Japanese Subchasers

KUSENTEI!

IJN Subchaser CH-31: Tabular Record of Movement
© 2005-2017 Bob Hackett, Sander Kingsepp and Peter Cundall
Revision 11

1941:
Tokyo. Laid down at the Ishikawajima shipyard.
7 March 1942:
Launched and numbered CH-31.
15 June 1942:
Completed and registered in the Yokosuka Naval District.
4 July 1942:
At 0600 departs Truk with minelayer TSUGARU escorting NOJIMA MARU.
7 July 1942:
At 1730 arrives at Lae. TSUGARU departs soon after at 2100 back to Truk.
8 July 1942:
NOJIMA MARU and CH-31 depart Lae.
9 July 1942:
Arrives at Rabaul.
14 July 1942:
Assigned to the 8th Base Force at Rabaul in Vice Admiral Mikawa Gunichi's (38)(former CO of KIRISHIMA) newly formed 8th Fleet.
17 July 1942:
At 1615 departs Rabaul on escort duties.
20 July 1942:
At 0500 arrives at Rabaul.
23 July 1942:
At 2300 departs Rabaul on escort duties.
28 July 1942:
At 1300 arrives back at Rabaul.
2 August 1942:
At 1700 departs Rabaul on escort duties.
6 August 1942:
At 1040 arrives back at Rabaul.
7 August 1942:
At 1030 departs Rabaul on short patrol.
8 August 1942:
At 1215 arrives back at Rabaul.
9 August 1942:
At 0640 departs Rabaul on escort duties.
11 August 1942:
Arrives at Kavieng.
12 August 1942:
Departs Kavieng.
13 August 1942:
At 0530 returns to Rabaul.
14 August 1942:
At 1000 departs Rabaul to Truk for repairs.
18 August 1942:
Arrives at Truk.
22 August 1942:
At 1130 departs Truk escorting Naval transport HINO MARU No. 3.
23 August 1942:
At 1130 detaches from HINO MARU No. 3 and returns to Truk.
24 August 1942:
Arrives at Truk.
26 August 1942:
Participates in capture of Nauru, Gilbert (now Kiribati) Islands. Departs Truk.
September 1942:
Arrives back at Rabaul.
1 October 1942:
At 1645 departs Rabaul on patrol.
3 October 1942:
At 0510 arrives back at Rabaul.
6 October 1942:
At 0630 departs Rabaul on patrol.
10 October 1942:
At 0730 arrives back at Rabaul.
11 October 1942:
At 1300 departs Rabaul on patrol.
17 October 1942:
At 0840 arrives at Rabaul. At 2130 departs again on patrol.
20 October 1942:
At 1040 arrives at Rabaul. At 2300 departs again on patrol.
24 October 1942:
At 0400 arrives back at Rabaul. Later that day CH-31 and CH-32 are bombed and damaged by USAAF Boeing B-17 "Flying Fortresses". At an unknown date departs Rabaul to return to Japan for repairs.
13 November 1942:
At 0400 arrives at Yokosuka. Undergoes bomb-damage repairs over the next few weeks.
8 December 1942:
At 1400 arrivres at Truk on an escort mission.
14 December 1942:
At 1500 departs Truk on an escort mission, probably to Rabaul.
11 January 1943:
At 0720 arrives back at Rabaul.
13 January 1943:
At 0700 departs Rabaul on patrol.
14 January 1943:
At 1600 arrives back at Rabaul.
16 January 1943:
At 0805 departs Rabaul on patrol.
18 January 1943:
At 0850 arrives back at Rabaul.
19 January 1943:
At 0700 departs Rabaul on patrol.
20 January 1943:
At 0900 arrives back at Rabaul.
22 January 1943:
At 0630 departs Rabaul on patrol.
23 January 1943:
At 0900 arrives back at Rabaul.
25 January 1943:
At 1000 departs Rabaul on patrol.
26 January 1943:
At 1000 arrives back at Rabaul.
30 January 1943:
At 0600 departs Rabaul on patrol.
31 January 1943:
At 0800 arrives back at Rabaul.
1 February 1943:
At 0630 departs Rabaul on patrol.
3 February 1943:
At 0815 arrives back at Rabaul.
5 February 1943:
At 0620 departs Rabaul on patrol.
7 February 1943:
At 0830 arrives back at Rabaul.
9 February 1943:
At 1530 departs Rabaul on patrol.
