control valves,
as hydraulic oil in vent and return lines was slightly contaminated during
commissioning training.
The periscopes are very unsatisfactory in their present condition and
a definite improvement both in hoisting and tightness must be effected
during refit.

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Subject: U.S.S. THORNBACK (SS/18) - Report of First War Patrol.

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Subject: U.S.S. THORNBACK (SS416) - Report of First War Patrol.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(K) ORDNANCE & GUNNERY - MAJOR DEFECTS

1. During the shore bombardment of 1 August, the foot firing mechanism of
the 5"/25 failed, necessitating firing by hand. This failure was due to
rupture of the trigger push rod (Dr. No. 256907-2) at the threads below the
nut which locks the adjustable push rod end. It has been determined that
rupture resulted from fatigue failure, caused by a repeated transverse
stress being placed on the push rod when it is forced against the trigger
by the action of the upper bellows. This is the second failure that this
piece has experienced in the past six months. It is recommended that a
stronger material than naval brass, which is specified, be used in manu-
facturing a replacement and spares.

2. While ventilating Mk. 18 Mod. 2 torpedo #57148, five battery compartment
handhole plates lifted from their seats. The ventilating air was immediately
secured and upon investigation a kink in the ventilating air discharge line
in the afterbody was discovered. This caused a pressure to be built up in
the battery compartment which was relieved by the lifting of the handhole
plates. All spiders were distorted and two were damaged beyond repair.
The damaged spiders were replaced and the others were bent into their original
shape. With the renewed and repaired spiders and handholes in place, a
5# pressure test was applied to the battery compartment. Satisfactory
results were obtained and no further trouble was experienced with this
torpedo. Overhaul activity was Subase, Pearl Harbor, T. H.

3. During the first freshening charge of Mk. 18 Mod. 2 torpedo #56974 on
15 June 1945, a double voltage reading of 16.2 volts between cells #4 and
#6 was obtained while a negative reading of 8.1 volts between cells #6 and
#12 was observed. Investigation revealed that the leads from the negative
terminal of cell #12 and the positive terminal of cell #6 were reversed in
the terminal block. The defect was not remedied but during subsequent
charges the readings shown above were accepted as normal.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(L) RADIO
RADIO MATERIAL TROUBLES

VHF--7/12/45
The VHF receiver failed when the unit lost high voltage. The relay coil
and Item 296 choke and transformer windings were found open. Having no
spares other than tubes, repairs were attempted from other equipment parts
but proper sensitivity could not be obtained. The T2/AMR-1 was used as a
receiver for the remainder of the patrol.

SCR 610--7/16/45
Lack of spares for the SCR 610 also proved aggravating when excessive voltage
burned out all the tube filaments. With only one set of tubes as spares,
the set was put in operation with a dry cell battery supplying the filament
voltage. This was done to prevent the possible recurrence of this casualty
and complete loss of the equipment.

When attempting to obtain spares for the VHF and SCR 610 at Pearl we were
informed that our technicians were only expected to test tubes. If anything
else went out our best bet would be to secure the set until reaching port.
ComSubFac has told submarines to guard 140.58 mcs. continuously but still
no spares.

TBL-12 -- 7/31/45
The TBL went out due to loss of high voltage. Fuse (F451) was replaced in
high voltage generator and operation was normal.

The antenna inductance tuning control gave trouble on several occasions.
When turned back to zero the control rides past the stop and off the track
causing much lost time while transmitter is pulled out to replace this
control.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(14) RADAR
SD-5:
The SD was a very reliable piece of gear. It was kept in the standby
position at all times. In areas where friendly planes were expected, the
SD was keyed for 1 or 2 seconds out of every 3 minutes. This system worked
very well and on only two occasions did planes get within 6 miles without
being previously detected. Luckily both of these planes were friendly.
When in areas where friendly planes were not expected, the SD was keyed for
a period of 1 second when AIR contacts indicated the possible presence of
planes. Maximum ranges were 30 miles to land and 40 to planes. A list of
material casualties follows:

6/24 Receiver scope blank. Changed defective C.R.T. (2AP1). Operation
normal. No operation time lost; in port.
6/25 "A" scope blank. Found shorted capacitor (C946) in rectifier. Re-
placed capacitor. Operation normal. No operation time lost; in port.
8/4 Improper focus on "A" scope followed by blanking of "A" scope. Found
H.V. rectifier tube (2X2) arcing, resistor (R241) burned out and open,
and capacitor (C930) leaking. Believe defective capacitor (C930) to
be cause of failure. Replaced defective parts. Operation normal.
6 hours operation time lost.

