KUSENTEI!

© 2005-2010 Bob Hackett, Sander Kingsepp and Peter Cundall

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1941:
Okajima. Laid down at Tama Shipbuilding's yard.

29 May 1941:
Launched and numbered CH-20.

20 August 1941:
Completed and registered in the Kure Naval District.

8 December 1941:
Assigned to the Kure Guard Unit. Conducts patrols in the Bungo Straits.

February 1942:
Reassigned to the 1st Base Force. Conducts patrols from Staring Bay, Celebes.

10 March 1942:
Makassar, Celebes (now Sulawasei). Reassigned to the 2nd Southern Expeditionary Fleet in Captain (later Vice Admiral)(40) (former XO of ATAGO) Mori Kunizo's 23rd Special Base Force with CH-19 and CH-21. Escorts convoys.

8-16 May 1942: Operation "S" – The Seizure of the Lesser Sunda's:
CH-20 departs Surabaya escorting seaplane tender SANYO MARU that begins air support of a combined Army/Navy Operation to "sanitize" an area that includes Lombok, Sumbawa, Flores and the Bali Islands. No resistance by the Dutch is encountered.

8 December 1942:
CH-2 departs Surabaya with minesweeper W-11 and auxiliary gunboat OKUYO MARU escorting the Oki convoy consisting of an unidentified number of merchant ships.

13 December 1942:
Minesweeper W-11 is detached.

14 December 1942:
Subchaser CH-2 is detached.

15 December 1942:
Subchaser CH-20 joins convoy.

18 December 1942:
Subchaser CH-18 joins convoy and CH-20 is detached.

22 December 1942:
An unknown submarine attacks the convoy. OKUYO MARU drops three depth charges. Later that day the convoy arrives at Rabaul. 13 January 1943:
CH-20 departs Palau with auxiliary subchasers SHOWA MARU and GANJITSU MARU No. 1 escorting a convoy consisting of SHIRAHA, KENZAN, HOEISAN and GENOA MARUs.

14 January 1943:
At 1150, auxiliary subchaser GANJITSU MARU No. 1 and cargo ship SHIRAHA MARU are torpedoed and sunk by LtCdr (later Rear Admiral-Ret) Hiram Cassedy's USS SEARAVEN (SS-196) at 09-32N, 130-42E.

18 January 1943:
Arrives at Manila.

17 April 1943:
At 1200, departs Truk via the south channel.

17 August 1943:
Malacca Straits. CH-20 joins transport NANKAI MARU that is returning from Car Nicobar Island. [1]

18 August 1943:
Arrives at Singapore's commercial port.

7 November 1943:
At 1200 CH-20 departs Penang Island and arrives in her designated anti-submarine sweep area at 1330.

9 November 1943:
CH-20 conducts an anti-submarine sweep in the vicinity of Penang. At 1516, CH-20 drops seven depth charges on a submarine contact for obscure results.

14 November 1943:
At 0400, CH-20 heads for the Bandan Island, west of Penang. At 0605, CH-20 discovers a surfaced enemy submarine at 56 degrees, 10 miles from Jarak Island. She advances towards it. When the range is down to 4000 metres, British submarine HMS TAURUS submerges. At 0630, CH-20 drops two depth charges. At 0812, after regaining contact, another 8 DCs are dropped.

At about 0852, HMS TAURUS resurfaces. Two minutes later a gun duel breaks out. One of CH-20's 8 cm. main gun shells is alleged to have hits the lower part of the submarine's conning tower, but this is doubtful. HMS TAURUS replies with her 10 cm. gun. One shell strikes CH-20's bridge killing her captain and many others. Her chief engineer takes command. Other shells cause extensive damage to her hull. HMS TAURUS goes under again. Despite her damage, CH-20 drops three more depth charges. HMS TAURUS escapes, but CH-20 claims a sinking.

Soon after, CH-20 becomes immobile with flooding in her engine room and auxiliary machinery room. Shell damage is suffered to her hull. Her casualties are three officers, nine petty officers, seven other ranks KIA; one petty officer fatally wounded; six petty officers and 11 other ranks wounded. Afterward, CH-20 is towed by CHOKO MARU to the Howard anchorage where temporary repairs are undertaken.