11 February 1943:
At 0800 arrives back at Rabaul.
13 February 1943:
At 1630 departs Rabaul on patrol.
15 February 1943:
At 0800 arrives back at Rabaul.
17 February 1943:
At 0800 departs Rabaul on patrol.
18 February 1943:
At 0900 arrives back at Rabaul.
19 February 1943:
At 0630 departs Rabaul on patrol.
20 February 1943:
At 0430 arrives back at Rabaul.
22 February 1943:
At 0640 departs Rabaul on patrol.
24 February 1943:
At 1020 arrives back at Rabaul.
25 February 1943:
At 0800 departs Rabaul on patrol.
27 February 1943:
At 0750 arrives back at Rabaul.
28 February 1943:
At 0600 departs Rabaul on patrol.
1 March 1943:
At 0830 arrives back at Rabaul. Reassigned to the Fourth Fleet's 4th Base Force at Truk but remains based at Rabaul for time being. At 2200 departs Rabaul on escort mission.
3 March 1943:
At 1010 arrives back at Rabaul.
7 March 1943:
At 0400 departs Rabaul on an escort mission.
10 March 1943:
CH-31 departs Kavieng, New Ireland escorting NISSHUN MARU (unconfirmed) to the latitude of the Equator and returns to Kavieng.
13 March 1943:
At 0640 arrives back at Rabaul.
15 March 1943:
At 1630 departs Rabaul on escort mission.
Mid-March 1943:
CH-31 departs Kavieng for Rabaul escorting aircraft ferry MOGAMIGAWA MARU.
23 March 1943:
At 0630 arrives back at Rabaul.
26 March 1943:
At 1400 departs Rabaul on an escort mission to Truk.
30 March 1943:
At 0500 arrives off Truk and enters lagoon at 1700. From this date based out of Truk.
2 April 1943:
At 1700 escorts into Truk a convoy from Rabaul.
5 April 1943:
At 1300 departs Truk on an escort mission.
7 April 1943:
At 1600 arrives back at Truk.
10 April 1943:
At 0745 departs Truk on an anti submarine patrol.
12 April 1943:
At 1050 arrives back at Truk.
13 April 1943:
At 1500 departs Truk escorting a convoy to Palau consisting of MUKO and FUKUYAMA MARUs and possibly others.
18 April 1943:
At 1630 arrives at Palau.
22 April 1943:
At 1400 departs Palau escorting a convoy to Truk.
28 April 1943:
At 0600 arrives at Truk.
2 May 1943:
At 0700 departs Truk escorting KUMAGAWA MARU.
3 May 1943:
At 1800 arrives at Ponape.
4 May 1943:
At 1500, CH-31 departs Ponape escorting KUMAGAWA MARU.
6 May 1943:
At 0600 arrives at Truk.
7 May 1943:
At 0630 departs Truk on an anti submarine sweep.
8 May 1943:
At 1430 arrives back at Truk.
11 May 1943:
At 1330 departs Truk with minesweeper W-8 escorting convoy No. 5113 consisting of YAMAKUNI, ASAYAMA (CHOZAN) and OKITSU MARUs.
16 May 1943:
At 1100 arrives at Kwajalein.
20 May 1943:
At 0600 transfers from Kwajalein to nearby Roi (Ruotto).
21 May 1943:
At 0610 departs Roi with the destroyer OITE and auxiliary sub chaser TAMA MARU No. 5 escorting OKITSU MARU towing the damaged tanker IRO.
23 May 1943:
Departs Jaluit. At some point TAMA MARU No. 5 is detached.
E 30 May 1943:
The convoy arrives at Saipan, Marianas.
1 June 1943:
The convoy departs Saipan for Kure with auxiliary netlayer SHUKO MARU as an additional escort that returns to Saipan the following day.
10 June 1943:
SE of Fuka Island, Oita Ken. At about 0500, IRO, still under tow, is hit by two of four torpedoes fired by LtCdr (later Rear Admiral) Lawrence R. Daspit's' (USNA ’27) USS TINOSA (SS-283) at 31-14N, 132-44E. IRO sustains some flooding , but continues under tow.
Auxiliary minesweepers TAKUNAN MARU No. 3 and TAKUNAN MARU No. 8 join as additional escorts at 31-52N, 132-25E.
11 June 1943:
At 1530 arrives at Kure, the others following the following day.
