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Notable events involving Seahorse include:

2 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises in the San Francisco area.

3 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises in the San Francisco area.

4 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises in the San Francisco area.

11 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises in the San Francisco area.

16 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises in the San Francisco area.

17 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) departed the Mare Island Navy Yard for San Diego.

On leaving the San Francisco area the following morning she was joined around 0830T/18 by USS Lawrence (T/Cdr. T.B. Hutchins, 3rd, USN) as escort.

Around 0735T/19, USS Lawrence was relieved by USS Boyd (T/Cdr. U.S.G. Sharp, Jr., USN).

USS Seahorse and USS Boyd arrived at San Diego around 1445T/19.

20 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) departed San Diego for exercises. She returned to San Diego the following day.

22 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises off San Diego

23 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) departed San Diego for exercises. She returned to San Diego the following day.

25 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) departed San Diego for exercises. She returned to San Diego the following day.

27 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises off San Diego

28 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises off San Diego

29 Jun 1943
USS Seahorse (T/Cdr. D. McGregor, USN) departed San Diego for exercises. She returned to San Diego the following day.

1 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises off San Diego

2 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) departed San Diego for exercises with USS Crane (T/Cdr. H.N. Coffin, USN). They were escorted by USS PC-579 (Lt. F. Seymour, USNR).

On completion of the exercises USS Seahorse was to proceed to the Mare Island Navy Yard.

6 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) arrived at the Mare Island Navy Yard from San Diego.

7 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises in the San Francisco area.

16 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) departed the Mare Island Navy Yard for Pearl Harbour.

24 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) arrived at Pearl Harbour from the Mare Island Navy Yard.

27 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises off Pearl Harbour.

28 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) conducted exercises off Pearl Harbour.

29 Jul 1943
USS Seahorse (T/Cdr. D. McGregor, USN) departed Pearl Harbour for exercises with USS Allen (T/Lt.Cdr. H.H. Nielsen, USN) and USS Chickasaw (T/Lt. J.F. King, USN).

They remained out for night exercises.

In the morning of 30 July, USS Wahoo (T/Cdr. D.W. Morton, USN) joined the exercises.

On completion of the exercises in the afternoon of 30 July.

3 Aug 1943
Around 1500VW/3, USS Seahorse (T/Cdr. D. McGregor, USN) departed Pearl Harbor for her first war patrol. She was to patrol off the Palau Islands.

Before proceeding to her patrol area she was to top off with fuel at Johnston Island.

USS Seahorse was escorted out until dark by USS PC-589 (Lt.(jg) J.K. Miller, USNR). (1)

5 Aug 1943
Around 1130X/5, USS Seahorse (T/Cdr. D. McGregor, USN) arrived at Johnston Island to top off with fuel. She departed for her patrol area around 1530X/5. (1)

17 Aug 1943
Around 1100I/17, USS Seahorse (T/Cdr. D. McGregor, USN) arrived in her patrol area. (1)

18 Aug 1943
At 1135I/18, while patrolling three miles to the north of Malakal harbour, Palau, USS Seahorse (T/Cdr. D. McGregor, USN) sighted two small patrol vessels which located the submarine by echo ranging. At 1239I/18, a third patrol vessel, equipped with more powerful sound gear joined the other two. USS Seahorse sought refuge at 275 feet underneath a temperature gradient and evaded the enemy patrol craft.

20 Aug 1943
At 0750I/20, while patrolling five miles to the east of Peleliu, Palau, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a small diesel engined patrol craft which was echo ranging.

At 1107I/20, a two-masted, inter island type patrol vessel of about 1200 tons was sighted three miles to the east of Peleliu.

At 1452I/20, smoke was seen in position 07°01'N, 134°25'E. The source of the smoke was proceeding on a course of approximately 160°.

At 1845I/20, having surfaced, a high speed search of the area but no target was encountered and the search was abandoned at 2307I/21 and course was set to patrol in the vicinity of the Malakal passage. (1)

22 Aug 1943
At 0804I/22, while patrolling off the Malakal passage, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a patrol boat near the entrance of the passage. (1)

23 Aug 1943
At 0613I/23, while patrolling off the Malakal passage, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a small patrol boat.

At 0723I/23, USS Seahorse started the approach on a small steamer which was seen hull down. This turned out to be a patrol boat about 3.5 nautical miles from the Malakal harbour entrance.

At 1423I/23, another small patrol boat was sighted. (1)

24 Aug 1943
At 0122I/24, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a submarine chaser type patrol boat on the edge of a rain squall.

Two minutes later the enemy opened fire on the submarine from a range of about 1500 yards using flashless powder. The first two shots passed close to but over the conning tower. The next two exploded in the water abeam while USS Seahorse was crash diving. Six depth charges were subsequently dropped of which the last two were fairly close.

Around 0600I/24, the pinging of the submarine chaser was fading out.

At 2100I/24, the same ship was sighted at a range of 4000 yards and was evaded. (1)

25 Aug 1943
At 1016I/25, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a trawler type patrol boat at a range of 4000 yards. Contact was lost around 1330I/25.

At 2158I/25, a submarine chaser type patrol vessel was sighted at a range of 3000 yards. This vessel was evaded on the surface. (1)

26 Aug 1943
At 0501I/26, south-east of Babeldaub, Palau, in position 07°13'N, 134°41'E, USS Seahorse (T/Cdr. D. McGregor, USN) sighted two unidentified patrol vessels. To avoid being sighted USS Seahorse was forced to dive early.

At 1028I/26, an inter island type patrol vessel was sighted off the entrance to Malakal harbour. She remained in sight until around 1500I/26.

At 1030I/26, at least three sources of smoke were seen leaving Malakal harbour through the western entrance. (1)

28 Aug 1943
At 1003I/28, while off Malakal harbour, USS Seahorse (T/Cdr. D. McGregor, USN) picked up echo ranging from four different directions. Only some small patrol vessels were in sight.

At 1135I/28, in position 07°07'N, 134°25'E, masts were seen which developed into a convoy of three transports and two escorts. Range was 16000 yards. Enemy course was about 140°, speed 8 knots. It was not possible to close the range while submerged but increased speed to track and then surface after dark to overtake and attack.

At 1800I/28, USS Seahorse surfaced before sunset taking the chance of not being sighted by the enemy air patrol for the convoy. Proceeded at full speed.

At 2025I/28, contact on the convoy was regained. Tracked the convoy on a course of 140° at 8 knots. Commenced an end around to get ahead of the convoy to attack.

At 0502I/29, USS Seahorse dived ahead of the convoy.

At 0519I/29, USS Seahorse was about 4000 yards from the leading transport. One of the escorts obtained A/S contact and soon showed two green vertical lights and then turned towards at full speed. USS Seahorse went to full speed and changed course to complete the attack on the transport but the actions of the escort forced USS Seahorse to break off the attack and go deep.

Between 0525I/29 and 0539I/29, 15 depth charges were dropped the first 5 rather close. Both escorts were now hunting.

At 0717I/29, 4 depth charges, set deep, exploded which rocked USS Seahorse which was at 300 feet. Some minor damage was caused.

By 1000I/29, pinging started to fade out and at 1059I/28, USS Seahorse surfaced. SD radar showed 1 to 3 aircraft patrolling in the area. Commenced to search for the convoy while making some repairs to the induction piping when sea conditions permitted.

The convoy was not found again and at 1807I/30 the search for it was abandoned. Course was set to patrol off the Toagel Mlungui passage off the west coast of Babeldaob Island.

The convoy encountered was most likely ' Convoy Wekak 7 ' made up the transports Aden Maru (5860 GRT, built 1919), Hankow Maru (4104 GRT, built 1919), Nagano Maru (3810 GRT, built 1917), Nagato Maru (5901 GRT, built 1918) and Shinyu Maru (4614 GRT, built 1919) escorted by the submarine chasers Ch-26 and Ch-34 (all links are offsite links). (2)

31 Aug 1943
At 1531I/31, USS Seahorse (T/Cdr. D. McGregor, USN) sighted smoke bearing 018°. Commenced tracking.

At 1606I/31, a second source of smoke was sighted bearing 138°. This smoke was heavier and USS Seahorse was right on it's track.

At 1625I/31, USS Seahorse submerged and commenced an approach on the source of the smoke which was proceeding on a course of 320° at slow speed.

At 1800I/31, when about to complete the approach and then attack, the target turned on lights showing herself to be a hospital ship.

At 1825I/31, USS Seahorse surfaced and made off to search for the source of the smoke that had been sighted at 1531I/31. The search was abandoned around 0008I/1 after nothing had been encountered. (1)

3 Sep 1943
USS Seahorse (T/Cdr. D. McGregor, USN) commenced to patrol off the Toagel Mlungui passage off the west coast of Babeldaob Island. (1)

4 Sep 1943
At 0706I/4, off the Toagel Mlungui passage, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a small diesel patrol vessel which remained in the area until 1145I/4.

At 1755I/4, a two-funnelled steamer was seen leaving the Toagel Mlungui passage. The steamer proceeded on course 270° at 11 knots.

At 1850I/4, USS Seahorse surfaced and proceeded in pursuit of the steamer.

At 2010I/4, USS Seahorse overhauled the steamer but it was found to be a properly marked hospital ship. (1)

5 Sep 1943
At 0801I/5, near the Toagel Mlungui passage, USS Seahorse (T/Cdr. D. McGregor, USN) sighted an enemy patrol vessel.

At 0932I/5, an enemy transport was seen to be underway inside the reef. USS Seahorse proceeded to the front of the pass so as to be in position if this ship would come out.

At 1042I/5, a ship was seen outside the entrance to the pass and an attack was started but this was broken off when it was seen that the ship was a trawler type patrol vessel. The transport did not came out and must have relocated inside the reef. It could no longer be seen against the background of high hills and in the hazy rain. (1)

6 Sep 1943
USS Seahorse (T/Cdr. D. McGregor, USN) is damaged by depth charges while attacking a convoy off Palau in position 07°31'N, 134°21'E. Despite being damaged she was able to remain on patrol.

The ships attacked must have been from convoy ' No. 3111 ' (Manila - Palau) made up of 8 transports escorted by the destroyer Karukaya. Four of the transports have so far not been identified, the other four were the Maebashi Maru (7005 GRT, built 1921), Shinsei Maru No. 1 (5864 GRT, built 1919), Taian Maru (5755 GRT, built 1916), Tencho Maru (2716 GRT, built 1919).

Possibly on approaching Palau the convoy had split up to proceed to different anchorages reinforced by local escorts.

Despite the claim for three hits no damage was caused. Possibly this is yet another example of the premature exploding American torpedoes.

0715I/6 - While patrolling off the reef near the Toagel Mlungui passage off the west coast of Babeldaob, Palau, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a trawler type patrol vessel.

0836I/6 - Smoke was seen and a submerged approach was started.