SJ-1:
The performance of the SJ-1 radar during this patrol was considered
excellent. Few material difficulties occurred and those that did required very
little time to correct. On several occasions ran on to land as far as
150,000 yards were obtained and twice radar tracking stations were manned
only to find that the targets were second sweep echoes from land. During
heavy fogs, two radar surface approaches were made on targets within 2000
yards of the beach at contact ranges of 7000 yards. The radar tracking was
considered very good.
The first few days in the areas it was noticed that when the SJ was
used toward the beach, shorebased radars immediately came on and apparently
made very thorough searches in our direction. Sweeping radars steadied on
us and keyed radars came on. After this condition was found to exist, the
SJ was only used for sweeps away from land and the ST toward, except at
times when the SJ was used to track targets previously discovered.

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SS413/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS413) - Report of First War Patrol.

(M) RADAR (CONTINUED)

SJ-1 (Cont'd):

Some sample contact ranges obtained during this patrol were as follows:

                                                Min.        Max.
        Naval Patrol and Fishing Vessels        6000        8000
        Submarines                              9000        18000
        Small Surface Craft                     6000

        All contacts made with friendly submarines were preceded by the inter-
ception of interference on the other submarine's beam. Some of the
ranges of interception were phenomenal, and subsequent identification and
communication were carried out with surprising ease.
        A list of material casualties follows:

6/21    Arcing in antenna training motor switching box. Filed and cleaned
        contacts. Operation improved but below normal because of pitted con-
        tacts. No operation time lost; in port.
6/24    Lost high voltage rectifier current. Found retarded coil in bias regu-
        lator circuit (L1) open. Replaced coil, operation returned to normal.
        No operation time lost; in port.
6/24    Arcing in antenna training motor switching box. Replaced all contacts
        and honed to fit. Operation normal. No operation time lost; in port.
6/25    Loss of sensitivity. Retuned and changed R.F. coaxial connections.
        Sensitivity doubled with respect to ping time. No operation time lost;
        in port.
6/25    A.F.C. circuit inoperative. Replaced all tubes in A.F.C. circuit.
        Operation normal. No operation time lost; in port.
6/25    High Voltage Rectifier output below normal. Replaced two 5U4G's with
        5R4G's. Operation normal. No operation time lost; in port.
8/1     Loss of echoes. Replaced magnetron ('706AY), replaced T.R. tube (721A),
        replaced two I.F. tubes (717A), and changed crystal. Operation normal.
        4 hours operation time lost.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(M) RADAR (CONTINUED)

ST Periscope Radar:

          The principal advantage of the ST radar is that the Japs apparently
cannot detect its presence. Because of this fact, it was used for sweeping
practically all the time in the area. However, the disadvantage of such a
wide beam width made it almost useless because of the proximity of the
beach. Unless the target was nearly directly between the
submarine and the beach, it was almost impossible to determine or even see
the target echoes in the maze of land echoes. The equipment was used for
tracking only once and results were satisfactory.
          On one occasion, after searching with the SJ very thoroughly on the
bearing of SJ interference, with no echo, we shifted to ST and immediately
picked up a friendly submarine at 9600 yards. The SJ was found to be out
of tune.
          Before leaving PEARL HARBOR, an arrangement was made whereby the bearing
information from the ST periscope to the TDC was also sent to a selsyn motor
attached to the TPI train. This made possible TPI presentation of ST
targets. However, the wide beam width of this radar made this attachment
useless when in close to land. Away from interfering land echoes, bearings
of from 2 to 3 degrees accuracy could be obtained by halving the echo on
the PPI.
          A list of material casualties follows:

6/25 Low sensitivity. Changed crystal (IN23) and returned. Operation normal.
     No operation time lost; in port.
7/28 Low sensitivity. Changed crystal (IN23). Operation improved but
     below normal. 10 minutes operation time lost.
7/28 Loss of echoes. No keep alive voltage. Found open lead in cable (P4).
     Repaired cable, changed crystal, T.R. tube (724B) and three I.F. tubes
     (6AK5's). Conditions normal. 2 hours operation time lost.
7/30 Antenna switching unit failed. Found switch (SPDT-S3) operating im-
     properly. Replaced switch. Conditions normal. No operation time lost.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(M) RADAR (CONTINUED)
AN/APR-1 - APR-5AX - AN/SPA-1

After the replacement of the TN3 tuning head in SAIPAN, the entire APR-1
assembly was extremely reliable. However, the directions ANTONA called
for what proved to be a poor piece of workmanship. The adjusting arm and center
shaft were made of such poor materials that the setscrew connection between
these two parts was completely stripped. This difficulty was easily and
effectively eliminated by inverting the box, removing the bottom cover plate,
bracing the center shaft and from that time on, moving the contact arms by
hand.

The APR-5 was an almost complete failure. The coupling capacitor (C111)
in unit T102 began leaking and it was necessary to replace it with a cap-
acitor from the spares for other equipment. After this time the APR-5 was
very unreliable. It is recommended that a more complete set of spare parts
be furnished with this piece of equipment.
Little difficulty was experienced with the SPA-1. The only casualty
occurred when capacitor C136 was found leaking. After replacing this
capacitor, no other trouble was encountered.