23 June 1943:
At 0630 departs Kure for Saeki.
26 June 1943:
At 0800, CH-31 departs Saeki with patrol boat PB-31 escorting convoy O-503 consisting of NICHIZUI, TATSUMIYA and HAVRE MARUs.
5 July 1943:
At 0800 arrives at Palau.
8 July 1943:
At 1200 departs Palau on an escort mission.
11 July 1943:
At 1400 arrives at Truk.
14 July 1943:
At 1400 departs Truk on an anti submarine sweep.
15 July 1943:
At 1710 arrives back at Truk.
21 July 1943:
At 0530 departs Truk.
22 July 1943:
At 1810 arrives at Jaluit.
24 July 1943:
At 1400 departs Jaluit.
25 July 1943:
At 0720 arrives at Mille.
26 July 1943:
At 1400 departs Mille.
28 July 1943:
At 0630 arrives at Tarawa.
31 July 1943:
At 0600 departs Tarawa.
3 August 1943:
Returns to Tarawa.
5 August 1943:
Departs Tarawa.
6 August 1943:
Arrives at Kwajalein.
9 August 1943:
Departs Kwajalein on an escort mission.
14 August 1943:
Arrives back at Kwajalein.
15 August 1943:
Reassigned to Marshalls area Butai.
1 September 1943:
At 0500 departs Kwajalein.
5 September 1943:
At 0545 arrives at Otorishima (Wake Island) and departs later that day at 1450.
9 September 1943:
At 1345 arrives at Kwajalein.
11 September 1943:
At 1200 CH-31 departs Kwajalein with auxiliary subchaser CHa-46 and possibly auxiliary subchaser CHa-16 escorting convoy No. 6113 consisting of fleet oiler SHIRETOKO, cargo ships CHIHAYA, KATORI and FUJIKAWA MARUs and possibly others.
12 September 1943:
Alerted by an Ultra signal, LtCdr (later Cdr) Carter L. Bennett's (USNA ’33) USS PERMIT (SS-178) intercepts the convoy. Bennett sets up and fires six torpedoes at three ships in submerged night attacks. He hits and damages FUJIKAWA MARU at 08-33N, 165-12E. Later, she is towed back to Kwajalein by CHIHAYA MARU. Soon after, in a second attack, USS PERMIT gets two hits on SHIRETOKO. That same day, light cruiser NAKA departs Truk to assist the torpedoed ships.
13 September 1943:
In the morning, Bennett continues his attack on the convoy. He fires three torpedoes at SHIRETOKO and claims three hits. Bennett last sees her low in the water. Later, she is taken in tow by KATORI MARU.
15 September 1943:
At 1300, USN codebreakers intercept and decrypt a message from ComCruDiv14 that reads: "NAKA, subchaser 31, Minesweeper 16, [auxiliary] subchaser 46, KATORI MARU arrived Roi, (escorting KATORI MARU towing SHIRETOKO.)”. At 1000 CH-31 arrives at Roi.

18 September 1943:
At 0330 CH-31 departs Kwajalein with CH-28, auxiliary subchasers KYO MARU No. 6 and TAKUNAN MARU No. 10 and torpedo boat HIYODORI escorting convoy 6188 consisting of KEMBU, CHIHAYA, MINATO, TSUNESHIMA, SHIGANOURA, MUKO and KENRYU MARUs.
25 September 1943:
At 1200 arrives at Truk.
30 September 1943:
At 1000, CH-31 departs Truk with auxiliary subchasers KYO MARU No. 6 and CHa-18 escorting convoy No. 5291 consisting of MATSUTAN (SHOTAN) and SEIKAI MARUs bound for Kwajalein.
6 October 1943:
At 0800 arrives at Kwajalein.
19 October 1943:
At 0300 departs Kwajalein.
20 October 1943:
At 1350 arrives ar Maloelap.
22 October 1943:
Departs Maloelap.
23 October 1943:
Arrives at Kwajalein.
1 November 1943:
CH-31 departs Roi, Kwajalein with torpedo boat HIYODORI, and auxiliary subchaser CHa-6 escorting damaged fleet oiler SHIRETOKO under tow by MOMOGAWA MARU in a convoy for Sasebo via Truk consisting of small cargo ships TAKUNAN and CAROLINE MARUs.
E 7 November 1943:
Arrives at Truk. CH-31 is detached.