0845I/6 - The smoke was seen to be originating from a convoy made up of two transports which were escorted by a patrol vessel and a gunboat which were approaching the Toagel Mlungui passage at 8 knots. An attack was started.

1045I/6 - In position 07°31'N, 134°21'E, USS Seahorse fired four bow torpedoes on one of the transports, estimated as being around 7500 tons and loaded with troops. Three hits were claimed and about 1.5 minutes after the last hit two heavy explosions were heard thought to be originating from the target. Three minutes after firing depth charging started. A total of 35 were counted and some were fairly close causing damage to USS Seahorse. Enemy course had been 035°, speed 7 knots. Range on firing was 2000 yards.

The enemy kept on hunting the submarine until around 1700I/6. (2)

7 Sep 1943
At 0506I/7, while closing the Toagel Mlungui passage from the north-west, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a patrol vessel which was difficult to see against the background. At the same time the SJ radar reported a contact at 2400 yards. USS Seahorse submerged and took avoiding action. Apparently she had not been sighted.

At 0545I/7, a second patrol vessel was heard and sighted. An efficient patrol by these two vessels kept USS Seahorse from approaching the reef. Apparently the enemy were on high alert after the attack on the convoy yesterday. (1)

10 Sep 1943
At 1014I/10, while patrolling of the Toagel Mlungui passage, USS Seahorse (T/Cdr. D. McGregor, USN) sighted the masts and funnel of a ship. An approach was started but on tracking the ship it became apparent that the ship was inside the lagoon and the approach was broken off.

At 1358I/10, in position 07°24'N, 134°16'E, to the south-west of the Toagel Mlungui passage, a convoy made up of two transports and a tanker were sighted. They were escorted by an armed merchant vessel, most likely and auxiliary gunboat. They were making for the Toagel Mlungui passage. An attack was started with the tanker as target. Due to the air escort it was decided to approach without using the periscope for a while. This was a costly mistake as after 13 minutes, during the next look it was seen that the convoy had made a zig away of about 55° and that the range had opened to 4200 yards. The attack was reluctantly broken off.

The ships sighted were most likely from convoy No. 2607 which had departed Balikpapan on 4 September.

This convoy was escorted by the destroyer Asakaze and auxiliary gunboat Manyo Maru (2904 GRT, built 1937). The convoy itself was made up of the transports Pacific Maru (5873 GRT, built 1920), Takaoka Maru (7047 GRT, built 1920), Yamayuri Maru (4910 GRT, built 1913), tankers Kyoei Maru (591 GRT, built 1937), Nissho Maru (10526 GRT, built 1938) and naval tanker Notoro. While en-route, on 8 September another destroyer [unidentified] and an auxiliary vessel had joined the convoy. The convoy arrived at Palau on 10 September. Most likely the convoy had split up before the ships were sighted by HMS Seahorse. (2)

11 Sep 1943
At 1112I/11, while patrolling of the Toagel Mlungui passage, USS Seahorse (T/Cdr. D. McGregor, USN) sighted an enemy patrol vessel.

As the three ships of the convoy that had been seen yesterday had all been laden Cdr. McGregor thought they might come out either today or tomorrow and would most likely turn northwards towards Japan. He had therefore positioned USS Seahorse in such a position as to intercept them.

At 1142I/11, when about 8 to 9 nautical miles to the north of the Toagel Mlungui passage a convoy made up of five ships and two escorts leaving the pass but instead of turning north the proceeded on course 280°. Commenced tracking them submerged being unable to attack.

At 1330I/11, an oiler, transport and an escort were sighted approaching from the south. They entered the Toagel Mlungui pass when the range was still 13000 yards. USS Seahorse meanwhile continued to track the convoy sighted earlier which was still proceeding westwards.

At 1715I/11, USS Seahorse surfaced and commenced an end around while keeping visual contact with the convoy. Had to dive twice for aircraft to avoid being sighted.

At 0300I/12, USS Seahorse submerged to approach the convoy. It was expected that 35 minnutes would be needed if the convoy continued on it's current course and speed. Nothing was however seen or heard from the convoy until .....

At 0410I/12, an escort started echo ranging close aboard while moving at slow speed. Nothing was seen as the weather and light conditions rendered periscope visibility almost zero.

At 0527I/12, USS Seahorse surfaced and continued tracking the convoy through frequent rain squalls.

At 0930I/12, contact was lost and course was set to return to the Toagel Mlungui passage. (1)

13 Sep 1943
At 0844I/13, near the Toagel Mlungui passage, in position 07°29'N 134°18'E, USS Seahorse (T/Cdr. D. McGregor, USN) sighted a transport of about 3000 tons in ballast at a range of 10000 yards. Decided not to attack as the range could not be sufficiently closed to attack this small target in ballast.

At 1138I/13, an enemy patrol vessel was sighted. (1)

14 Sep 1943
USS Seahorse (T/Cdr. D. McGregor, USN) twice attacked a large, 10000 tons, tanker to the west of Babeldaob, Palau. A total of eight torpedoes were fired but no hits were obtained.

Perhaps this was the Nissho Maru (10526 GRT, built 1938) which departed Palau for Truk in a convoy on this day.

0610I/14 - In position 07°31'N, 134°18'E, near the Toagel Mlungui passage, USS Seahorse sighted a large tanker. Commenced an attack.

0627I/14 - Fired four stern torpedoes. Four depth charges were the response. The tanker was observed to have changed course from 060° to 130°. Four bow tubes were now made ready. Enemy course was 076°, speed 12 knots. Range was 2900 yards.

0643I/14 - Fired four bow torpedoes. One ran erratically. Again four more depth charges were the enemy response. These were spread out over 25 minutes preventing USS Seahorse from observing the results of the attack. When last seen the tanker was proceeding on course 130° at 120 RPM which would put him on the reef soon. It is not known if any hits were obtained but it was though to be highly probable. Enemy course was 128°, speed 12 knots. Range was 4200 yards. (2)

16 Sep 1943
Around 2100I/16, USS Seahorse (T/Cdr. D. McGregor, USN) left patrol to proceed to Midway. (1)

27 Sep 1943
USS Seahorse (T/Cdr. D. McGregor, USN) ended her first, unsuccessful, war patrol at Midway. She was then taken in hand for repairs by the Submarine Base.

13 Oct 1943
From 13 to 17 October 1943, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) conducted exercises off Midway.

20 Oct 1943
At 1500Y/20, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) left Midway for her second war patrol. She was to patrol off South Honshu in Japanese home waters and in the East China Sea. (3)

29 Oct 1943
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) claimed the sinking of a 200 tons Japanese trawler to the south-west of Aogashima, Izu Islands.

0830I/29 - In position 30°52'N, 138°41'E sighted a trawler.

0917I/29 - Dived and closed the track of the target.

1055I/29 - Surfaced and commenced and end around run on completion of which, dived.

1417I/29 - Battle surfaced in position 31°24'N, 138°24'E. Opened fire at a range of 2400 yards. The target made radical course changes and there were very few hits for the first 20 rounds of 4". In all 50 rounds of 4" were expended for 17 hits. The superstructure of the trawler was completely gone and she was on fire from stem to stern. Besides the 50 rounds of 4" also 150 rounds of 20mm and 300 rounds of .50 cal. machine gun rounds were used.

1505I/29 - Ceased fire.

1537I/29 - The target was seen to sink. Nine men were seen in the water.

2005I/29 - Entered the first patrol area. (3)

30 Oct 1943
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) claimed the sinking of a 150 tons Japanese trawler well to the south of Wakayama Bay in position 30°48'N, 135°36'E.

0635I/30 - In position 30°48'N, 135°36'E sighted a trawler. Commenced to close to investigate.

0705I/30 - Dived and continued to close the target submerged.

1015I/30 - Surfaced to conduct high periscope patrol having decided to board the trawler at sunset.

1305I/30 - Dived with the target in sight. Carried out routines on the torpedoes.

1655I/30 - Battle surfaced at a range of 2500 yards and commenced to close the target. As it appeared the Japanese were preparing to repel a boarding party opened fire with the .50 cal machine gun. The first two rounds hit aft and the stern of the trawler soon went under. Fire was ceased when the Japanese had cleared to topside. A boarding party then went over in the rubber boat. They removed paperwork and charts as well as some gear and fresh fish. The trawler was then left in a sinking condition. The stern was under water to the aft part of the bridge and the trawler was still settling slowly. (3)

31 Oct 1943
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) claimed the sinking of a 150 tons Japanese trawler well to the south of Shikuku.

1412I/31 - Sighted a trawler in position 31°19'N, 134°16'E. Closed to investigate.

1418I/31 - Dived and continued to close the target.

1722I/31 - Battle surfaced after sunset at a range of 740 yards. The trawler made an attempt to ram but shooting was excellend and the third round of 4" blew the bridge of the trawler completely off. Continued to fire until the trawler was a blazing shambles.

1750I/31 - The trawler was seen to sink. No survivors were seen. (3)

2 Nov 1943
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) is credited to have sunk the Japanese troop transport Chihaya Maru and transport Yawata Maru out of a Japanese convoy. USS Seahorse also claimed to have sunk a large tanker but there was no tanker present in the convoy. [At least two of the transports in the convoy had their engines aft and thus may have been mistakenly identified as a tanker.]

The convoy attacked was convoy O-112 en-route from Saeki to Palau. It was made up of the transports Chihaya Maru (former Dutch Tjisaroea, 7089 GRT, built 1926), Delagoa Maru (7148 GRT, built 1919), Ehime Maru (4655 GRT, built 1920), Hozugawa Maru (1925 GRT, built 1941), Kanjo Maru (2186 GRT, built 1918), Moji Maru (3757 GRT, built 1922), Nichiai Maru (5443 GRT, built 1919), Tencho Maru (2716 GRT, built 1919), Ume Maru (5860 GRT, built 1919), Umekawa Maru (1931 GRT, built 1939), Yamagata Maru (3792 GRT, built 1916) and Yawata Maru (1852 GRT, built 1935).

The convoy was escorted by the minesweeper W-18, auxiliary submarine chasers Chiyo Maru No.8, Takunan Maru No.8 and the auxiliary minesweepers Aoi Maru, Takunan Maru No.3 and Tokuho Maru No.10.

It is possible more escorts were present. Most of the escorts apparently parted company during the night of 1/2 November. USS Seahorse reported seeing two 'Chidori-class' torpedo boats but the more modern Japanese W-class minesweepers looked very much like these torpedo boats so perhaps, besides W-18 another minesweeper was present.

2315I/31 - In position 31°48'N, 134°49'E obtained radar contact bearing 301° at a range of 16000 yards. Closed to investigate.

After four hours of tracking it was obvious that this was a large convoy. The radar operators were unable to keep contact on a single target but the course and speed of the convoy could non the less be determined.

0315I/1 - Dived ahead of the main body of the convoy at a range of 5000 yards, 2200 yards off track with the intention to get to the screen at radar depth and attack the main convoy with torpedoes.

