Japanese Subchasers

KUSENTEI!
IJN Subchaser CH-56: Tabular Record of Movement
© 2008-2018 Bob Hackett, Sander Kingsepp and Peter Cundall
Revision 7

E 1942:
Osaka. Laid down at Naniwa dockyard.
1943:
Launched and numbered CH-56.
30 November 1943:
Completed and registered in the Yokosuka Naval District. Attached to the Yokosuka Guard Unit. Undergoes training.
2 June 1944:
CH-56 and CH-23 depart Moji with kaibokan CD-14, auxiliary submarine chasers CHa-90 and CHa-95 escorting convoy MOTA-21 (part 1) consisting of AZUCHISAN, HAVRE (5467 gt), NARUO, CLYDE, HAMBURG, SEKIHO, TATSUAKI, SHINSHO, OYO, TSUYAMA, KINE, YAGI, IKOMASAN, TAMA and TAIAN MARUs, SHINSEI MARU No.5, TOYO MARU No.3 and five unidentified merchant ships. At 1700 the convoy arrives at Karatsu Wan.
3 June 1944:
KOTO MARU No. 2 joins from Karatsu Wan. At 0300 the ships depart Karatsu Wan.
7 June 1944:
At 0900, an enemy submarine is sighted at 28-18N, 123-03E. Later that day TAMA MARU and TOYO MARU No. 3 are detached for Kirun, arriving there the next day.
9 June 1944:
At 0900. an enemy submarine is sighted at 24-50N, 120-30E. That same day, OYO MARU, having detached arrives at Kirun at 1030.
10 June 1944:
Arrives at Takao.
25 August 1944:
Reassigned to the Southwest Area Fleet’s Second Southern Expeditionary Fleet’s 22nd Special Base Force at Balikpapan, Borneo.
11 September 1944:
At 1500, CH-56 departs Moji for Takao with destroyer HARUKAZE, kaibokan CD-9 and CD-26 escorting convoy MOTA-26 consisting of GASSAN, SEIZAN, HAKUSAN, HOTEN, MURORAN, MANILA, MACASSAR, DAIIKU, DAIKYO, NANKING, FUYUKAWA, PEKING, DAIZEN, HIDA, ROKKOSAN and JUNPO MARUs and NICHIYU MARU No. 2 and tanker DAISHO MARU.
16 September 1944:
GASSAN, SEIZAN and HAKUSAN MARUs split from the convoy and later that day arrive at Keelung, Formosa.
17 September 1944:
At 1300, arrives at Takao.
25 September 1944:
At 1400, CH-56 departs Takao with destroyer HARUKAZE, kaibokan CD-6, CD-9, CD-16 and fleet stores ship KURASAKI escorting convoy TAMA-27 consisting of DAIBIN, MANILA, DAIKYO, SAN DIEGO MARUs, very likely DAIIKU, SHUNSHO MARUs and NICHIYU MARU No. 2 and four unidentified merchant ships.
26 September 1944:
At 2000 arrives in the Sabtang Channel.
27 September 1944:
At 0300 departs and at 1900 arrives at Aparri.
28 September 1944:
At 0100 departs Aparri and at 1800 arrives at Lapoc Bay.
29 September 1944:
At 0600 departs Lapoc Bay and at 1600 arrives at San Fernando.
30 September 1944:
At 0600 departs San Fernando. Later an enemy submarine contact is made. At 1600 arrives back at San Fernando.
2 October 1944:
Departs San Fernando.
3 October 1944:
At 1800 arrives at Masinloc.
4 October 1944:
At 0630, departs Masinloc. At 0855, Cdr (later Rear Admiral) Reuben T. Whitaker's (USNA ’34) USS FLASHER (SS-249) torpedoeds and sinks DAIBIN MARU, which had detached with KURASAKI, at 15-15N, 119-50E. The ship is carrying the 2nd and 5th Companies of the 10th Tank Regiment, 2nd Tank Division, the 5th Company of that division engineers, elements of the 2nd division’s transport regiment and elements of the (non-divsisional) 27th Signal Regiment as well as 618 base construction personnel aboard of whom 68, as well as 8 out of 33 passengers and 34 of the crew are KIA. Late that day, the remaining ships arrive at Manila.
6 October 1944:
Fleet oiler SHIRETOKO departs Manila with small tanker KYOEI MARU. It is unclear whether there is an escort. Stops briefly at Lubang Island before resuming voyage.
7 October 1944:
NW of Manila. At 0334, LtCdr James A. Adkins' (USNA ’26) USS COD (SS-224) attacks SHIRETOKO by SJ radar. He fires four torpedoes on radar bearings and range and gets two hits at 13-30N, 119-20E. Later that day, arrives at Busuanga anchorage and stays there carrying out urgent repairs for the next five days.
12 October 1944:
Departs Busuanga. Later that day, arrives at Tawi Tawi.
13 October 1944:
Departs Tawi Tawi. Later that day, arrives at Puerto Princesa, Palawan Islands.
16 October 1944:
Departs Puerto Princesa. Later that day, arrives at Brookes Point.
17 October 1944:
Departs Brookes Point. Later that day, arrives at Banggi Island.
18 October 1944:
CH-56 joins the convoy as escort. Later that day, tanker SHUNTEN MARU and minesweeper W-105 also join the convoy.
19 October 1944 :
Departs Banggi Island and reaches Kudat later that day. SHUNTEN MARU and W-105 probably are detached.
20 October 1944:
Departs Kudat. Later that day, arrives at Turtle Island.
21 October 1944:
Departs Turtle Island.
22 October 1944:
Arrives at Tarakan.
24 October 1944:
Departs Tarakan and anchors for the night at Moeara Pantai, Berau Estuary.
25 October 1944:
Departs Moeara Pantai. Later that day, arrives at Sangkulirang Bay.
26 October 1944:
Departs Sangkulirang Bay. Later that day, arrives at Muara Pagar, Koetei (Mahakam) estuary.
27 October 1944:
Departs Muara Pagar. Later that day, arrives at Balikpapan.