(N) SONAR GEAR AND SOUND CONDITIONS:

The sound conditions in the areas were considered fair. It is reason-
able to believe that this submarine was never detected by the sound gear of
the Japanese. On one occasion a patrol boat came around a point of land
about 4000 yards away and made a Jap's idea of a thorough search of the area
ahead, secured his gear and then passed us at a range of about 400 yards.
The operators were undoubtedly third rate and have been used to pick up
lack of actual targets in the past.
It is difficult to discuss the relative merits of our own sonic and
supersonic sound installations. (We have one of the first two JT install-
ations). Finback was picked up at ranges from 6000 to 3000 yards and the
screws of the small targets encountered were detected at ranges from 3000
to 5000 yards. Most of the shipping along this particular stretch of coast-
line hugs the beach so closely that the sonic and supersonic sound gear
usually picked up the target at approximately the same time. This was when
the targets came around a point of land.

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Subject: U.S.S. THORNBACK (SS416) - Report of First War Patrol.

(N) SONAR GEAR AND SOUND CONDITIONS (CONT'D)

TDM (Cont'd)

A list of material failures follows:

6/13 Micro switch failed. Replaced with spare. Operation normal. Five
     minutes operation time lost.
6/14 Micro switch failed. Replaced spring in switch. Operation normal.
     minutes operation time lost.
6/14 Same.
6/15 Same.
6/16 Same.
6/16 Same.
6/18 Same.
6/19 Same.
6/20 Slip ring parted. Replaced slip ring. Operation normal.
6/25 Same as 6/14.
7/1 Same as 6/20.
7/2 Rotation of starboard sound head slowing. Reseated brushes and changed
     grease in QB training motor generator and training motor. This con-
     dition was not improved, head is still training slow unless an increase
     in voltage is applied. No operation time lost.
7/3 QB shaft found to be scored by bearing. Smoothed with slip stone.
     Operation normal. No operation time lost.
7/13 Pulley cord on chemical recorder parted. Replaced cord. Operation
     normal. 15 minutes operation time lost.
7/14 Stylus on chemical recorder inoperative. Replaced stylus. Operation
     normal. 5 minutes operation time lost.
7/16 Stylus carriage on chemical recorder inoperative. Replaced carriage.
     Operation normal. No operation time lost.
7/21 QB out of commission. Found varistor (VL11) burned out. Replaced
     varistor. Operation normal. 30 minutes operation time lost.
7/29 QB out of commission. Intermittent open in voltage amplifier (6C6-
     V101). Replaced tube. Operation normal. 20 minutes operation time
     lost.
8/4 Chemical recorder out of commission. The upper piece of the magnetic
     clutch shaft found fractured. Replaced fractured shaft with new
     shaft. (It was necessary to turn out the new shaft on the ship's
     lathe). Operation normal. 15 hours operation time lost.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(O) DENSITY LAYERS

     Outside the 100 fathom curve where the patrol was conducted until
July 21st, density layers were encountered on all but one dive (when iso
ballast conditions prevailed). Between latitude 33°N and 42°N negative
gradients were encountered with layer depths from 20 to 95 feet. These
extended down to depths of 185 feet. The temperature change in the gradi-
ents ranged from 2 to 14½ degrees. A typical card for this area in this
season would have isothermal water to 65 feet, a 7° thermocline between 65
and 150 feet followed by iso-ballast conditions to at least 200 feet. Very
few dives below 200 feet were made by this vessel. On one occasion a small
thermocline was encountered at 250 feet. While outside the 100 fathom curve,
H.O. 210 Submarine Supplement to Sailing Directions, Japanese Empire Area
was found to be accurate and valuable.
     After July 21st many cards were taken inside the 100 fathom curve, 2 to
5 miles offshore. East of ERIMO SAKI (HOKKAIDO) extreme gradients were
encountered (38-10N and 142-00E on the two dives made) between 45 and 140 feet.
Southeast of SHIRIYA SAKI (HONSHU) there were no thermoclines.
     East and south of KAMAISHI conditions were variable. Moderate thermo-
clines existed, starting at 40-60 feet. There were often several small
gradients above 200 feet. Around O SHIMA (38-31N) thermoclines began above
40 feet. Extreme variations were found at constant depth without much
affect on trim. Four degree changes in 10 minutes at the same depth were
not unusual. In OFFA WAN off the mouth of OFFA KAWA a small positive
gradient with currents affecting steering and indications of a salinity
gradient was found.