During the approach a high, narrow black shape was seen close aboard and Seahorse had no other choice than to go deep and break off the approach. No A/S attack developed.

0405I/1 - Surfaced and commenced an end around run.

0505I/1 - Reached a position forward of the beam of the main body of the convoy. Dived as it was getting light. Ran in at high speed and by the time it was light enough to see well through the periscope Seahorse was in a good position to examine the entire convoy. 17 ships were in sight including escorts but there may have been more. Only the tops of the ships in the far column were visible and most likely the escorts beyond could not be seen. A 'Chidori-class' torpedo boat was on the port bow patrolling station with another 'Chidori-class' on the port beam. Patrol craft (PC's) were close to the main body of the convoy. A large tanker, passenger freighter and two large transports were in the lead.

0705I/1 - While waiting for the convoy to get clear distant depth charging commenced.

0900I/1 - Heard pinging. Sighted two 'Chidori-class' torpedo boats conducting a coordinated sound search of the area.

1030I/1 - Heard two distant depth charge explosions. The 'Chidori's' were both in sight with the closed one at 6000 yards. It was noticed that it were not the 'Chidori's' which were dropping depth charges.

1308I/1 - The 'Chidori's' were seen to join up and make off in the direction of the convoy at high speed.

1345I/1 - The 'Chidori's' were no longer in sight so surfaced and proceeded at maximum speed in the direction they made off.

1527I/1 - Sighted the tops of the 'Chidori's' and manoeuvred to keep them in sight. Their base course was about 180°.

1615I/1 - The 'Chidori's' both let out a puff of smoke and suddenly disappeared. Seahorse went to full speed on all four engines to follow them on course 180°.

2010I/1 - Obtained radar contact bearing 169° at 18000 yards. Commenced to work up to gain a position ahead of the convoy.

2200I/1 - In position 8000 yards on the starboard bow of the leading large ship when four orange flashes were seen in the rear of the convoy. Many distant depth charge explosions were heard and a searchlight display was witnessed by the bridge watch. It was obvious another American submarine must have made an attack [this was the work of USS Trigger (T/Lt.Cdr. R.E. Dornin, USN)]. Radar reported that the convoy was scattering and increasing speed.

Recommenced a night surface radar approach. Decided to attack a group of two large ships and three escorts. These escorts were very active and managed to be in the wrong place each time USS Seahorse started an attack run. After trying to attack from both beams finally reached an attack position on the port bow of a passenger freighter and at .....

0048I/2 - In position 28°37'N, 134°47'E, fired three bow torpedoes at the target from 3700 yards, the passenger freighter resembling the Hakone Maru of over 10000 tons. It was the intention to also fire three bow torpedoes at the other, leading, target, a freighter. The port escort however came directly towards at a range of 2100 yards and there was no more time to fire the remaining three bow torpedoes at the freighter. Immediately after firing radar range to the escort was only 1700 yards and he must have seen us. Three hits on the target were then observed and the stern was seen to break off. The stern was seen to sink immediately and the bow rose high in the air before it sank.

0114I/2 - Commenced investigating radar pips on several bearings at various ranges. While attempting to get into an attack position on a single large ship, and having great difficulty in getting past the escorts, the radar picked up two good pips at 10000 yards and target was shifted. This contact proved to be a large tanker and a relatively small freighter with two escorts well on the starboard side of the targets. Escorts and targets were proceeding on a course of 155°. It was very dark around this time and no difficulty was experienced to reach a good firing position.

0418I/2 - In position 28°37'N, 134°45'E, commenced firing three bow torpedoes at each of the targets from ranges of 2200 and 1700 yards. Pulled out to port and waited for hits. Two hits were observed on each target. One in the aft part of the tanker caused a violent explosion. The escorts closed rapidly and they closed to 1700 yards before range started to increase again. The tanker was closed to 300 yards before she stopped dead in the water settling by the stern.

0425I/2 - Radar reported one of the targets sinking at a range of 5000 yards. Changed course to close the remaining target to finish this ship off with a stern torpedo.

0426I/2 - One escort dropped a depth charge near the firing point while another escort was laying stopped near the point where the freighter had sunk. This escort was showing two bright green, all round, lights on his foremast.

0431I/2 - A violent explosion was observed in the tanker which caused her to burst into flames. The radar pip was decreasing and the tanker was seen to be low in the water.

0445I/2 - The tanker sank and it's radar pip disappered. Range was 8000 yards. The flames persisted indicating that oil on the water was on fire. There was still radar contact with the single target but it was not possible to reach an attack position before daylight.

0518I/2 - Dived. Depth charging continued until 0845I/2. The last ships were lost from sight at 1205I/2.

1323I/2 - Picked up HE of screws but could not see anything until .....

1403I/2 - A patrol craft (PC-type vessel) was seen approaching from the direction of the convoy.

1455I/2 - When the patrol craft was out of sight surfaced and went after the convoy with the hope of regaining contact.

0635I/3 - Not having obtained contact broke off the chase. (4)

4 Nov 1943
At 2242I/4, in position 29°50'N, 130°00'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) obtained radar contact at a range of 14000 yards. Three small pips were seen which looked like a convoy. The range was closed to 9000 yards when it was noticed that four ships were present making 9 knots on various courses. By the time the range had been closed to 7000 yards the ships were identified as patrol vessels. They were evaded. (3)

6 Nov 1943
At 0823I/6, in position 31°08'N, 128°00'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a fishing sampan which was avoided. (3)

8 Nov 1943
At 0730I/8, in position 32°18'N, 126°56'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a lighted fishing sampan which was avoided.

At 1251I/8, in position 31°44'N, 127°14'E, two fishing sampans were sighted which were avoided. (3)

9 Nov 1943
At 0040I/9, in position 31°38'N, 128°07'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted four lighted fishing sampans which were avoided. (3)

10 Nov 1943
At 1225I/10, in position 32°15'N, 128°15'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted two fishing large trawlers which were avoided. (3)

11 Nov 1943
At 0236H/11, in position 32°20'N, 127°32'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a fishing sampan which was avoided.

At 0845H/11, in position 32°08'N, 126°51'E, USS Seahorse sighted a fishing sampan which was avoided.

At 1347H/11, in position 32°14'N, 127°04'E, USS Seahorse sighted a fishing sampan which was avoided.

At 1915H/11, in position 32°15'N, 127°05'E, USS Seahorse sighted a lighted fishing sampan which was avoided. (3)

12 Nov 1943
At 1441H/12, in position 32°17'N, 127°11'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a fishing sampan which was avoided.

At 1825H/12, in position 32°14'N, 126°54'E, USS Seahorse sighted a lighted fishing sampan which was avoided. (3)

13 Nov 1943
At 0132H/13, in position 33°16'N, 127°30'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted an enemy patrol vessel which was avoided. This patrol vessel produced quite a lot of smoke.

At 1730H/13, in position 33°50'N, 127°29'E, USS Seahorse sighted smoke bearing 210°. Distance was estimated to be about 15 nautical miles.

At 1745H/13, USS Seahorse surfaced and proceeded on course 120° to head off the target.

At 1858H/13, course was altered to 180° but the target was not sighted.

At 1952H/13, in position 33°31'N, 128°16'E, smoke was sighted bearing 130°. Changed course and went to full speed to head off the target.

At 2003H/13, radar picked up the target at 18000 yards. Course of the target was 100° at 14 knots. An escort was sighted on the port beam of the target. USS Seahorse commenced an end around to get ahead of the target.

At 2130H/13, the end around was abandoned as it would be impossible to get ahead of the target before it would enter coastal waters. It was thought the target was a fairly large ship. (3)

14 Nov 1943
At 0200H/14, in position 33°21'N, 127°38'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted an enemy patrol vessel which was avoided.

At 1125H/14, in position 33°03'N, 126°56'E, USS Seahorse sighted a fishing sampan which was avoided. (3)

15 Nov 1943
At 0928H/15, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a ship bearing 185° at a range of 7000 yards. Fog was just lifting at that moment. Target course was estimates as being 090° at just 3 knots.

At 1000H/15, when visibility had improved further and the range had been closed to 4000 yards it was seen that the target was aground, high and dry on a reef in position 33°31'N, 126°58'E. No further action was needed as the ship was clearly beyond salvage. (3)

16 Nov 1943
At 0047H/16, in position 32°30'N, 128°21'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a lighted fishing sampan which was avoided. (3)

17 Nov 1943
At 0136H/17, in position 32°16'N, 129°15'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted smoke bearing 144°.

By 0140H/17, it was determined that the source(s) of the smoke was making for Nagasaki, proceeding on course 050°. Increased speed to 17 knots to close the target.

At 0145H/17, USS Seahorse altered course to 115° and increased speed to the maximum to get ahead of the targets as it was soon seen that it was a convoy of two transports and two escorts.

At 0219H/17, radar had not been working properly and contact was now lost on one of the escorts. This was soon seen from the bridge to be a destroyer which was coming directly towards at high speed. USS Seahorse turned stern on when the range was 5500 yards. The range kept closing rapidly so USS Seahorse dived. The convoy meanwhile had changed course. The destroyer was hunting overhead with frequent course and speed changes made it impossible to attack her with torpedoes. The destroyer made several dummy attack runs but at .....

0329H/17, dropped a pattern of seven depth charges but they were not close. Only some cork and paint came off.

0406H/17, the destroyer was still in contact despite frequent depth changes by USS Seahorse which set a course to clear the area to the south-west.

0421H/17, the destroyer dropped four depth charges after several practice runs. They exploded very close. The submarine was shaken very severely and some light bulbs were broken but no serious damage was sustained. USS Seahorse went to full speed and made a radical course change and the destroyer lost contact.

0630H/17, the destroyers screws faded out.

0710H/17, heard to distant depth charge explosions.

0755H/17, saw an aircraft circling the destroyer which was now also seen to be closing again.

0840H/17, the destroyer passed close aboard but she did not gain contact though definitely hunting.

1410H/17, the destroyer cleared the area.

1810H/17, now surfaced radar contact was obtained on what is thought to be a patrol vessel steering courses between 070° and 250°. This was avoided. Position was 31°53'N, 128°54'E. (3)

19 Nov 1943
At 1010H/19, while on the surface in position 31°14'N, 128°56'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a plane coming out of low cloud at a short distance. Crash dived.

At 1011H/19, the aircraft, a two engine float plane, dropped two bombs that well aimed and some minor damage was caused.

USS Seahorse patrolled submerged for the remainder of the day during daylight surfacing at 1755H/19. (3)

21 Nov 1943
At 0844H/21, a two-masted sailing vessel was sighted by USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) in position 34°09'N, 127°50'E. It was avoided.

At 0857H/21, another two-masted sailing vessel was sighted in position 34°06'N, 127°49'E. It too was avoided.

At 1609H/21, in position 34°18'N, 127°47'E, smoke was sighted which was drawing right. Range was estimated as being 15000 yards. Course was set to close.