15 November 1943:
RAITO MARU arrives to assist.

16 November 1943:
RAITO MARU attempts to tow CH-20 with CHOKO MARU providing escort; however, troubles arise.

17 November 1943:
3,712 ton freighter HOKUAN MARU is summoned to assist.

21 November 1943:
At 1130, CH-20 towed by RAITO MARU and escorted by CHOKO MARU departs the Howard anchorage. At 2020, they are joined by HOKUAN MARU, but there are more problems, so they return.

22 November 1943:
At 0800, the group finally departs the Howard anchorage. At 1200, they arrive in the (K) Curan Strait. CH-20 undergoes more temporary repairs.

24 November 1943:
In the morning, departs the anchorage

25 November 1943:
At 1950, CH-20 drops anchor outside Singapore Harbour.

26 November 1943:
At 1755, CH-20 enters the anchorage at Seletar Naval Base. Singapore and begins extensive battle-damage repairs by the IJN’s 101st Repair Unit.

Mid-May 1944:
The repairs are completed.

16 and 19 May 1944:
CH-20 carries out running trials and returns to Singapore each day.

5 June 1944:
CH-20 left Singapore, carried out calibration tests, then returns.

7 June 1944:
CH-20 departs Singapore arriving at Batbhat the same day.

1 August 1944:
Reassigned to the Southwest Area Fleet’s Third Southern Expeditionary Fleet's 21st Subchaser Division with CH-19 and CH-21. Thereafter, escorts convoys to Palau.

17 August 1944 :
CH-20 departs Singapore with kaibokan CD-14 escorting convoy SHIMI-09 consisting of four unidentified merchant ships.

21 August 1944:
Arrives at Kuching to shelter after a torpedo attack on convoy MISHI-07.

24 August 1944:
Departs Kuching.

25 August 1944:
Arrives at Miri.

29 August 1944:
At 0830, CH-20 departs Miri, Borneo with CD-14 and patrol boat PB-38 escorting convoy MI-14 consisting of KENSEI, IIDA, JUZAN, CHUKA and SURAKARUTA MARUs and oilers ATAGAO, OGURA MARU No. 2 and TOKUWA MARUs.

5 September 1944:
Arrives at Manila. The convoy is reformed to consist of TOKUSHIMA, ENOSHIMA, MIHO, KENSEI, KEISHU MARUs and oilers ATAGO, OGURA MARU No. 2, and TOKUWA MARU with the same escorts.

9 September 1944:
At 1600, departs Manila. En route north joins minesweepers W-38 and W-39.

10 September 1944:
Manila. CH-20 is reassigned to the Southwest Area Fleet’s Third Southern Expeditionary Fleet's 31st Special Base Force.

16 September 1944:
At 0440, departs Basco Bay, Batan Island, Philippines. At 1355, TOKUSHIMA MARU is torpedoed and sunk at 21-57N, 121-35E. The explosion damages nearby oiler OGURA MARU No. 2. She stops for repairs, but at 1515, OGURA MARU No. 2 is torpedoed and sunk by LtCdr Louis D. McGregor's USS REDFISH (SS-395) at 21-42N, 121-41E.

17 September 1944:
Arrives at Takao, Formosa. CH-20 is detached from the convoy.

20 October 1944:
At 2340, CH-20 departs Manila for Takao with destroyers HARUKAZE, TAKE and KURETAKE and fleet supply ship KURASAKI escorting convoy MATA-30 consisting of KOKURYU, KIMIKAWA, KIKUSUI, FUYUKAWA, TENSHIN, SHIGISAN, EIKO, ARISAN, RYOFU and DAITEN MARUs and SHINSEI MARU No. 1.

23 October 1944:
South China Sea, WNW of Cape Bojeador, Luzon, Philippines. About 1730 (JST), Cdr Alan B. Banister’s USS SAWFISH (SS-276) attacks ex-seaplane tender KIMIKAWA MARU. She is hit by four of five torpedoes and sinks at 18-58N, 118-46E.