24 November 1943:
CH-31 and CH-29 and destroyer URAKAZE arrive at Truk's South Channel escorting a convoy of four unidentified ships.
11 December 1943:
At 1000, CH-31 departs Yokosuka with kaibokan OKI and patrol boat PB-46 escorting convoy No. 3211A consisting of auxiliary storeship SHINYO, MITAKESAN and HAKOZAKI MARUs.
14 December 1943:
HAKOZAKI MARU is detached for Chichi-Jima with engine trouble, together with auxiliary storeship SHINYO MARU, both accompanied by PB-46.
15 December 1943:
At 1100, CH-31 and destroyers ASANAGI and OITE depart Truk escorting convoy No. 1152 consisting of JUZAN and auxiliary storeship HARUNA MARUs.
19 December 1943:
W of Cape Matanalem, New Hanover. At 1235, the convoy is attacked by unidentified bombers at 02-41N, 148-57E, but they are driven off and inflict no damage.
20 December 1943:
At 1500, the convoy arrives at Rabaul.
24 December 1943:
Departs Truk on an anti submarine sweep.
27 December 1943:
Returns to Truk.
28 December 1943:
At 1500, Lt Fukase Eijiro’s CH-31 departs Truk for Kwajalein with CH-30 escorting a convoy consisting of SHOHO (1936 grt) and HOKUJO MARUs.
31 December 1943:
Eastern Carolines. At about noon, LtCdr (later Cdr) James D. Grant's (USNA ’31) USS GREENLING (SS-213) torpedoes and sinks transport SHOHO MARU (1936 grt) at 05-18N, 160-20E. 20 crewmen are KIA. USS GREENLING evades 18 depth-charges in counterattacks by the escorts.
1 January 1944:
At 0940, CH-31 arrives at Kusaie.
2 January 1944:
At 0745, departs Kusaie. CH-31 apparently detaches and sails to Ponape on an escort mission.
4 January 1944:
Arrives at Kusaie.
6 January 1944:
departs Kusaie for Ponape on an escort mission.
8 January 1944:
Departs Ponape for Kusaie on an escort mission.
10 January 1944:
Arrives at Kusaie.
11 January 1944:
Departs Kusaie on an escort mission to Ponape.
14 January 1944:
Arrives at Ponape.
16 January 1944:
CH-31 conducts an ASW sweep, then departs Ponape for Truk with destroyers SUZUKAZE and URAKAZE and auxiliary submarine chaser TAKUNAN MARU No. 8 escorting convoy No. 6163 consisting of NICHIRAN, RYOYO and MATSUE MARUs.
19 January 1944:
At 0730, arrives at Truk.
20 January 1944:
Departs Truk escorting a convoy to Kwajalein.
26 January 1944:
Arrives at Kwajalein.
1 February 1944:
Departs Kwajalein escorting a convoy to Truk.
4 February 1944:
Arrives at Truk.
5 February 1944:
Departs Truk on a rescue mission.
8 February 1944:
Returns to Truk.
13 February 1944:
Departs Truk for Yokosuka with kaibokan MANJU and OKI escorting convoy No. 4212 consisting of fleet oiler NOTORO, fleet supply ship IRAKO and TATSUURA and HIBI MARUs. At some unknown point CH-31 is detached.
25 February 1944:
On that day, FRUMEL decrypts the following order transmitted by Truk Base Force to the CO of CH-31:
"Search outside Ottashima, Hanashima, and Sarashima Channels for the enemy submarine which escaped from inside the reef."
25 February 1944:
CH-31 (and the following day CH-28) depart Truk on an escort mission to Mereyon.
1 March 1944:
CH-28 and CH-31 depart Mereyon on an escort mission to Truk.
3 March 1944:
Arrives at Truk.
4 March 1944:
CH-28 and CH-31 depart Truk on an escort mission to Saipan.
6 March 1944:
Arrives at Saipan.
10 March 1944:
At 0528, CH-31 departs Saipan for Truk with CH-28 and auxiliary minesweepers FUMI MARU No. 2 and SEKI MARU escorting convoy 3310 consisting of TOYOKAWA and IKUSHIMA MARUs. After departure, the convoy's destination is changed to Palau.
15 March 1944:
Arrives at Palau. Soon after departs on an anti submarine sweep.