By 1835H/21, it was apparent, through tracking, that the contcat must be a very small vessel and the approach was broken off in position 34°24'N, 128°04'E. (3)

22 Nov 1943
USS Seahorse (Lt.Cdr. S.D. Cutter) torpedoed and sank the Japanese transport Daishu Maru (3099 GRT, built 1919) out of a convoy in the East China Sea west of the Tsushima Strait in position 33°41'N, 128°35'E.

0117H/22 - In position 33°39'N, 128°42'E sighted smoke and immediately commenced to close. The contact developed into a convoy made up of three small transports and two destroyers.

0208H/22 - Dived 2700 yards of the convoys track. Range to the leading transport was 12000 yards. A quick plot put the convoy on course 105° at 9 knots. USS Seahorse ran at radar depth but the radar failed to give results until the range had closed to 2200 yards. When the range was 1830 yards on the largest ship came to periscope depth to complete the attack.

0245H/22 - in position 33°36'N, 128°35'E, commenced firing four torpedoes at transport of around 4000 tons from 1500 yards. Two hits were obtained. The target was seen to be obscured by smoke but USS Seahorse had go deep as the destroyers were rapidly closing.

0329H/22 - Seven extremely heavy depth charges exploded but not close. The destroyers were not in contact.

0405H/22 - Six more depth charges exploded. USS Seahorse was now at periscope depth but nothing could be seen.

0418H/22 - Surfaced. A destroyer was seen milling around on the port quarter. The enemy was put stern on and USS Seahorse retired at full speed.

0517H/22 - Sighted a sampan.

0518H/22 - Dived and remained dived until 1735H/22. (3)

24 Nov 1943
At 2352H/24, in position 31°27'N 128°02'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a lighted fishing sampan which was avoided. (3)

25 Nov 1943
At 0005H/25, in position 31°27'N 128°01'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a lighted fishing sampan which was avoided.

At 0032H/25, in position 31°25'N 127°52'E, USS Seahorse sighted a lighted large trawler which was avoided.

At 0718H/25, in position 30°38'N 127°21'E, USS Seahorse sighted a fishing sampan which was avoided. (3)

26 Nov 1943
At 0916H/26, in position 33°24'N 127°27'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted a fishing sampan which was avoided. (3)

27 Nov 1943
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) attacked a convoy and torpedoed and sank the Japanese tanker San Ramon Maru (7309 GRT, built 1935) in the East China Sea in position 33°36'N, 128°57'E.

Lt.Cdr. Cutter claimed to have sunk a second large tanker but this claim could not be confirmed post war.

San Ramon Maru was in convoy No. 221 which was en-route from Formosa to Moji, Japan, which also consisted of the tankers Taketoyo Maru (7028 GRT, built 1920), Fushimi Maru No.3 (4289 GRT, built 1943) and the transports Chile Maru (5860 GRT, built 1919), Shoyu Maru (853 GRT, built 1943), Seiwa Maru (1315 GRT, built 1917) and one so far unidentified merchant ship. They were escorted by patrol boat PB-36.

1045H/26 - Sighted smoke bearing 295°.

1315H/26 - Heard echo ranging bearing 305°. No ships were in sight but three sources of smoke were visible.

1416H/26 - Sighted a two-engined bomber patrolling over the convoy. There were still no ships in sight. Lt.Cdr. Cutter decided to run submerged parallel to the convoy during daylight hours and then surface after sunset to attack the convoy on the surface.

1720H/26 - Surfaced and set off in pursuit of the convoy.

1755H/26 - Obtained radar contact bearing 083° at a range of 19900 yards.

1823H/26 - Sighted large ships. Commenced tracking them with radar. Base course of the convoy was 100° at 10 knots. The convoy was seen to be made up of two large tankers and three escorts, one ahead, one on the starboard quarter and one astern. There was no moon but the night was clear and not dark.

2250H/26 - Commenced a surface attack.

2302H/26 - In position 33°36'N, 128°57'E fired the last three bow torpedoes at the leading tanker from 3900 yards. Two hits were obtained. The tankers amidships section exploded, the stern section drifted clear and the bow sank immediately. The stern section sank soon afterwards. The closest escort turned towards and chased Seahorse eastwards but eventually lost contact after which Seahorse started an attack on the second tanker.

0025H/27 - In position 33°38'N, 129°05'E, fired four stern torpedoes from 3300 yards. Two hits were heard. About 10 seconds later flames were seen to spout out all over the tanker followed by a massive explosion. The tanker went up in a huge mushroom of flames. The mushroom was at least 3000 feet high and pieces of the tanker sprayed the entire area. An escort nearby the tanker stopped according to the radar and was still stopped when radar contact was lost. It was thought the escort may have been hit and disabled by a piece of the tanker.

USS Seahorse then left patrol to proceed to Midway.

At 0106H/27, in position 33°26'N, 128°53'E, two sampans were seen and avoided.

29 Nov 1943
At 1022I/29, in position 30°21'N, 135°54'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighed a trawler which was closed submerged. The trawler was seen to be armed and had a radio mast, obviously a picket boat. No attack was made. (3)

1 Dec 1943
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) attacked a Japanese convoy and claims the possible sinking of medium sized transport ship off the Bonin Islands chain.

At 0540I/30, USS Seahorse sighted smoke. She then closed to investigate. Visibility improved and a convoy was sighted. As USS Seahorse was too close the range was opened and USS Seahorse commenced tracking and an end around run.

At 1052I/30, in position 31°09'N, 140°38'E, a large plane was sighted at a range of 8 miles. USS Seahorse dived. It had just been seen that the convoy consisted of three medium sized transports with a small transport and a patrol vessel as escorts. Their base course was about 170°.

By 1500I/30, USS Seahorse was abeam of the convoy at a range of 5000 yards. It was decided to attack on the surface at night.

1721I/30, Surfaced. Smoke was still sighted. Commenced to close at maximum speed.

1829I/30, Obtained radar contact at 6850 yards. The targets were zigzagging wildly with the escorts patrolling up and down the flanks of the convoy. Several attack runs were spoiled by the targets frequent change of course.

2234I/30, USS Seahorse, which only had stern tubes loaded, was no ahead of the convoy at a range of 1940 yards and about to open fire when the convoy made it next zig when at .....

2242I/30, the starboard escort turned on a red light.

2244I/30, Three ships commenced firing on USS Seahorse. The closest shell landed about 300 yards away. The convoy did not break up and made a course alteration.

0033I/1, USS Seahorse was in firing position.

0034I/1, the target zigged away 10°.

0038I/1, In position 28°34'N, 140°47'E, fired four torpedoes at a transport of about 5000 tons from 3650 yards. One torpedo exploded prematurely about 50 seconds after the first torpedo had been fired. The starboard escort turned on a red light and all ships promptly opened fire. As no shells landed close they were probably firing at random. The great number of explosions and visibility made it however impossible to observe the result of the attack. USS Seahorse had gone to full speed immediately after firing and the target was soon lost in the haze. Depth charges were heard exploding but also other explosions were heard. Six minutes after firing, which was too long for the torpedo run, two brilliant flashes were seen in the direction of the target and the resulting explosion was heavy but it is not known what these were. After the attack only three pips were seen on the radar screen which had reversed course. Two transports and an escort. The patrol vessel type escort was thought to have possibly be no longer in range.

0120I/1, USS Seahorse was back in the vicinity of the position of the attack. Radar contact was obtained on the patrol vessel type escort at a range of 5600 yards on the approximate bearing where the attack had been made. It was thought this escort may be searching for survivors.

0126I/1, USS Seahorse left the area to continue her passage to Midway. (3)

7 Dec 1943
Around 1500Y/7, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) arrived at Midway. (3)

8 Dec 1943
Around 1300Y/8, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) departed Midway for Pearl Harbour. (3)

12 Dec 1943
Around 1100VW/12, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) ended a successful second war patrol at Pearl Harbor. She was taken in hand for post patrol repairs / refit by the submarine base.

27 Dec 1943
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) is docked in the floating dock ARD-1 at Pearl Harbour.

[Date of undocking currently not known to us.] (5)

2 Jan 1944
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) completed three days of training off Pearl Harbour.

3 Jan 1944
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) conducted sound trials at / off Pearl Harbour.

6 Jan 1944
Around 1100VW/6, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) left Pearl Harbor for her third war patrol. She was to patrol off the Palau Islands.

8 Jan 1944
Around 0900X/8, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) arrived at Johnston Island to top off with fuel. Around 1400X/8 she left to continue the passage to her patrol area. (5)

16 Jan 1944
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) attacked a Jananese convoy and torpedoed and sank the Japanese transport Nikko Maru (784 GRT, built 1942) east-south-east of the Mariana Islands in position 12°49'N, 150°19'E.

0900K/16 - In position 13°03'N, 149°07'E smoke was sighted through the high periscope bearing 323°. Commenced an end around run. The course of the target was determined to be around 118°.

1014K/16 - Dived ahead of the target.

1207K/16 - The target was now identified as a convoy made up of a medium sized transport escorted by two patrol vessels and two trawler type escorts.

1226K/16 - USS Seahorse was now dead ahead of the target at a range of 12000 yards.

1308K/16 - USS Seahorse was now in an excellent firing position for a stern tube shot from 1950 yards. However the target changed course and the attack had to broken off. All escorts were pinging and within 800 yards but apparently did not detect the submarine. One of them however remained behind for no apparent reason.

1354K/16 - Received a close depth charge without any previous warning.

1355K/16 - A second depth charge was dropped followed by another one three minutes later.

1402K/16 - A fourth depth charge was dropped, very close followed by another one 30 seconds later. This one too was very close.

1437K/16 - A sixth depth charge was dropped, a 'block buster'. No more depth charges were dropped after this one.

1546K/16 - Returned to periscope depth. Nothing was in sight.

1607K/16 - Surfaced and proceeded in pursuit of the convoy at four engines.

1638K/16 - Sighted smoke and commenced an end around run.

1838K/16 - Obtained radar contact at a range of 15000 yards.

1944K/16 - USS Seahorse was now ahead of the target at a range of 12100 yards. The convoy was now doing only small zigs on a base course of 180° at 9.5 knots.

2010K/16 - In position 12°49'N, 150°19'E, fired four torpedoes at the target from 2500 yards, thought to be a transport of about 6500 tons. Three hits were obtained and the ship broke in two. It was thought to be a new type of transport looking a bit like a Liberty ship.

2016K/16 - Radar reported that the target had sunk. The escorts were milling around near the position of the sinking dropping depth charges at random.

2136K/16 - USS Seahorse set course for Fais Island, Caroline Islands.

19 Jan 1944
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) conducted a periscope reconnaissance of Fais Island, Caroline Islands. A series of 25 photographs were taken through the periscope. (5)

20 Jan 1944
At 1318I/20, in position 06°09'N, 135°48'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighed a trawler type patrol vessel was sighted which was avoided. (5)

21 Jan 1944
USS Seahorse (Lt.Cdr. S.D. Cutter) attacked a Japanese convoy and torpedoed and sank the transports Ikoma Maru (3156 GRT, built 1925) and Yasukuni Maru (3021 GRT, built 1920) about 280 nautical miles east-south-east of Palau in position 03°19'N, 137°02'E.