(P) HEALTH, FOOD, AND HABITABILITY

     Health was excellent throughout the entire patrol, and there was almost
a complete absence of colds. The quality of the food supplied is excellent.
Variety is still a hard thing to maintain over such an extended period.
The baker's products were the delight of all and the highlight of the
Commissary Department. Habitability was most satisfactory except in the
forward battery and forward torpedo room. In warm waters we cannot get the
temperature in the forward battery below 80, despite the fact that we have
the McQuade type coils and 10 h.p. motors. A booster blower and additional
coil are most desirable.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(P) HEALTH, FOOD, AND HABITABILITY (CONT'D)

The books issued for this patrol must be rated "Poor" in readability.
The Armed Forces editions contain a surprisingly large number of volumes
which interested no one. Next time we'll pick our own titles.

Movies are great for morale and certainly appreciated. We swapped
movies every chance we could get, and before the patrol was over we man-
aged to show eighteen different programs at sea.

The transcription records are excellent and relegate to a back seat
the static filled short wave broadcasts.

(Q) PERSONNEL

(a) Number of men detached after previous patrol0
(b) Number of men on board during patrol82
(c) Number of men qualified at start of patrol46
(d) Number of men qualified at end of patrol71
(e) Number of unqualified men making first patrol36

The performance of officers and men has been most satisfactory. The
type of men being supplied from Submarine School seems to have greatly im-
proved in quality since the beginning of the war. The men, though young,
are alert, interested, enthusiastic, and clean cut. There is not a single
man in the crew who has displayed any nervousness or tension at any time
during the patrol. Acey-Duecy and Cribbage Leagues were organized to keep
up morale and competitive spirit. We use a point system for grading our
lookouts, weighting various objects according to their importance. The
finest lookout of the patrol wins a war bond.

We made it a point before reaching PEARL to eliminate any man who could
not get along with his shipmates. It has worked out well. In each case
the replacement was a better man professionally as well as in personality.

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Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(T) FACTORS OF ENDURANCE REMAINING

TORPEDOES             FUEL                 PROVISIONS           PERSONNEL FACTOR

14 Mk. 18             8,000 gallons        15 days              10 days
1 Mk. 27
1 Mk. 28

Limiting factor this patrol.......PATROL ORDERS.......

(U) COMMUNICATIONS, RADAR, AND SONAR COUNTERMEASURES

RADAR COUNTERMEASURES

(1) Intercept of enemy signals: The entire offshore area of HONSHU between
SHIRIYA SAKI and SHIOYA SAKI seemed to be very well covered by enemy shore-
based radar installations. Whenever we surfaced it was only a matter of
seconds before a strong contact was made on the APR. Nearly all the con-
tacts were between 100 and 150 mcs. Bearings of some of these installations
were taken using the directional antenna system. Their approximate locations
and characteristics were as follows:

| | FREQ. | PRF | PULSE WIDTH |
| :| :---- | :-- | :|
| TORI' SAKI        | 147   | 450 | 8 - 10      |
| INUDO SAKI        | 145   | 400 | 8 - 10      |
| KINKASAN          | 150   | 400 | 10          |
| RYORI SAKI        | 148   | 450 | 15          |
| SHIRIYA SAKI      | 100   | 450 | 10          |

Other contacts of interest selected from the APR log are as follows:

| DATE | TIME(I) | LAT.(N) | LONG.(E) | FREQ. | PULSE RATE | PULSE WIDTH | REMARKS                                |
| :--- | :------ | :------ | :------- | :---- | :| :| :|
| 7/2  | 1130    | 22-30   | 139-55   | 99    | 425        | 20          | Off 1 min. 40 sec. On weak             |
|      |         |         |          |       |            |             | for 1 min. reaching max. at            |
|      |         |         |          |       |            |             | 1 min. 40 sec.                         |
| 7/2  | 1508    | 23-12   | 139-55   | 209   | 300        |             | Sweeps 20 sec.                         |
| 7/2  | 1545    | 23-15   | 139-55   | 202   |            | 6           | Slow sweeping radar.                   |