17 March 1944:
Arrives at Truk. At 2345 CH-28, CH-31 and CH-32 and auxiliary minesweepers SEKI MARU No. 3 and FUMI MARU No. 2 depart Truk escorting a convoy to Mereyon and Saipan consisting of BINGO, TATSUHARU and IKUSHIMA MARUs and possibly others.
22 March 1944:
At 0630 arrives At Saipan.
24 March 1944:
At 0700, CH-31, CH-17 and CH-32 departs Saipan with destroyers NOWAKI and ASAKAZE, kaibokan MANJU and minelayer KYOSAI escorting convoy HIGASHI MATSU No. 2 (return) consisting of fleet supply ship SOYA and TAKUNAN, NACHI, AWA (ex-Panamanian WAWA), DAITEN, MIHO, BINGO, RYUKA, TAKAOKA, HIBI, TAMAHOKO, TATSUHARU, TAJIMA and SHINFUKU MARUs.
1 April 1944:
At 1000, the convoy arrives at Tokyo.
4 May 1944:
At 1400, CH-31, CH-32 and CH-52 depart Tateyama with destroyers ASANAGI, MINATSUKI, torpedo boat OTORI, kaibokan OKI, CD-24 and auxiliary subchaser SHONAN MARU No. 8 escorting convoy 3503 consisting of KEIYO, HAKOZAKI, NICHIWA, ENOSHIMA, MINO, OSAKA, TAIKOKU, FUKKO, TATSUTAGAWA, SHINFUKU, FUKUKOKU, KOHO, KOJUN and SHUNSEN MARUs.
10 May 1944:
420 miles NW of Saipan. At 1743, LtCdr Russell Kefauver’s (USNA ’33) USS TAMBOR (SS-198) torpedoes and damages KEIYO MARU at 19-27N 140-00E.
14 May 1944:
Arrives at Saipan.
16 May 1944:
At 1630, destroyer MINAZUKI and CH-31 and CH-32 depart Saipan for Palau escorting a convoy consisting of FUKKO, NICHIWA, TAIKOKU and OSAKA MARUs.
17 May 1944:
At about 0030, LtCdr Malcolm E. Garrison's (USNA ’32) USS SANDLANCE (SS-381) torpedoes and sinks TAIKOKU MARU. Two crewmen are KIA. The survivors are rescued by either CH-31 or CH-32 and later transferred to MINAZUKI. That same day, at 1840, LtCdr (later Cdr) John A. Scott's (USNA ’28) USS TUNNY (SS-282) torpedoes and sinks NICHIWA MARU. At the time the ship was carrying 2274 troops of the 14th Infantry Division and 324 of them together with one gunner and six crewmen are killed. At 2120, Garrison's USS SANDLANCE strikes again and torpedoes and sinks FUKKO MARU. The vessel is carrying 51 troops from the 15th Regiment and 14 other passengers. One passenger, one gunner and nine crewmen perish. OSAKA MARU is ordered back to Saipan.
E 18 May 1944:
Arrives at Saipan.
3 June 1944:
At 1600, CH-31 departs Truk with kaibokan CD-6, subchasers CH-20, CH-32 and CH-51 and uxiliary subchaser CHa-66 escorting a convoy consisting of MOJI, IMIZU, TATSUTAGAWA, KOJUN MARUs, and oilers NITCHO, KYOEI and NANKO MARU No. 1 and 13 other unidentified ships.
7 June 1944:
At 1140, arrives at Saipan.
12 July 1944:
CH-31 departs Manila for Zamboanga with patrol boat PB-105 (ex-Philippine Customs Cruiser ARAYAT), auxiliary sub-chasers MOGAMI MARU and CHa-84 escorting convoy C-124 consisting of MAYA, TATEISHI, SHIROUMA (HAKUBA) and NATSUKAWA MARUs.
14 July 1944:
At 1050. arrives at Cebu and departs later that day.
16 July 1944:
At 1800, LtCdr William C. Thompson's (USNA ’34) USS CABRILLA (SS-288) unsuccessfully attacks an unknown tanker. The escorts counter-attack and drop 24 depth charges that slightly damage USS CABRILLA.
17 July 1944:
At 0230, USS CABRILLA torpedoes and sinks MAYA MARU. The ship is carrying 36 passengers and war supplies. Six passengers, two gunners and 13 crewmen are killed. Thompson also torpedoes and damages NATSUKAWA MARU.