These ships were en-route from Palau to Wewak and were escorted by the submarine chaser Ch-32 and the auxiliary submarine chaser Cha-47.

0610I/21 - USS Seahorse commenced to patrol on the Palau - Wewak route.

1231I/21 - A puff of smoke was seen through the high periscope bearing 085°. Turned towards the contact until a ship was in sight. Commenced an end around run.

1312I/21 - Sighted the tops of two ships through the periscope. Neither ship was smoking and it was difficult to keep track of them due to numerous rain squalls. During the remainder of the afternoon only three puffs of smoke were seen coming from the targets.

1411I/21 - Sighted a patrol vessel on the closest side of the convoy. Commenced an end around run on this escort. The convoy was not in sight for three hours but it's base course was assumed to be 140° at a speed of 9 knots. USS Seahorse continued to keep working up ahead of the convoy.

1617I/21 - Sighted the convoy.

1625I/21 - Dived and commenced a submerged approach on the convoy. As the convoy came in sight the two targets were in line of bearing and zigzagging independently. A patrol vessel was on the starboard quarter of the largest ship. Both transports were heavily laden, event their decks were piled up with cargo. Due to their relative positions it was not possible to attack them both on one attack run. Decided to attack after dark on the surface. Pictures were taken of the closest ship.

1900I/21 - Surfaced and commenced a night radar approach.

1913I/21 - Target range was now 18750 yards. Four pips on the radar screen.

2026I/21 - Target range now 11650 yards. The transports were visible through binoculars. A third escort was now detected on the radar screen. The two transports were still zigzagging independently from each other. Two escorts were 2500 to 4000 yards ahead of the tranports with the third escorts 1500 yards astern of the transports.

2109I/21 - USS Seahorse was now abeam of the largest transport at a range of 8750 yards. Commenced going in an an attack run. All ships of the convoy were in sight.

2123I/21 - Range was now 2900 yards when the target zigged 45° away. USS Seahorse reversed course to open the range. Range was opened to 4500 yards from where another attack run started.

2137I/21 - In position 03°19'N, 137°02'E, fired three torpedoes at the largest transport from 2800 yards. The second ship was also in line of fire but a little to the left at at a range of 3600 yards.

2139I/21 - Two hits were observed on the target followed 20 seconds later by a hit in the stern on the second transport. Both transports came to a halt and started firing their guns in every direction. The escorts started dropping depth charges at random.

2200I/21 - USS Seahorse stopped within visible distance of the targets to await developments. One of the escorts was en-route from the near target to the far one. Other escorts kept going.

2206I/21 - Radar reported that the second target was settling. The other target, the largest ship, was low in the water but still on an even keel. It was decided to attack again with two torpedoes.

2228I/21 - Fired two bow torpedoes from 3120 yards at the target which was dead in the water. The escort chased the torpedo wakes but away from the submarine. Both torpedoes missed.

2240I/21 - The smaller target was well down by the stern with only the forward part in sight. Started another attack on the larger target with two torpedoes.

2245I/21 - Fired two torpedoes from 2600 yards. Again both missed and it was found out that there was a problem with the torpedo firing control equipment. Again it was decided to attack again now using the stern tubes.

2320I/21 - The smallest ship was seen to sink stern first.

2324I/21 - Fired two stern torpedoes from 2250 yards. Both hit and the target blew up. (6)

22 Jan 1944
At 1845I/22, in position 04°34'N, 138°45'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighted and obtained radar contact on what is thought to be a small patrol vessel. It was avoided. Range was 7750 yards. (5)

25 Jan 1944
At 0607I/25, south-east of Palau, in position 06°56'N, 134°47'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighed two PC-type patrol vessels proceeding on a course of 070°. USS Seahorse passed between them. Only one was pinging. When the range had opened to 4000 yards commenced following them in the hope they were going to meet an incoming convoy.

0804I/25, Sighted two large sampans, one 1500 yards away and one 3000 yards away. Both were a nuisance for the remainder of the morning making it impossible to show much periscope in the flat calm sea.

1019I/25, in position 07°05'N, 134°50'E, sighted smoke bearing 020°. There were three sources of smoke. Commenced approach but it was soon apparent that the ships were coming down from the north and were following the reef. It was not possible to close them sufficiently to identify them. Air cover was observed over this convoy.

1300I/25, Sighted smoke.

1327I/25, Heard pinging and sighted a large converted yacht type patrol craft proceeding on course 130° at 10 knots. Decided to trail him in the hope he would meet an incoming convoy. Position was 06°55'N, 134°45'E.

1858I/25, Surfaced and proceeded on the last bearing of this yacht type patrol vessel. The SJ radar was defective despite repair efforts that had been undertaken. (5)

27 Jan 1944
At 1301I/27, in position 07°08'N, 134°38'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighed a ship coming from the Malakal Passage. Commenced approach but broke off this approach four minutes later when it was seen that the ship was a properly marked hospital ship.

At 1452I/27, in position 07°07'N, 134°37'E, a two-masted trawler with auxiliary sails forward and aft was sighted. (5)

28 Jan 1944
At 1413I/28, in position 07°10'N, 134°34'E, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) sighed three trawler-type patrol vessels conducting an A/S sweep off the Malakal Passage. All were pinging. They approached to about 1500 yards from USS Seahorse at times.

At 1700I/28 sound and sight contact with these patrol boats was lost and most likely they had returned to the Malakal anchorage. (5)

30 Jan 1944
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) attacked a Japanese convoy and torpedoed and sank the Japanese transport Toko Maru (2748 GRT, built 1940) south-east of Palau in position 06°10'N, 138°14'E.

Toko Maru was part of a convoy from Palau to Rabaul which was further made up of the transport Toei Maru (4004 GRT, built 1937), auxiliary store ship Hokkai Maru (408 GRT, built 1934), tankers Takatori Maru No.2 (521 GRT, built 1931) and Taiei Maru (?). They were escorted by the submarin chasers Ch-16, Ch-34, Ch-35 and Ch-40 and the auxiliary submarine chasers Cha-47 and Cha-61. Following the sinking of the Toko Maru, CH-34 returned to Palau.

1719I/28 - Smoke was sighted bearing 313° in the direction of the Malakal Passage.

1738I/28 - Two more sources of smoke were sighted in the direction of the Malakal Passage.

1755I/28 - A patrolling aircraft was sighted in the direction of the smoke.

1800I/28 - It was seen that the smoke was coming from a convoy made up of three transports and five escorts coming down the Malakal Passage. Shortly afterwards three sources of echo ranging were reported coming from the direction of the convoy.

1940I/28 - USS Seahorse surfaced and commenced an end around.

2110I/28 - USS Seahorse was ahead of the convoy which was on a base course of 100° at 8 knots. Commenced approach. The transports were zigzagging between 060° and 160° with two escorts on either flank and one astern. Between 2110I/28 and 0410I/29, USS Seahorse made six approaches but each time the well placed escort spoiled the completion of the attack run.

0410I/29 - Broke off the attempts to attack and worked ahead of the convoy to dive for a submerged approach.

0600I/29 - Sighted the tops of the convoy bearing 312°. Attempted to gain a position ahead and wait for the daily change in base course before diving for a submerged attack.

0723I/29 - Sighted a two-engined Japanese bomber acting as air cover for the convoy. Dived.

0915I/29 - Surfaced.

0937I/29 - Sighed smoke of the convoy.

1000I/29 - Sighted the Japanese bomber again. Dived and ran in submerged at 6 knots maintaining position on the flank of the convoy by bearing of the pinging escorts.

1206I/29 - Sighted the bomber through the periscope. Also took periscope observation of the convoy from a range of 12000 yards. Decided to attack tonight.

1823I/29 - Surfaced and set course on the last bearing of the pinging.

1925I/29 - Obtained radar contact on the convoy.

2130I/29 - In position ahead of the convoy at a range of 16000 yards. Waited for moonset while running ahead of the convoy at their speed.

2145I/29 - Moonset. Commenced approach.

2153I/29 - Range was now 12500 yards. Picked up part of the escort on radar, one at a range of 10500 yards and one at 7900 yards.

2156I/29 - Obtained contact on a third escort at a range of 8250 yards. During three approach runs the same problem as the night before was encountered, well placed escort vessels.

0132I/30 - The convoy made a radical zig to the right and this threw the two escorts on his port beam far back on his quarter. This was the opportunity to attack so a race now commenced between the escorts trying to regain station and USS Seahorse trying to reach a favourable attack position.

0149I/30 - USS Seahorse won the race due to her superior speed so three bow torpedoes were fired from 2600 yards at the leading transport.

0151I/30 - Three hits were observed with the third torpedo blowing the stern off and the first two stetting the target on fire. The target was seen to sink eight minutes later.

0159I/30 - Maintained radar contact on the convoy until light conditions forced USS Seahorse to open the range. As the convoy was now over 300 miles from Palau it was thought that no air cover would be with the convoy today.

0542I/30 - Lost radar contact. Slowed down to lower the sound gear to obtain the bearing of the convoy from the pinging of the escorts but nothing was heard.

0625I/30 - Sighted an escort vessel. Decided to follow it as contact with the convoy had been lost.

0934I/30 - Sighted convoy bearing 299° and to our surprise the convoy had reversed course and was now in the position of last nights sinking.

0950I/30 - Sighted a Japanese bomber patrolling near the convoy. As Palau was too far away it was probably based at Woleai Island.

1035I/30 - The escorts again commenced to ping allowing USS Seahorse to remain in contact with the convoy.

1525I/30 - Sighted a Japanese bomber still providing air cover for the convoy.

1702I/30 - The Japanese aircraft was seen for the last time.

1733I/30 - Sighted one transport and one escort bearing 123° and another transport bearing 171°. The convoy had apparently split.

1744I/30 - Changed course and headed for the nearest ship now bearing 125°.

1803I/30 - Sound reported fast screws bearing 168°. Periscope observation on that bearing revealed the tops of an escort heading back on the convoy track. It was thought this escort was deployed to pick off any surfacing submarine at sunset.

1836I/30 - Surfaced in bright moonlight. The escort, which was astern, was still heading westwards. No contacts were obtained with the SJ radar.

2024I/30 - Still no radar contact but it was thought the target could be more then 15000 yards away.

2100I/30 - Commenced a retiring search to the southward to cover the enemy's courses from 110° to 160° with a maximum expected radar range of 12000 yards. Enemy speed was estimated as being 8 knots.

[For continuation of the events see 1 February 1944.] (6)

1 Feb 1944
USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) attacked a Japanese convoy and torpedoed and sank the Japanese troop transport Toei Maru (4004 GRT, built 1937) about 175 nautical miles south of Woleai in position 04°21'N, 143°16'E.