- 54 -

— page 66 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(U) COMMUNICATIONS, RADAR, AND SONAR COUNTERMEASURES (CONTINUED)
| DATE | TIME(I) | LAT.(N) | LONG.(E) | FREQ. | PULSE RATE | PULSE WIDTH | REMARKS |
|---|---|---|---|---|---|---|---|
| 7/3 | 1530 | 27-40 | 139-32 | 200 | 60 | 8 | Steady (tin can). |
| 7/3 | 1500 | 27-46 | 139-32 | 200 | 60 | 8 | Sweeping 2 RPM (AL. Destroyer) |
| 7/4 | 0235 | 29-39 | 139-32 | 200 | 60 | | Weak. About 1 sec. every 3 |
| | | | | | | | or 4 min. |
| 7/4 | 2015 | 30-25 | 139-50 | 147 | 500 | 12 | Steady, then off. |
| 7/4 | 2115 | 30-40 | 140-00 | 141 | 500 | 3 | Contact seems trained on us. |
| 7/5 | 1550 | 29-18 | 143-26 | 108 | 250 | 25 | Sweeping slow. |
| 7/7 | 1140 | 29-40 | 146-37 | 79 | 400 | 12 | On constantly. |
| 7/7 | 1245 | 29-40 | 146-37 | 74 | 500 | 30 | Steady. |
| 7/10 | 1645 | 31-25 | 142-45 | 178 | 150 | 8-10 | Weak - steady. |
| 7/10 | 1715 | 31-33 | 142-22 | 150 | 400 | 10 | Sweeping. |
| 7/11 | 0120 | 37-45 | 142-00 | 150 | 400 | 10 | Strong slow sweeping. Est. |
| | | | | | | | 320 T. |
| 7/11 | 0145 | 37-45 | 141-43 | 102 | 480 | 25 | Strong. Steady. |
| 7/11 | 0200 | 37-45 | 141-44 | 192 | 900 | 14 | Slow sweeps. |
| 7/11 | 0215 | 37-45 | 141-51 | 192 | 1000 | 13 | Steady. Strong. |
| 7/14 | 0130 | 37-30 | 141-43 | 94 | 475 | 25 | Strong. Steady on us. |
| 7/15 | 2000 | 38-30 | 140-55 | 192 | 60 | 6 | Keyed 2 sec. every 30 sec. |
| | | | | | | | Moderate contact. |
| 7/16 | 0527 | 37-30 | 145-35 | 1450 | 1700 | | Slow sweeping. |
| 7/19 | 0710 | 37-10 | 141-07 | 148 | 400 | 8 | Sweeping slow. |
| 7/19 | 1010 | 38-10 | 140-53 | 104 | 350 | 22 | Slow sweeping. |
| 7/19 | 1715 | 38-10 | 140-58 | 100 | 400 | 60 | Slow sweeping. Landbased. |
| 7.19 | 1732 | 38-10 | 141-00 | 92 | 750 | 60 | Slow sweeping. |
| 7/19 | 2030 | 38-15 | 141-15 | 145 | 400 | 27 | Saturation. On us 45 sec. |
| | | | | | | | off about 1 min. Appears to |
| | | | | | | | be sweeping very slow. |
| 7/22 | 0445 | 40-15 | 141-03 | 100 | 400 | 10 | Slow sweeping. Weak. |
| 7/22 | 2359 | 40-07.7 | 140-50 | 100 | 400 | 10 | Slow sweeping. Strong |
| | | | | | | | about 10 sec. SHIRIYA SAKI. |
| 7/24 | 1900 | 41-06 | 140-59 | 100 | 400 | 10 | Steady. |
| 7/25 | 1150 | 39-37.6 | 140-35.9 | 100 | 400 | 10-15 | Very weak. |
| 7/26 | 2325 | 39-27.0 | 140-27.0 | 100 | 400 | 24 | Fast sweeping. |
| 7/27 | 2010 | 39-08.0 | 142-02.1 | 150 | 500 | 24 | Strong slow sweeping. |
| 7/27 | 2040 | 39-08.0 | 142-10.2 | 159 | 475 | 9 | Weak. Steady. |

— page 67 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(U) COMMUNICATIONS, RADAR, AND SONAR COUNTERMEASURES (CONTINUED)

| DATE | TIME(I) | LAT.(N) | LONG.(E) | FREQ. | PULSE RATE | PULSE WIDTH | REMARKS |
|---|---|---|---|---|---|---|---|
| 7/28 | 2035 | 38-45.2 | 141-50 | 108 | 300 | 30 | Steady. |
| 7/30 | 0418 | 37-25 | 141-13.7 | 108 | 350 | 35 | Very strong. Slow sweeping. |
| 7/30 | 2219 | 38-55 | 141-50 | 156 | 400 | 10 | Looked like the radar was |
| | | | | | | | trying to send code of some |
| | | | | | | | sort, but was unintelligible. |
| 7/31 | 1839 | 38-45 | 141-43.5 | 198 | 400 | | Sweeping. Weak. |
| 8/2 | 0012 | 43 | 142-50 | 150 | 350 | 17 | Sweeping. Weak. |

(2) Jamming, own and enemy: None attempted or observed.

(3) Deception, own and enemy: The SJ was not used toward land unless
special circumstances warranted it or unless the range to land was over
25,000 yards. In areas where friendly planes were not ex-
pected, the SD was keyed for a 1 second duration at times when AFR contacts
indicated the possible presence of planes.

(4) Scope of photographs of targets of interest or unusual phenomena.

No radar reflectors were noticed to be rigged either on land or the patrol
boats encountered.

RADIO COUNTERMEASURES

(1) Enemy signals sent on SAFPLAN frequencies repeated
by undistinguishable characters. This occurred all the time
while in area. They could usually be tuned out but at times made our signals
unreadable.