18 July 1944:
Arrives at Zamboanga. That same day, CH-31 is reassigned to the 3rd Southern Expeditionary Fleet.
19 July 1944:
CH-31 departs Manila with CH-23, CH-32, auxiliary submarine chaser CHa-24 and patrol boat PB-105 escorting convoy H-32 consisting of MIKASA, TAIYU, MIHARA, YAMABUKI, FUSAN, SAIHO, KYOKUZAN, KEIAN, NASUSAN and SHOHO MARUs.
21 July 1944:
At 1200 arrives at Cebu.
23 July 1944:
At 1830 departs Cebu with ASAHISAN MARU as additional convoy member (possibly patrol boat PB-105 only joins at this point, or may have joined between Manila and Cebu).
28 July 1944:
At 1440 arrives at Bitoeng, Halmahera Island.
13 August 1944:
Receives Philippines Island Telegram No. 478:
Subchaser CH-31 on its way to Bitoeng, Halmahera Island, Moluccas, Netherlands East Indies (now Indonesia) is assigned to escort SHIRETOKO between Cebu and Jolo, Sulu Islands, Philippines. During the escort CH-31 is under command of the captain of the SHIRETOKO.
17 August 1944:
At 0050 SHIRETOKO departs Cebu escorted by PB-103, CH-31 and TERUKAZE MARU.
18 August 1944:
CH-31 ends escort and heads towards Zamboanga.
21 August 1944:
At 0850, CH-31 and CH-46 depart Zamboanga for Jolo, Philippines with patrol boat PB-105 and minesweeper W-28 escorting convoy H-33 consisting of MEXICO and HAVRE MARUs.
24 August 1944:
Arrives at Jolo.
27 August 1944:
CH-31 and CH-46 depart Jolo for Menado, Celebes with PB-105 and minesweeper W-28 escorting convoy H-33 consisting of MEXICO and HAVRE MARUs.
29 August 1944:
N of Celebes. At 0225, LtCdr Arthur E. Krapf's (USNA ’34) USS JACK (SS-259) makes a radar-assisted surface attack on the convoy. Krapf torpedoes and sinks MEXICO MARU at 02-15N, 122-29E. She takes down 847 men of the almost 4,300 troops and crew she was carrying and a cargo of food, munitions, oil and gasoline in barrels. CH-31 rescues 760 men, CH-46 935 men and PB-105 1609 men, a total of 3304 survivors.
At about 0400, Krapf makes another surface attack on the convoy. He fires nine torpedoes by radar bearings of which three hit and sink minesweeper W-28 at 02-15N, 123-29E. No counterattacks are made and USS JACK safely departs the scene.
29 September 1944:
Bacuit Bay. Minesweepers W-8 and W-11 join the remnants of convoy MIMA 11/MI-16 consisting of TATSUHARU MARU and tanker KYOEI MARU and probably SHIKISAN, IMAHARU (ex Dutch DE KLERK), TENSHIN and SHOEI MARUs, SHINSEI MARU No. 1 and KYOEI MARU No. 6. [1]
1 October 1944:
Bacuit Bay. CH-31 joins remnants of convoy MIMA-11 then consisting of cargo ships SHIKISAN, TENSHIN, TATSUHARU MARUS, SHINSEI MARU No.1 and tankers KYOEI MARU and KYOEI MARU No.6 escorted by auxiliary minesweeper Wa-8 and Wa-11.
2 October 1944:
Departs Bacuit Bay less TATSUHARU MARU and later that day arrives Busuanga Island.
3 October 1944:
Departs Busuanga Island and later that day arrives Lubang Island.
4 October 1944:
Departs Lubang Island and later that day arrives Manila.
5 October 1944:
At 2222, USN codebreakers intercept and decrypt an order to CH-31, that reads “Subchaser No. 31 --- Masbate will search Masbate and Sibuyan Islands and rescue any survivors of KOOYO MARU she may find; thence, return to Manila.”
25 October 1944:
At 0650, CH-31, CH-5 and patrol boat PB-2 depart Tarakan escorting convoy M-246 consisting of UNKAI MARU No. 12, CAROLINE MARU and oilers TAKASAGO MARU No. 2, NANSHIN MARU No. 8, NANKO MARU No. 1 and HORAI MARU No. 7 At 1437 that day, UNKAI MARU No. 12 runs aground. Patrol boat PB-2 is detached to guard the ship.