Toei Maru was part of a convoy en-route from Palau to Rabaul. [For the composition of this convoy see the event for 30 January 1944.]

1235I/31 - Regained contact on the convoy having sighted smoke.

1250I/31 - Sighted a four-engined Japanese aircraft, thought to be a 'Mavis' (Kawanishi H6K) flying boat in the vicinity of the smoke.

1255I/31 - The sound gear reported pinging from three separate sources.

1618I/31 - Surfaced and commenced an end around.

1648I/31 - Heard distant depth charging coming from the direction of the smoke.

1710I/31 - The last depth charge, out of a total of 16, was dropped.

1716I/31 - Sighted the tops of an escort apparently conducting a search on the starboard flank of the convoy. Altered course to avoid keeping the smoke of the convoy in sight.

1810I/31 - Commenced radar tracking.

2226I/31 - USS Seahorse was now 16000 yards ahead of the convoy which was on a base course of 135° at 8 knots. Intend to maintain this position until moonset. The convoy was visible from the bridge at this range.

2300I/31 - Commenced approach. Target range was now 13750 yards. Radar had no contact on the escorts.

2314I/31 - USS Seahorse came to a stop to listen for the bearings of the escorts which were still not picked up on radar.

2321I/31 - SJ radar picked up one escort. Two other had been picked up by sound only. Continued the approach.

2344I/31 - When approaching the firing position the SJ radar malfunctioned. Broke off the attack.

2355I/31 - Radar was back in commission.

2357I/31 - Recommenced approach.

0019I/1 - In position 04°38'N, 142°49'E, fired four torpedoes from the stern tubes from 3300 yards. No hits were obtained. The target zigged away shortly after firing. All torpedoes were heard to explode at the end of their run. The convoy must now be aware of the fact it had been attacked.

0051I/1 - Commenced approach for a bow tube shoot.

0200I/1 - In position 04°32'N, 143°02'E, fired two bow torpedoes from 3100 yards. Again both missed as the target zigged away 30 seconds after firing.

0206I/1 - One torpedo was heard to explode at the end of its run. Now only two stern torpedoes were left. Decided to make a submerged radar approach.

0300I/1 - Dived. Tracked the target keeping the stern to him.

0346I/1 - Range was now 1700 yards. Came to periscope depth.

0347I/1 - The target altered course 055° to the left presenting a perfect shot however one of the escorts was very close.

0352I/1 - In position 04°21'N, 143°16'E, fired two stern torpedoes from 1000 yards. Both hit. Results were not observed as Seahorse had meanwhile gone deep.

0401I/1 - Depth charging started.

0403I/1 - A heavy explosion occurred in the target followed by a whole lot of small explosions which were thought to be ammunition and / or gasoline drums going off.

0426I/1 - Two more heavy explosions occurred in the target.

0428I/1 - Commenced coming up to periscope depth.

0430I/1 - Two distant depth charges exploded.

0443I/1 - Surfaced. The scene of the sinking was a mass of gasoline flames with drums still exploding on the surface.

0446I/1 - Opened out on the nearest escort which was at 6600 yards bearing 305°.

0538I/1 - Dived.

1705I/1 - Surfaced. Left patrol to return to Pearl Harbour. (7)

6 Feb 1944
At 1630L/6, USS Seahorse (Lt.Cdr. S.D. Cutter) received a signal from COMSUBPAC ordering her to perform a 'special operation'.

At 0430L/12, USS Seahorse (Lt.Cdr. S.D. Cutter) received a signal from COMSUBPAC releasing her from the 'special operation'.

The patrol report of USS Seahorse does not give further information but serveral night bombardments of Wake Island were carried out by PBY (Catalina) aircraft during this period. We expect USS Seahorse was deployed on air sea rescue and reconnaissance duties. (8)

16 Feb 1944
Around 1200VW/16, USS Seahorse (T/Lt.Cdr. S.D. Cutter, USN) ended her very successful third war patrol at Pearl Harbor. She was taken in hand for post patrol repairs / refit by USS Bushnell (T/Capt. C.T. Bonney, USN).

4 Mar 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) conducted exercises off Pearl Harbour.

6 Mar 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) conducted exercises off Pearl Harbour.

8 Mar 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) is docked in a floating dock at the Pearl Harbour Navy Yard.

10 Mar 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) is undocked.

12 Mar 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) is again docked in a floating dock at the Pearl Harbour Navy Yard.

14 Mar 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) is undocked.

16 Mar 1944
Around 1115VW/16, USS Seahorse (T/Cdr. S.D. Cutter, USN) departed Pearl Harbor for her fourth war patrol. She was to patrol in the Mariana Islands area.

USS Harder (T/Cdr. S.D. Dealey, USN) sailed in company.

En-route to Johnston Island some radar training exercises were carried out during which the submarines acted as target for each other. (9)

18 Mar 1944
Around 1200X/18, USS Seahorse (T/Cdr. S.D. Cutter, USN) arrived at Johnston Island to top off with fuel.

She departed to continue passage to her patrol area around 1615X/18. USS Harder (T/Cdr. S.D. Dealey, USN) was still in company.

The submarines parted company only around 1900L/26. (9)

27 Mar 1944
At 0949K/27, well east of Saipan, in position 15°15'N, 150°30'E, USS Seahorse (T/Cdr. S.D. Cutter, USN) sighted a two engined bomber, which was subsequently seen to be a 'Nell' (Mitsubishi G3M). USS Seahorse dived.

Between 0952K/27 and 0959K/27, three depth charges were dropped but none were close.

At 1701K/27, in position 15°29'N, 149°14'E, a periscope was sighted at a range of about 5000 yards 20° on the port bow. The sighting was made by the periscope which which also saw the periscope being lowered before the SJ radar could be trained on the bearing. USS Seahorse then steered various courses to the east before turning north and eventually back to the original course.

At 1724K/27, in position 15°33'N, 149°17'E, the SJ radar obtained a contact bearing 257°, range 5150 yards.

At 1736K/27, the periscope watch sighted a periscope bearing 245°. About eight feet of periscope was exposed by the supposed enemy submarine.

The following Japanese submarines may have been passing through this area;
I-16 had departed Yokusuka for Truk on 17 March.
I-176 had departed Truk for Sasebo on 23 March.
I-185 had departed Kure for Mili (Marshall Islands) on 20 March (all offsite links). (10)

3 Apr 1944
At 0900K/3, south-west of Tinian, in position 14°41'N, 145°18'E, USS Seahorse (T/Cdr. S.D. Cutter, USN) picked up the HE bearing 010°. A Japanese Mutsuki-class destroyer was subsequently seen bearing 000° at a range of about 8000 yards. The destroyer was making revs. for 18 knots and was zigzagging radically. It was not possible to close to attack. (9)

5 Apr 1944
At 1245K/5, north-east of Saipan, in position 15°20'N, 145°38'E, USS Seahorse (T/Cdr. S.D. Cutter, USN) sighed and avoided a small sampan.

At 1429K/5, east of Saipan, in position 15°13'N, 145°37'E, USS Seahorse sighted the tops of a convoy bearing 180°. Range was about 20000 yards. An hours later the convoy was seen to enter Tanapag harbour. The convoy was made up of several transports and several escorts [No further details given].

The convoy sighted came from Palau and was made up of the tankers Kyoei Maru (591 GRT, built 1937), Yuho Maru (5227 GRT, built 1943), munitions transport Aratama Maru (6784 GRT, built 1938), transports Kizugawa Maru (1915 GRT, built 1941) and Matsue Maru (7061 GRT, built 1921). They were escorted by the destroyers Minazuki, Yuzuki, submarine chaser Ch-30 and the auxiliary submarine chasers Kyo Maru No.7 (341 GRT, built 1937) and Takunan Maru No.2 (343 GRT, built 1937) (all links are offsite links). (9)

8 Apr 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) attacked a Japanese convoy and torpedoed the munitions transport Aratama Maru (6784 GRT, built 1938) and the transport Kizugawa Maru (1915 GRT, built 1941) off Guam in position 13°16'N, 145°11'E. The explosion on Aratama Maru damaged the Japanese destroyer Asakaze (offsite link). The burning Aratama Maru is beached on Guam but explodes and sank the next day. The damaged Kizugawa Maru is towed into harbour at Guam by the destroyer Minazuki (offsite link). Both destroyers had been the escort of the convoy which had been bound for Woleai, Caroline Islands. (all links are offsite links).

1404K/7 - Heard pinging bearing 004°. Commenced to close.

1530K/7 - In position 14°35'N, 145°35'E, sighted a convoy made up of three transports escorted by two destroyers. Air cover was patrolling over the convoy.

1928K/7 - Surfaced and found the visibility to be excellent with a full moon and clear sky.

1941K/7 - Obtained radar contact bearing 210° at 27000 yards. Commenced an end around run tracking the convoy at ranges between 32000 and 36000 yards to avoid probable air cover. The SJ radar was working perfectly.

0100K/8 - Dived 23500 yards ahead of the convoy.

0216K/8 - Passed between the destroyer screen at ranges of 900 and 1800 yards respectively. Both escorts were echo ranging on the bow of the convoy.

0219K/8 - The leading ship in the port column of the convoy was now dead ahead at a range of about 2000 yards angle on the bow 10° starboard when the ships made a wide zig to starboard.

0221K/8 - Angle on the bow of the first target was now 30° port, range 1200 yards. Commenced firing three torpedoes without waiting for a more favourable setup. The second target would soon be blanked off by the first so commenced firing three torpedoes at it as well, angle on the bow 50° port, range 2200 yards. Position of firing was to the west of Guam in 13°16'N, 144°55'E.

0222K/8 - Three hits were obtained on the first target.

0224K/8 - Saw the second target being hit by a torpedo. The first target had meanwhile exploded, most likely having carried ammunition as only a pall of smoke was seen where it had been. The second target was on fire amidships but on an even keel and not low in the water. Sound reported that the destroyers were coming in so went deep.

Depth charging commenced. A total of 28 were counted but none were close.

0525K/8 - Surfaced. Range to the target was 13200 yards. It was now completely engulfed in flames with frequent violent explosions emitting from the inferno. The only parts visible were the two masts, two sets of goalposts and the superstructure. The ship had a large list to port and was low in the water.

0543K/8 - Dived.

9 Apr 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) torpedoed and heavily damaged the Japanese transport Mimasaka Maru (4667 GRT, built 1944) about 40 nautical miles west of Saipan in position 15°22'N, 145°06'E. The ship was taken in tow but sank later.