(2) Definite enemy jamming encountered on SAFPLAN frequency 31 July when
transmitting to the ANGLER. About six enemy stations opened up with CW
signals trying to drown out the ANGLER'S receipt. Though aggravating, this
jamming did not prevent communications.
While transmitting to GUAM on 9 July a small amount of CW and bagpipe
jamming occurred on 8470 kcs.
On 4155 kcs NPM "J" FOX interfered with loud signals making it im-
possible at times to hear other signals. This signal was present at all
times.

- 56 -

— page 68 —
SS418/A16-3
Serial (032)
C-O-N-F-I-D-E-N-T-I-A-L
Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(II) COMMUNICATIONS, RADAR, AND SONAR COUNTERMEASURES (CONTINUED)
    RADIO COUNTERMEASURES (CONT'D)
        (3) On 24 July a station calling itself NPM on 4235 kcs asked us for a
            series of V's but would not authenticate. He again asked for V's but would
            not authenticate. His signal was stronger than either NPN or NPH has ever
            been in area.

    SONAR COUNTERMEASURES
        Very few enemy echo ranging equipped vessels were encountered, with the
        exception of one. All heard used a frequency between 15.5 and 16.2 kcs.
        On one occasion the sound operator reported possible pinging on 14.9 kcs.

(V) REMARKS
    During this patrol the first day or two spent in an area was intention-
    ally devoted to looking for suitable torpedo targets and two or three
    possible gun targets were passed up in hopes that something bigger would
    come along. In nearly every instance the small as well as the larger targets
    sighted were in position to get clear in short order merely by heading into
    one of the many bays and inlets in the immediate vicinity.
        The opinion of all the experienced personnel of this ship is that in the
    year they have been away from submarine warfare there has been an astounding
    change in the resistance and countermeasures of our enemy. The four weeks
    spent in operating areas along the east coast of HONSHU and southern coast
    of HOKKAIDO revealed that no ships either large or small came out more than
    3000 yards from the coast. Planes also (what few there were) stay very
    close to the coast. No vessels over 165' long were contacted. It is
    believed that any traffic through these areas must proceed either in fog or
    at night. However, it may be that following the Third Fleet's week in these
    areas there is no more shipping. It is felt that with the great change in
    enemy resistance and the character and size of the shipping that remains
    that we could be much more effective if we had two 5" guns, plus a rocket
    launcher and a flame thrower. We would like to carry fewer torpedoes and
    much more ammunition. The only way to effectively patrol these areas is by
    close patrol day and night, engaging by gunfire all targets within range
    unless certain they are of a size suitable for torpedoes. The increased use
    of Mk 27 and Mk 28 torpedoes is recommended.

- 57 -

— page 69 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(V) REMARKS (CONTINUED)
     We are very proud of our 417 class submarine, and we think this class
is the finest diving submarine in the world. Our average diving time from
"Clear the Bridge" to 50 feet is 38 seconds. By the recommendation of the
Portsmouth Navy Yard we pull the one half hour rate on the battery on the
sounding of the diving alarm. This cuts about 5 seconds off the diving
time obtained when using the one hour rate. The drain on the batteries is
negligible.
     The variable fuel oil tanks have been found a great aid. The difference
between a fully loaded fuel condition and a no fuel condition is 17,000
pounds, and this feature allows any trim variations as a result of fuel
changes to be easily accomplished in the variable ballast tanks.
     Our chief complaint on this class is that although we have the McQuade
type coils and the 10 h.p. motors it is impossible to bring the forward
battery temperature below 88 degrees when in warm water. This is partly
due to battery temperature and partly to inadequacy of ventilation and
cooling. The maneuvering room, however, is very comfortable. The plants
have removed enough moisture from the air to allow extensive use of the
washing machine every day. Both plants have been operated continuously
since leaving PEARL and since leaving SAIPAN only two electrical grounds
have occurred - both minor.
     We consider the performance of our lookouts exceptionally outstanding.
We follow the procedure given them in lookout training as regards procedure
and reports with only one or two modifications, and find it most satis-
factory. One modification which helps both OOD and lookout is to report
either "starboard" or "port" followed by the number of degrees from 0-180.
It was extremely rare for the OOD to see something before the lookout. In
years gone by this always was an exception to the rule. Constant harping on
the phraseology of lookouts and radar operators has paid great dividends.
Reports have been speeded up and simplified by cutting them to the minimum
number of words necessary for perfect clarity, and making them stereotyped.
It is now rare when someone misunderstands either an order or a report.
At first there was some confusion when the OOD on the FMC called SJ, ST,
or SD. By changing the name of the conning tower radar operator to "Radar
One" and control room operator to "Radar Two" we eliminated this.

- 58 -

— page 70 —
SS418/A16-3
Serial (032)

C-O-N-F-I-D-E-N-T-I-A-L

Subject: U.S.S. THORNBACK (SS418) - Report of First War Patrol.