24 October 1944:
The convoy comes under a combined wolfpack attack by five submarines. At 0050, SHINSEI MARU No. 1 is damaged by a dud torpedo at 19-32N, 118-37E. At 0100, KOKURYU MARU is torpedoed and sunk at 19-42N, 118-38E, likely by LtCdr George H. Browne's USS SNOOK (SS-279) or LtCdr Richard W. Peterson's ICEFISH (SS-367). At 0315, KIKUSUI MARU is torpedoed and sunk by SNOOK at 19-46N, 118-30E.

At 0605 TENSHIN MARU is torpedoed twice and sunk by either SNOOK or LtCdr Edward N. Blakely's (later KIA) USS SHARK (SS-314) or both, at 19-54N 119-00E.

At 0758, SHIGISAN MARU is torpedoed by LtCdr (later Rear Admiral) Maurice H. Rindskopf's USS DRUM (SS-228) and sinks in 90 seconds at 20-27N, 118-31E. Soon after, DAITEN MARU is also torpedoed and sunk by LtCdr James H. Ashley's SEADRAGON (SS-194) at 20-12N, 119-01E.

At 1225, straggling SHINSEI MARU No. 1 is torpedoed by SNOOK and sinks in three minutes at 20-31N, 118-42E. At 1405, EIKO MARU is torpedoed by SEADRAGON and sinks at 20-35N 118-32E

Finally, at 1730, ARISAN MARU is torpedoed and sunk, probably by Blakely's SHARK (sunk soon after by HARUKAZE and TAKE) at 20-00N, 118-44E.

26 October 1944:
At 0715, arrives at Takao.

28 November 1944: Operation "TA No. 7" - The Reinforcement of Leyte, Philippines:
At 1350, the first of the movement's three echelons, consisting of IJA landing ships SS-5, SS-11 and SS-12, escorted by CH-20, departs Manila.

29 November 1944:
Masbate Island, Philippines. The first echelon lays over, but landing ship SS-5 goes hard aground and is lost to the operation.

30 November 1944:
S of Ormoc, Philippines. Arrives at Ipil at 2300. The SS-landing ships unload food, ammunition, medical supplies and about 200 men. CH-20 picks up 72 survivors of destroyer NAGANAMI bombed and sunk during TA No. 3. That afternoon, while sheltering at Cebu, 30 planes attack the small convoy, but are driven off by IJN fighters and anti-aircraft fire. None of the SS ships is damaged.

1 December 1944:
At 0140, the unloading is completed. The convoy departs in the early morning covered by bad weather.

2 December 1944:
Arrives at Manila at 1530.

January 1945:
Saigon, Indochina. Reassigned to the 11th Base Force for a second time. Escorts convoys to Saigon.

22 January 1945:
At 0700, CH-20 departs Singapore with kaibokan NOMI, CD-60 and patrol boat PB-104 escorting convoy HI-88-B consisting of DAIETSU, ENKI and TATSUTAMA MARUs.

27 January 1945:
At 2230 arrives at St Jacques, Indochina. TATSUTAMA MARU is detached.

28 January 1945:
At 2110, departs St Jacques.

29 January 1945:
At 2230, arrives Van Phong, Indochina.

30 January 1945:
At 0700, departs Van Phong.

31 January 1945:
After two submarine sightings, at 0551, DAIETSU MARU and one minute later, ENKI MARU are torpedoed and sunk by Cdr Royce L. Gross' USS BOARFISH (SS-327) at 14-56N, 109-00E. DAIETSU MARU is run aground on the coast. Later, the wreck is bombed.