Mimasaka Maru was in a large convoy coming from Tokyo which was further made up of the fleet supply ships Kinezaki (754 GRT, built 1940), Mamiya (15820 GRT, built 1923), transports Akikawa Maru (5244 GRT, built 1943), Azuchisan Maru (6888 GRT, built 1944), Havre Maru (5821 GRT, built 1920), Koko Maru (1510 GRT, built 1922), Kokogawa Maru (6886 GRT, built 1944), Macassar Maru (4026 GRT, built 1920), Nisshu Maru (5948 GRT, built 1917), Shima Maru (1976 GRT, built 1920), Shinsei Maru (2880 GRT, built 1944), Shinsei Maru No.5 (2712 GRT, built 1919), Shinyo Maru (4737 GRT, built 1918), Shiramine Maru (2857 GRT, built 1944), Shoun Maru (4396 GRT, built 1941), Shozui Maru (2719 GRT, built 1940), Taian Maru (5492 GRT, built 1921), Taikai Maru (2508 GRT, built 1919), Takasan Maru (1428 GRT, built 1943), Tatebe Maru (4519 GRT, built 1942), Tenryugawa Maru (3883 GRT, built 1941), Toan Maru (2110 GRT, built 1943), Toko Maru (4176 GRT, built 1908) and Unyo Maru No.8 (1942 GRT, built 1944). They were escorted by the destroyers Samidare, Asanagi, torpedo boat Hiyodori, frigates Amakusa, Fukue, Oki, Mikura, Kaibokan 2, Kaibokan 3 and the submarine chaser CH 50 (all links are offsite links).

1521K/9 - To the west-north-west of Saipan, in position 15°33'N, 144°52'E, sighted smoke bearing 330°. Assumed this to be the expected convoy and that it was making for Tanapag harbour. Commenced to close at high submerged speed. Two aircraft were seen to be patrolling over the convoy. The convoy was very large, about 15 to 20 transports with at least 4 destroyers and many other escorts. A large transport on the starboard flank of the convoy was selected as target and an attack was started.

1726K/9 - In position 15°22'N, 145°06'E commenced firing six bow torpedoes from 1800 yards. The first four were fired before the target changed course and the torpedoes thus missed. One was running erratically and passed close aboard the submarine several times. A new setup was then made and at 1729K/9 the remaining two bow torpedoes were fired which both hit. USS Seahorse went deep after firing.

1733K/9 - Depth charging started and some were close.

1735K/9 - The target was heard to be breaking up with numerous small explosions.

1740K/9 - The escorts lost contact. USS Seahorse set course to clear the area to the northwest.

1945K/9 - Returned to periscope depth. The target was still in sight and was seen to be well down by the stern. Two destroyers were standing by.

2118K/9 - Surfaced for a much needed battery charge. Range to the target was 18550 yards.

2125K/9 - Heavy radar interference. The radar operators were able to get good bearings on the source of the interference.

2130K/9 - In position 15°30'N, 144°49'E, obtained radar contact in the direction of the enemy radar interference at a range of 15000 yards. The enemy radar was sweeping across USS Seahorse every 15 seconds. The range closed to 11000 yards and the contact was then identified as two large destroyers which was making 20 knots steering various courses to the north-east. Contact was lost shortly afterwards.

2151K/9 - An aircraft was sighted patrolling the area for which USS Seahorse had to dive. Later also a destroyer was seen conducting a high speed search in the area. The closest this destroyer came was 5000 yards. It was thought that the Japanese thought the submarine had not surfaced yet following the attack and were trying to keep it down during the night.

0120K/10 - Surfaced.

0124K/10 - Changed course to head for the target at slow speed while charging batteries.

0227K/10 - Plane contact by sight and radar at a range of 14000 yards. Dived.

0241K/10 - Surfaced and continued heading towards the targets position.

0337K/10 - Obtained a radar contact at 10000 yards. Shortly afterwards sighted a destroyer closing fast with a small angle on the bow.

0339K/10 - Dived as the range had closed to 8800 yards. Observed the destroyer patrolling at high speed through the periscope.

0410K/10 - Surfaced and continued towards the position of the target.

0419K/10 - Sighted a destroyer to the west, radar gave a range of 12000 yards.

0425K/10 - Sighed a destroyer to the east, radar gave a range of 14500 yards.

0427K/10 - Obtained a radar contact on two approaching aircraft. Dived.

0452K/10 - Came to radar depth. Two aircraft were picked up on radar. It was thought these aircraft were patrolling near yesterdays attack position. Changed course to close.

0600K/10 - The aircraft left the area proceeding to the north-west followed by the destroyers.

0837K/10 - Saw a whole lot of wreckage floating on the surface.

1912K/10 - Surfaced.

2124K/10 - Dived for an aircraft passing close ahead from port to starboard.

2150K/10 - Surfaced.

2248K/10 - Obtained a radar contact at a range of 14000 yards bearing 253°. Sighted a destroyer turning towards shortly afterwards.

2255K/10 - Dived. Range was now 9850 yards. Tracked the destroyer at 18 knots. Closest range was 6000 yards and it became apparent that the turn towards was just a normal leg of this destroyers search plan.

2331K/10 - Decided to open out to patrol the shipping lanes to the west of Saipan as this area is very heavily patrolled by the enemy. (10)

15 Apr 1944
At 0800K/15, north-west of Saipan, in position 15°22'N, 145°39'E, USS Seahorse (T/Cdr. S.D. Cutter, USN), heard pinging and commenced to close Tanapag harbour.

At 0810K/15, smoke was sighted from ships leaving Tanapag Harbour via the north passage. It was not possible to reach a firing position so a course was set to run parallel to the convoy at 5 knots submerged hoping to maintain contact and attack at night. The tops of two large transports were seen and echo ranging was heard from two sources. The closest range to the convoy was 20000 yards. Course of the convoy was 010° at a speed of 8 knots.

At 1353K/15, USS Seahorse surfaced to charge the depleted battery and close the convoy. Air escort was in sight continuously. By running at 10 knots USS Seahorse left very little wake and the planes did not sight the submarine. Two sampans were seen in position 15°47'N, 145°42'E at ranges of 6500 and 9000 yards. Neither showed signs of having sighted the submarine.

At 1422K/15, USS Seahorse had to dive as a 'Davis aircraft' came toward instead of circling back to the convoy as he had done before. The aircraft continued in after the submarine had dived but shortly afterwards the enemy turned back towards the convoy.

At 1604K/15, USS Seahorse surfaced for another battery charge. The two sampans were still in sight. Visibility soon decreased somewhat making it impossible to observe the enemy aircraft. Rain squalls were in the vicinity and the sky was about 75% overcast.

At 1647K/15, USS Seahorse dived for an aircraft contact on the SJ radar at a range of 30000 yards. Sight contact of the smoke of the convoy had been regained and it was noted that the base course of the convoy was now 340° passing between Anathan and Sarigan Islands. The aircraft was not sighted after USS Seahorse had submerged and it was not thought she had been sighted.

At 1917K/15, USS Seahorse surfaced and set off in pursuit of the convoy.

At 2030K/15, in position 16°29'N, 145°44'E, two patrol vessels were detected proceeding northwards at 14 knots. Contact with the convoy was meanwhile lost and could not be regained.

The ships sighed were most likely ships of a convoy that departed Saipan for Tokyo. It was made up of the transports Kokogawa Maru (6886 GRT, built 1944), Macassar Maru (4026 GRT, built 1920), Nisshu Maru (5948 GRT, built 1917), Shiramine Maru (2857 GRT, built 1944), Takasan Maru (1428 GRT, built 1943), Toko Maru (4176 GRT, built 1908), Unyo Maru No.8 (1942 GRT, built 1944) and one other transport. They were escorted by the destroyer Asanagi, torpedo boat Hiyodori and the submarine chaser CH 50 (all links are offsite links). (10)

17 Apr 1944
At 1415K/17, USS Seahorse (T/Cdr. S.D. Cutter, USN) examined Tanapag harbour. It was found to be relatively empty and ships must have left harbour when USS Seahorse was away chasing the convoy. A Japanese light cruiser was seen inside the harbour as were a large tanker and several transports. The cruiser must have been the Kinu which had arrived at Saipan that day.

The following day the harbour was examined again and it was seen that the same ships were still present. (10)

20 Apr 1944
There is a claim that USS Seahorse (T/Cdr. S.D. Cutter, USN) torpedoed and sank a Japanese submarine to the north-west of Saipan in position 15°19'N, 145°30'E. This was thought to have been RO-45 (offsite link) but this is not the case as RO-45 was active after this date. She had departed Kure for Truk on 16 April making it highly unlikely that she was already in the Saipan area on this day.

The Japanese submarines RO-109 and RO-112 both arrived at Saipan on this day and most likely one of them had been the target. The torpedo explosion heard may have been a premature torpedo explosion.

1007K/20 - in position 15°19'N, 145°30'E, sighed a Japanese Ro-type submarine bearing 210°. The bow wave of the enemy indicated a moderate speed. The turn count gave a speed of 10 knots. The enemy was steering a constant helm zig plan. Mean course was about 097°.

1021K/20 - Fired two torpedoes from 1675 yards. A very loud torpedo explosion was heard and felt. It is thought an explosion in the target also occurred. The result was not observed as depth control had been lost.

Oil was later seen in the area of the attack. (11)

21 Apr 1944
At 0622K/21, in position 15°18'N, 145°28'E, USS Seahorse (T/Cdr. S.D. Cutter, USN) sighed another Japanse RO-class submarine bearing 251° at a range of about 6000 yards. Commenced a high speed submerged approach but the distance could not be closed sufficiently to make an attack. This submarine looked like the same general construction as the one seen yesterday but had an open bridge aft. Enemy course was 160° at 9.5 knots. (9)

22 Apr 1944
At 0907K/22, USS Seahorse (T/Cdr. S.D. Cutter, USN) picked up pinging bearing 130°. Commenced to close.

At 0917K/22, to the west of Saipan, in position 15°14'N, 145°38'E, USS Seahorse sighted a large transport and an escort at a range of 11000 yards. A few minutes later the target made a large alteration of course to the right and the range could not be closed further than to 9000 yards. Enemy course was now 332° making 11.5 knots.

At 1255K/22, a convoy made up of four small inter island transports of about 1500 tons was sighted bearing 040° at a range of 7000 yards in position 15°27'N, 145°29'E. They were not escorted and proceeding on course 135° at 6 knots. Decided to continue to trail the escorted large transport.

At 1354K/22, USS Seahorse surfaced in pursuit of the large transport.

At 0644K/23, the search for the large escorted transport was broken off and course was set to return to Saipan. (9)

25 Apr 1944
At 1148K/25, north-west of Saipan, in position 15°57'N, 145°19'E, USS Seahorse (T/Cdr. S.D. Cutter, USN) sighed two trawler type vessels beering 355° at a range of about 9000 yards. USS Seahorse closed and looked them over but they were considered to be too small for a torpedo attack. Both were loaded with cargo and were zigzagging on a base course of 130° obviously heading for Saipan. (9)

27 Apr 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) attacked a Japanese convoy and torpedoed and sank the Japanese transport Akikawa Maru (5244 GRT, built 1943) about 150 nautical miles west of Saipan in position 14°46'N, 143°22'E.