(V) REMARKS (CONTINUED)

     The experimental 1MC-7MC system installed on this vessel has proven
most satisfactory. This system includes outlets to both torpedo rooms,
maneuvering control, control radar, bridge (forward and aft) and conning
tower (if in conning tower positioned for helmsman, radar & TDM operator,
TDC, and nest. Approach. Stations on the line can be switched in or out
at the control panel by means of toggle switches. Calls can be made
either "Hot Mic" or "Press to talk". This system is free from feed back and is
extremely rugged and reliable. The bridge speakers are effective in strong
winds. It is recommended that a two station system from OOD to radio room
be installed.
     We'd like to express our appreciation for the cooperation and outstand-
ing training afforded by ComSubRon THREE in the PANAMA area.
     It is suggested that increased emphasis be placed on gunnery training
and developments. We would like to conduct a battle surface firing daily
during the training period.

- 59 -

— page 71 —
SUBMARINE DIVISION THREE TWENTY-ONE

FB5-321/A16-3                                      Care of Fleet Post Office,
Serial: (087)                                      San Francisco, California,
                                                   10 August 1945.
C-O-N-F-I-D-E-N-T-I-A-L

FIRST ENDORSEMENT to
USS THORNBACK (SS418)
Conf. ltr. A16-3 over
Serial (032) dated
8 August 1945.

From:      The Commander Submarine Division THREE TWENTY-ONE.
To :       The Commander-in-Chief, United States Fleet.
Via :      (1) The Commander Submarine Squadron THIRTY-TWO.
           (2) The Commander Submarine Force, U.S. Pacific.
           (3) The Commander-in-Chief, U.S. Pacific Fleet.

Subject:   U.S.S. THORNBACK (SS418) - Report of FIRST War Patrol.

           1. The first war patrol of the U.S.S. THORNBACK, during
the period 13 July 1945 to 8 August, 1945, was conducted in the
northern areas east of Honshu and south of Hokkaido. The commanding
officer acted as commander of a coordinated group composed of the
THORNBACK, ANGLER and SEAPOACHER.

           2. The THORNBACK hugged the beach to obtain good area
coverage, but suitable torpedo targets were scarce.

           3. Following is a resume' of patrol high lights:

           (a). During the night of 23 July sight contact, in
moonlight, was made on a ship later identified as an enemy
submarine. While tracking and ending around, THORNBACK lost
contact when the enemy apparently submerged. Contact was not
regained.

           (b). On 26 July a small pinger was sighted and attacked.
This attack is covered by a special report. Later the same day
an approach was begun on a killer group of 2 SC's and a CH.
Contact was lost due to sun glare and could not be regained.

           (c). While submerged, on 27 July, a seagoing tug was
attacked. A special report covers this attack.

           (d). Another attack, covered by a special report, was
made the following day on a small Suger Dog type. Later the same
day a CIC and escort were sighted close inshore, but could not
be closed.

                               - 1 -

— page 72 —
SUBMARINE DIVISION THREE TWENTY-ONE

FB5-321/A16-3
Serial: (087)
C-O-N-F-I-D-E-N-T-I-A-L

Care of Fleet Post Office,
San Francisco, California,
10 August 1945.

FIRST ENDORSEMENT to
USS THORNBACK (SS418)
Conf. ltr. A16-3
Serial (032) dated
8 August 1945.

Subject: USS THORNBACK (SS418) - Report of FIRST War Patrol.

(e). On 29 July, after a surface approach in bad
visibility, five electric torpedoes were fired at a large sea
truck from 2300 yards, on an 85° track, with small gyro angles.
Depth was set at five feet. No hits resulted and the target
reached safety in a bay.

(f). After missing with three torpedoes set on three
feet, a sea truck was taken under fire in bad visibility.
Closing to 300 yards, THORNBACK hit repeatedly with 40MM, but
was unable to see target in 5" sights. The target, after
receiving considerable damage, closed the beach where THORNBACK
could not follow, and escaped in the fog.

(g). A well planned and boldly conducted coordinated
bombardment of Urakawa was carried out by THORNBACK, ANGLER,
and SEAPOACHER. In excellent visibility ships approached in
column to a range of 3200 yards at 18.5 knots. Four targets
were taken under fire and hit repeatedly. No fires were started,
but building interiors were evidently extensively damaged. A
large cloud of steam was noted after one hit which was suspected
as having come from a locomotive boiler.

4. THORNBACK returned from patrol clean and, with the
exception of #2 Main Engine, in excellent material condition.
Refit will be accomplished in the normal period.

5. The Commanding Officer, Officers, and Crew are
congratulated on the completion of this active patrol and on the
damage inflicted upon our tottering enemy.

[SIGNATURE: J. R. Waterman]
J. R. WATERMAN.