12 November 1944:
CH-56 departs Singapore escorting convoy SHISA-29 consisting of HIDA MARU and seven unidentified merchant ships.
16 November 1944:
Arrives at St Jacques.
18 November 1944:
At 0645, CH-56 departs Singapore for Manila with kaibokan KURAHASHI, CD-31 and CD-32 escorting convoy SHIMA-05 consisting of MANILA, KENEI and TASMANIA MARUs and SHINSEI MARU No. 5 and tanker AYANAMI MARU and one unidentified merchant ship. At 1448 LST T-149, which departed Singapore earlier that day, joins the convoy.
20 November 1944:
The convoy arrives at Cape Datu, Borneo (now Malaysia).
21 November 1944:
The convoy departs Cape Datu.
22 November 1944:
At 0730 patrol boat PB-104 departs Singapore and joins the convoy en route.
23 November 1944:
At 1030 comes alongside T-149 and is supplied with water.
24 November 1944:
The convoy arrives at Miri, Borneo and departs at 1710. KENEI MARU, T-149 and the unidentified ship remains behind.
25 November 1944:
At 0535, LtCdr John R. Madison's (USNA ’37) USS MINGO (SS-261) torpedoes MANILA MARU and gets three hits. Loaded with ammunition and gasoline, MANILA MARU explodes and sinks in four minutes at 05-42N, 113-15E. Captain Uike Matsuichi, 96 crewmen, 51 gunners and four passengers die in the sinking. Also lost are cargo of gasoline and 10 Daihatsu barges. The escorts do not counter-attack.
29 November 1944:
SHIMA-05 arrives at Manila.
4 December 1944:
At 1100, CH-56 departs Manila for Singapore with patrol boat PB-104 (ex-Dutch VALK), auxiliary subchaser KYO MARU No. 13 and auxiliary netlayer TOKACHI MARU escorting a convoy consisting of AYANAMI and SHOEI MARUs and BANSHU MARU No. 63.
5 December 1944:
AYANAMI MARU has engine trouble and is detached back to Manila.
13 December 1944:
At 1625, arrives at Singapore.
1944-1945:
Based at Surabaya, Java. Escorts convoys.
8 April 1945:
At 1505, USN codebreakers intercept and decrypt a message from CH-56 that reads: “At 1350 enemy submarine made torpedo attack on transport unit in position 06-30S, 113-08E. Mopping up unit No. 2 will sortie immediately and attack and sink the enemy.”
23 April 1945:
At 2000, departs Surabaya escorting three small ships of 150 tons each (probably wooden "Shuttleboats"). A FRUMEL decrypt adds the planned speed, 5 kts.
28 April 1945:
Arrives at Balikpapan.
At 1348, codebreakers intercept and decrypt a message from CH-56 responding to orders to rescue survivors: “Reference Serial 281045, expect to rescue personnel aboard Shuttle Vessel No. 302, which has run aground at Sebangkatan Island, when this convoy passes there the afternoon of the 30th.”
30 April 1945:
At 1707, codebreakers decrypt a message from CH-56 that reads: “Communication Boat No. 302 ran aground on the north side of Salinguigan Island, 02-19S, 117-14E. Part of the crew (including the Captain, 3 Japanese, and 7 (natives ?) were rescued. The others ---.”
8 May 1945:
On that day, FRUMEL provides the following information: "No. 2 SHOONAN MARU was ordered at 1721 on 8th to proceed to where Subchaser No. 56 is ashore in 4-43S, 119-03E and tow her off."
20 June 1945:
On that day, FRUMEL intercepts East Indies Order 647: "Patrol Boat No. 2, Minesweeper No. 8 and Subchaser 56 are to go to Barito River Mouth at 0200 on X day to carry out Phase 2 of HO-GO Operation. X day is 23rd June."
(According to an attached FRUMEL comment, ETA Soerabaya of the 3 above vessels was later given as 1030 on 24th.)
21 June 1945:
On that day, FRUMEL provides the following information: "Soerabaya reported at 201115 that the Southern Swept Channel was swept clear and the ban on navigation lifted, but later reported Subchaser 56 struck a mine off WA buoy and the ban reimposed."
15 August 1945: End of Hostilities:
Surabaya. Handed over to Allied coalition forces. Later scrapped.
3 May 1947:
Removed from the Navy List.

Authors’ Notes
Thanks go to John Whitman of the USA for info on CNO intercepts of Japanese messages and to Mr. Gilbert Casse of France. Special thanks go to Hans Mcilveen of the Netherlands for info on FRUMEL intercepts.
-Bob Hackett, Sander Kingsepp and Peter Cundall.

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