0940K/26 - west of Saipan, in position 15°13'N, 145°20'E, sighted smoke bearing 093° which developed into a convoy of three large transports, a small transport escorted by a destroyer and three smaller escort vessels. The convoy was making slow speed and it was intended to maintain contact during daylight and attack after dark.

1927K/26 - Surfaced.

2015K/26 - Obtained radar contact bearing 267°, range 21850 yards.

2327K/26 - USS Seahorse was now dead ahead of the convoy. Light conditions were unsuitable for a surface attack.

0030K/27 - Dived for a submerged attack and headed in towards the convoy. All escorts were heard to be pinging. Only two torpedoes were in the forward tubes and as all aft tubes were loaded decided to make a stern tube attack.

0115K/27 - One of the escorts obtained contact on USS Seahorse and it was seen close aboard so quickly fired four stern torpedoes at the largest transport from 1300 yards. Three hits were observed before USS Seahorse went deep. It could just be seen that the target was settling by the stern.

0243K/27 - Came to radar depth and obtained contact on an escort at about 6000 yards. As USS Seahorse came up to periscope depth two depth charges exploded followed by another one that rocketed the submarine. The radar operator then obtained another radar contact at only 1100 yard. USS Seahorse quickly went deep.

0315K/27 - Started to get back up to radar depth.

0337K/27 - Surfaced. No radar contacts were obtained. Course was set to leave the Saipan area to proceed to Satawan Atoll to the south-east of Truk where lifeguard rescue duties were to be performed during an upcoming air strike.

29 Apr 1944
At 0820K/29, north-east of Truk, in position 09°24'N, 153°45'E, USS Seahorse (T/Cdr. S.D. Cutter, USN) was caught on the surface by a US Liberator aircraft which dropped two bombs from 200 feet which caused no damage. USS Seahorse was attacked in an area where allied aircraft were not allowed to attack submarines. (9)

30 Apr 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) arrived off the Satawan Atoll for lifeguard duties. (9)

30 Apr 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) conducted air-sea rescue (lifeguard) duties during air and bombardment operations by Task Force 58 off the Satawan Atoll.

[Note: Task Force 58 (time zone Y) and USS Seahorse (time zone K) kept different time zones thus on board USS Seahorse the date was 1 May 1944.]

USS Seahorse departed her lifeguard station at 2017K/3 when course was set for Milne Bay, New Guinea. (9)

5 May 1944
At 1450K/5, near Manus, USS Seahorse (T/Cdr. S.D. Cutter, USN) was joined by USS Bowers (T/Lt.Cdr. F.W. Hawes, USN).

They remained in company until 1130K/6. (12)

7 May 1944
At 1441K/7, USS Seahorse (T/Cdr. S.D. Cutter, USN) arrived at Milne Bay. (9)

8 May 1944
At 0700K/8, USS Seahorse (T/Cdr. S.D. Cutter, USN) departed Milne Bay for Brisbane, Australia. (9)

11 May 1944
Around 0930K/11, USS Seahorse (Lt.Cdr. S.D. Cutter) ended her fourth war patrol at Brisbane, Australia.

3 Jun 1944
Around 1400K/3, USS Seahorse (T/Cdr. S.D. Cutter, USN) departed Brisbane, Australia for her fifth war patrol. She was ordered to patrol in the Luzon Strait between Formosa and Luzon.

Before proceeding to her patrol area she was to top off with fuel at Seeadler Harbour, Manus, Admiralty Islands. (13)

9 Jun 1944
Around 0550K/9, USS Seahorse (T/Cdr. S.D. Cutter, USN) is joined by USS PC-1134 (Lt. D.J. Callaghan. Jr. USNR).

They parted company around 1350K/9. (14)

10 Jun 1944
Around 1400K/10, USS Seahorse (T/Cdr. S.D. Cutter, USN) arrived at Seeadler Harbour, Manus, Admiralty Islands from Brisbane.

Some minor voyage repairs were made by USS Euryale (T/Capt. H.A. Guthrie, USN). (13)

11 Jun 1944
Around 1500K/11, USS Seahorse (T/Cdr. S.D. Cutter, USN) departed Seeadler Harbour, Manus, Admiralty Islands to proceed to her patrol area. (13)

15 Jun 1944
At 1845K/15, USS Seahorse (T/Cdr. S.D. Cutter, USN), east of Mindanao, in position 09°30'N, 128°49'E, the periscope watch sighted smoke bearing 337°. USS Seahorse closed and the tops of four large men-of-war were seen at an estimated range of 19 nautical miles. Six other sources of smoke were in sight.

At 1855K/15, contact was lost in the growing darkness.

At 1936K/15, Obtained radar contact on three ships bearing 031° at a range of 27000 yards. Commenced tracking at maximum speed. Tracking revealed six large ships and two smaller ones on a base course of 045° at 16.5 knots zigging 20° either side of their base course. USS Seahorse was on their starboard flank and the minimum range obtained on the starboard screening vessel was 19000 yards.

2300K/15, Speed limitations imposed by main motor sparking made it impossible to reach an attack position so commenced sending a contact report.

0000K/15, Main motor sparking became so bad that speed had to be reduced to 14.5 knots. Contact was lost soon afterwards.

0300K/15, Cleared contact report after much difficulty had been experienced due to very persistent jamming by the enemy.

0535K/15, Dived to effect repairs to the main motors.

The Japanese force encountered by USS Seahorse was made up of the battleships Yamato, Musashi, heavy cruisers Haguro, Myoko, light cruiser Noshiro and the destroyers Asagumo, Shimakaze and Okinami (all links are offsite links). (15)

22 Jun 1944
At 0713I/22, USS Seahorse (T/Cdr. S.D. Cutter, USN) received a signal ordering her to make rendezvous with USS Bang (T/Cdr. A.R. Gallaher, USN) and USS Growler (T/Cdr. T.B. Oakley, Jr., USN) and operate as a coordinated attack group. (13)

24 Jun 1944
At 0255H/24, USS Seahorse (T/Cdr. S.D. Cutter, USN) made rendezvous with USS Growler (T/Cdr. T.B. Oakley, Jr., USN). They then proceeded in company to around 0700H/24 when both dived to continue independently to their rendezvous with USS Bang (T/Cdr. A.R. Gallaher, USN).

USS Seahorse arrived at the rendezvous around 2035H/24 and calls were exchanged with USS Growler around 0015H/24. USS Bang did not show up at the rendezvous.

USS Seahorse made contact with USS Bang shortly after 2000H/25. Cdr. Cutter then went aboard USS Bang for patrol instructions. They parted company around 2325H/25. (13)

27 Jun 1944
USS Seahorse (T/Cdr. S.D. Cutter, USN) attacked a Japanese convoy and torpedoed and sank the tanker Medan Maru (5136 GRT, built 1943) south of Formosa in position 21°10'N, 120°31'E.

0050H/27 - Obtained radar contact bearing 243° at a range of 29000 yards. First estimation of the enemy's course was 150°. Set course to get ahead of the contact and prepared a contact report for USS Bang (T/Cdr. A.R. Gallaher, USN) and USS Growler (T/Cdr. T.B. Oakley, Jr., USN).

0110H/27 - Tracking showed the convoy to be on a northwest course at 12 knots. As USS Bang, the closest of the other two submarines of the wolf pack, was 40 miles away and she would not be able to intercept this convoy no contact report was sent. The convoy was constant helming at half an hour legs of a wild zig plan. Base course was found to be 340°. Proceeded to a position ahead of the convoy and then track while deciding for the best way to attack. Ten ships were counted, five believed to be merchant vessels and five believed to be escorts.

0358H/27 - Dived for a submerged attack from periscope depth.

0412H/27 - In position 21°21'N, 120°18'E, fired two bow torpedoes at a 4000 tons transpor, closely grouped together with two other transports, from 2450 yards followed by four at a 10000 tons tanker from 950 yards.

Five hits were obtained, three on the tanker, one on the transport which was the intended target and one on another transport, also around 4000 tons. Both transports were seen to come to a stop and the tanker was a mass of flames.

0415H/27 - Depth charging started which lasted for five minutes. One of the escorts however continued to search near the position of USS Seahorse.

3 Jul 1944
During the night of 3 / 4 July 1944 USS Seahorse (Lt.Cdr. S.D. Cutter) torpedoed and sank the Japanese merchants Gyoyu Maru (2232 GRT), Niito Maru (2186 GRT) and Kyodo Maru No.28 (1518 GRT) in the South China Sea about 140 nautical miles south of Hong Kong in position 20°18'N, 115°02'E.

19 Jul 1944
USS Seahorse (Lt.Cdr. S.D. Cutter) ended her 5th war patrol at Pearl Harbor.

10 Aug 1944
During 10/11 August 1944, USS Skipjack (T/Cdr. R.S. Andrews, USN) and USS Searaven (T/Cdr. M.H. Dry, USN) conducted exercises off Pearl Harbour with USS Burden R. Hastings (Lt.Cdr. E.B. Fay, USNR).

Later USS Seahorse (T/Capt. C.W. Wilkins, USN) and USS Allen (Lt. W.J. Riley, Jr., USNR) before the night exercises commenced.

On the 11th, USS Greiner (T/Lt.Cdr. L.H. Kiser, USN) also joined. (16)

6 Oct 1944
While on her 6th war patrol USS Seahorse (Lt.Cdr. Charles Warren Wilkins) torpedoed and sank the Japanese Coast Defense Vessel Kaibokan 21 (745 tons, offsite link) about 140 nautical miles North-West of Cape Bojeador, Luzon in position 19°27'N, 118°08'E.

18 Oct 1944
USS Seahorse (Lt.Cdr. C.W. Wilkins) ended her 6th war patrol at Midway. She was ordered to the Mare Island Navy Yard for overhaul.

5 Mar 1945
USS Bullhead (Cdr. W.T. Griffith, USN) conducted exercises off Pearl Harbour together with USS Pruitt (Lt. D.B. Harby, USNR), USS YMS-300 (Lt. R.A. Woods, USNR) and USS Seahorse (Cdr. H.H. Greer, Jr., USN).

9 Mar 1945
USS Seahorse (Cmdr Harry Holt Greer, Jr.) left base for her 7th war patrol, and was ordered to patrol the Tsushima Strait.

9 Apr 1945
USS Seahorse (Cdr. H.H. Greer, Jr) sank a small junk with gunfire in position 33°20'N, 127°36'E.

18 Apr 1945
USS Seahorse (Cdr. H.H. Greer, Jr) is damaged by depth charges in Tsushima Strait in position 33°45'N, 128°26'E and is forced to terminate her patrol.

12 Jul 1945
After repairs and overhaul USS Seahorse (Cdr. H.H. Greer, Jr) left Pearl Harbor for her 8th war patrol. She was to patrol of the Izu Islands, Japan. When the war ended on 15 August 1945 Seahorse was on patrol 40 miles southeast of Hachijo Shima. She returned to Midway in the latter half of August.

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