14 February 1945:
At 0800, CH-20 depart Singapores with CH-34, CH-35 and kaibokan CD-31 escorting convoy HI-88-G consisting of IYASAKA MARU No. 1, TAKASAGO MARU No. 2 and NANSHIN MARU No. 30

21 February 1945:
At 0900, arrives St Jacques, Indochina. NANSHIN MARU No. 30 is detached and probably CH-34.

23 February 1945:
Off Cape Padaran, Indochina. Fifth Air Force B-25 "Mitchell" medium-bombers of the 345th Bomb Group's 500th Bomb Squadron attack convoy HI-88-G. The B-25's come under attack by covering IJA and IJN fighters, including a "Rufe" float fighter. At 1714, the B-25's strafe, bomb and sink CH-35 and damage CH-20 and small oiler NANSHIN MARU No. 30 at 10-15N, 107-31E. One of the B-25's is shot down by a subchaser.

25 February 1945:
Convoy HI-88-G arrives at Tourane, Indochina and merges with convoy HI-88-H. The convoy now consists of HONAN MARU and oilers EISHO MARU, YAEI MARU No. 1 and TAKASAGO MARU No. 2 escorted by CH-20, and CH-57, kaibokans CD-13 and CD-31.

27 February 1945:
At 0800, departs Tourane.

28 February 1945:
At 1600, arrives at Yulin, Hainan Island, China.

1 March 1945:
At 1100, departs Yulin. At 2300, the convoy is attacked by a single large bomber. At 2314, EISHO MARU is bombed and sunk at 18-32N, 108-16E.

2 March 1945:
Arrives at Linkao Bay, Hainan Island.

3 March 1945:
At 0115, while still in Linkao Bay preparing to leave, three aircraft attack. YAEI MARU No. 1 is bombed and sunk at 20-10N, 109-31E.

5 March 1945:
CH-20 is reassigned to the General Escort Command’s First Escort Fleet’s 31st Subchaser Division with CH-19, CH-21, CH-26 and CH-60.

17 March 1945:
At 0300, arrives at Moji, Japan.

4 April 1945:
At 1700, CH-20 departs Hong Kong with CH-9, destroyer AMATSUKAZE, kaibokans CD-1 and CD-134 en route to Shanghai escorting convoy HOMO-03 consisting of TOKAI MARU No. 2 and KINE MARU.

5 April 1945:
Hong Kong. Far East Air Force B-24 "Liberator" heavy-bombers sink both TOKAI MARU No. 2 and KINE MARU and damage CH-20, CH-9 and coast defense vessels CD-1 and CD-52 at 22-45N, 116-10E. The B-24's also damage fleet oiler KAMOI. The convoy is dissolved.

6 April 1945:
At 1835, USN codebreakers intercept and decrypt a message from CH-20 that reads: “Because of not being able to proceed northward on account of bad weather and it being inappropriate to remain at this anchorage with survivors aboard, we departed (Nanmangtao ?) at 1800 and headed for Hong Kong. Scheduled to arrive at 1000, 7th.”

7 April 1945:
Arrives at Hong Kong.

26 April 1945:
Coast of China. At 0755, CH-20 departs the Shusan Sea area for Moji with destroyer ASAGAO, kaibokans UKU and CD-25, patrol boat PB-102 (ex-USS STEWART, DD-224) and minesweeper W-29 escorting convoy SHIMO-03 consisting of KASHIMA, BANSHU, ABUKUMAGAWA, SHINTON and TAIKYU MARUs and NANRYU MARU No. 9.

27 April 1945:
Convoy SHIMO-03 is attacked by aircraft and unidentified submarine(s). The planes make many attacks and bomb and strafe the convoy. UKU and patrol boat PB-102 are damaged at 34-52N, 124-23E.

28 April 1945:
At 1200, arrives at Moji.

15 August 1945:
Kure. While CH-20 is undergoing repairs and maintenance, her crew is notified of the termination of hostilities with the Allied Powers.

4 May 1948:
Begins scrapping at the Kawaminami shipyard.

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Authors’ Notes:
[1] It is unclear whether kaibokan SHIMUSHU that escorted NANKAI MARU to Car Nicobar is still an escort, but given size and value of ship this appears likely.

Thanks go to John Whitman of the USA for info on CNO intercepts of Japanese messages. Thanks also go to Bill Somerville for info concerning CH-20's encounter with HMS TAURUS and subsequent events.

-Bob Hackett, Sander Kingsepp and Peter Cundall.

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