— page 73 —
FC5-32/A16-3
Serial: 0109
COMMANDER SUBMARINE SQUADRON THIRTY-TWO
Care of Fleet Post Office,
San Francisco, California.
14 August 1945
C-O-N-F-I-D-E-N-T-I-A-L

SECOND ENDORSEMENT to:
USS THORNBACK (SS418) Report
of First War Patrol Dated
8 August 1945.

From: The Commander Submarine Squadron THIRTY-TWO.
To: The Commander-in-Chief, United States Fleet.
Via: (1) The Commander Submarine Force, U.S. PACIFIC FLEET.
(2) The Commander-in-Chief, U.S. PACIFIC FLEET.

Subject: U.S.S. THORNBACK (SS418) - Report of FIRST War Patrol.

1. Forwarded, concurring in the remarks of the Commander Submarine
Division TWENTY-ONE.

2. In addition to the damage inflicted upon the enemy by the bombard-
ment of URAKAMI and the attack covered by a special report it is recommended
that the U.S.S. THORNBACK be credited with the following :

DAMAGED

1 - LIS (EU) 100 Tons (Gun attack # 1)

3. The Commanding Officer, officers and crew of the U.S.S. THORNBACK
are congratulated upon the completion of this active and well conducted first
war patrol and the damage to the enemy.

[SIGNATURE: K. C. HURD]
K. C. HURD.

— page 74 —
9 02251
FF12-10(A)/A16-3(18)
Serial 0 231

CONFIDENTIAL

THIRD ENDORSEMENT to
THORIBACK Report of
First War Patrol.

COMSUBSPAC PATROL REPORT NO. 859
U.S.S. THORIBACK - FIRST WAR PATROL.

From: The Commander Submarine Force, Pacific Fleet.
To : The Commander in Chief, United States Fleet.
Via : The Commander in Chief, U.S. Pacific Fleet.

Subject: U.S.S. THORIBACK (SS418) - Report of First War Patrol
(11 June to 8 August 1945).

1. The first war patrol of the U.S.S. THORIBACK, under the command
of Commander E. P. Abrahamson, U.S. Navy, was conducted in the areas off the east
coast of Honshu and the south coast of Hokkaido.

2. The mission of this patrol was mainly offensive patrolling for
enemy targets. Commander Abrahamson acted as commander of a coordinated subma-
rine group which conducted surface sweeps for picket boats in advance of the
Third Fleet's approach to the Honshu Coast. No contacts were made during these
sweeps. The THORIBACK covered her area in a very thorough manner and resorted
to close-in patrolling in endeavors to seek out worthwhile torpedo targets. Ex-
cept for a Japanese submarine which submerged before THORIBACK reached a firing
position, no worthwhile torpedo targets were encountered. In her endeavors to
inflict damage on enemy shipping THORIBACK fired torpedoes at small targets with
little success except for one instance. In a gun action conducted in dense fog
the THORIBACK attacked a small unidentified vessel which later escaped to waters
too shallow for THORIBACK to penetrate. The THORIBACK joined the U.S.S. ANGLER
(SS240) and the U.S.S. SEA POACHER (SS406) in a well conducted and damaging
coordinated bombardment of shore establishments at Urakawa.

3. Award of Submarine Combat Insignia for this patrol is not
authorized.

4. The Commander Submarine Force, Pacific Fleet, congratulates the
commanding officer, officers, and crew of the THORIBACK for the completion of
this patrol and regrets that this new and well trained ship was not favored with
more opportunities for inflicting damage upon the enemy. The THORIBACK is cre-
dited with having inflicted the following damage upon the enemy during this pa-
trol:

S U N K
1 - MIS (Small Patrol Boat) (EU) - 100 tons (Separate Report).

[STAMP: EXTRA]
[STAMP: SORG.]
[STAMP: PHOTO LAB]
[STAMP: RETURN TO F-4253]
[STAMP: ORIGINAL]
[STAMP: MICRO]
[STAMP: OP-16]
- 1 -
[HANDWRITTEN: Cut No 1.]
SUBMARINE FORCE, PACIFIC FLEET
mr
Care of Fleet Post Office,
San Francisco, California.
7 September 1945.

NOTE: THIS REPORT WILL BE
DESTROYED PRIOR TO
ENTERING PATROL AREA.

— page 76 —
END OF REEL
JOB NO. [HANDWRITTEN: H-108]

||| 1.0
||| 1.1
||| 1.25

||| 2.8 ||| 2.5
||| 3.2 ||| 2.2
||| 3.6 ||| 2.0
||| 4.0
||| 1.8

||| 1.4 ||| 1.6

THIS MICROFILM IS
THE PROPERTY OF
THE UNITED STATES
GOVERNMENT

[EMBLEM: DEPARTMENT OF DEFENSE, UNITED STATES OF AMERICA]

MICROFILMED BY
NPPSO-NAVAL DISTRICT WASHINGTON
MICROFILM SECTION