29 October 1944:
Arrives at Honda Bay, N of Puerto Princesa. Later that day, UNKAI MARU No. 12 and patrol boat PB-2 rejoin the convoy at Puerto Princesa.
31 October 1944:
At 2000, arrives at Taytay Bay, NE Palawan.
1 November 1944:
Departs Taytay Bay. Later that day, the convoy is attacked by LtCdr George H. Laird's (USNA ’33) USS BLACKFIN (SS-322) and LtCdr (later Rear Admiral-Ret) William T. Kinsella's (USNA ’34) USS RAY (SS-271). At 0923, Laird torpedoes and sinks UNKAI MARU No. 12 and CAROLINE MARU, both with a full load of fuel oil each, at 12-57N, 120-12E. UNKAI MARU No. 12 sinks with the loss of 12 lives, while CAROLINE MARU has 13 crewmen KIA. At 1042, Kinsella sinks HORAI MARU No. 7, carrying 1425 tons of petroleum, at the same location. 10 of the crew are killed. Later that day, the rest of the convoy arrives at Manila.

11 November 1944:
At 2100 departs Manila with submarine chaser CH-30 and patrol boat PB-103 escorting Taihi Refugee convoy consisting of tankers KYOEI MARU No. 3, AYAGUMO and ASOKAWA MARUs.
14 November 1944:
At 1635 arrives at Buliluyan.
15 November 1944:
At 0658 departs Buliluyan. At 1854 arrives at White Rocks Bay.
16 November 1944:
At 1200 departs White Rocks Bay. At 1837 arrives at Jesselton.
17 November 1944:
At 0658 departs Jesselton. At 1542 arrives at Brunei.
18 November 1944:
At 1210 departs Brunei. At 1922 arrives at Patches, an area of submerged reefs, S of the Ampa and Browne Patches, 4-50N, 114-20E.
19 November 1944:
At 0720 departs Patches. At 1839 arrives at Miri.
4 December 1944:
At 0800, CH-31 and CH-30 depart Singapore for Manila with kaibokan CD-43 and patrol boat PB-103 (Ex-USS FINCH, AM-9) escorting convoy SHIMA RINJI consisting of SHOEI, KOSHIN and EIHO MARUs and KYOEI MARU No. 3.
8 December 1944:
NNE of Kuching, Borneo. At 0104, either LtCdr John C. Martin's (USNA ’34) USS HAMMERHEAD (SS-364) or LtCdr Joseph P. FitzPatrick's (USNA ’34) USS PADDLE (SS-263) torpedoes and sinks SHOEI MARU with a cargo of 5,000-tons of gasoline at 04-02N, 111-12E. 42 crewmen are KIA.
12 December 1944:
At 1300, arrives at Kuching.
13 December 1944:
At 1200, departs Kuching.
16 December 1944:
KOSHIN MARU suffers engine trouble and has to be towed to Miri.
18 December 1944:
Arrives at Cape Paloh.
19 December 1944:
Arrives at Pentengu.
23 December 1944:
At 1400, departs Pentengu. At about 2300, that same day, off Kuching, LtCdr (later Captain)Irvin S. Hartman's (USNA ’33) USS BARBERO (SS-317) torpedoes and sinks subchaser CH-30 at 02-42N, 111-05E.
11 January 1945:
At 1100, CH-31 departs Cape St Jacques with kaibokan CD-35, CD-43, patrol boat No. 103 and minesweeper W-101 escorting convoy SATA-05 consisting of KENSEI and TOYU MARUs, Landing Ship Transport T-149 and tankers AYAYUKI, KOSHIN and EIHO MARUs. In the evening, T-149 finds the heavy seas too dangerous. She is detached from the convoy and returns to St Jacques.
12 January 1945: Operation "Gratitude"- Task Force 38's Strikes on Indochina:
Off Cape Paderan, Indochina. Aircraft of Vice Admiral (Admiral Posthumously) John S. McCain's (USNA ’06) Task Force 38 attack SATA-05 and sink the entire convoy including CH-31.
10 March 1945:
Removed from the Navy List.

Authors' Note:
[1] One of these ships, perhaps TENSHIN MARU, left with the fast contingent on 25 September.
Thanks go to John Whitman of the USA for info on CNO intercepts of Japanese messages and to Mr. Gilbert Casse of France for general assistance.

-Bob Hackett, Sander Kingsepp and Peter Cundall

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