IJN Subchaser CH-51:
Tabular Record of Movement
© 2005-2013 Bob Hackett, Sander Kingsepp and Peter Cundall
1 April 1943:
Koyagi. Laid down at Kawaminami’s shipyard.
31 July 1943:
Numbered CH-51. Tentatively attached to Yokosuka Naval District.
1 September 1943:
Launched and numbered CH-51.
8 November 1943:
Completed and registered in the Yokosuka Naval District. Attached to the Yokosuka Guard Force.
Escorts an unidentified convoy to Chichi-Jima, Bonin Islands.
15 January 1944:
CH-51 departs Chichi-Jima for Minami Torishima (Marcus Island) accompanied by auxiliary netlayer KOGI MARU escorting YOSHIDA MARU.
18 January 1944:
LtCdr (later Rear Admiral) Reuben T. Whitaker's (USNA '34) USS FLASHER (SS-249) torpedoes and sinks YOSHIDA MARU at 23-46N, 151-30E.
YOSHIDA MARU was carrying 129 naval personnel, 116 civilian employees and 1,394-tons of military supplies. 76 passengers, eight crewmen and 15 gunners are KIA.
24 January 1944:
At 1200, arrives at Minami Torishima.
3 March 1944:
At 1007 CH-14 and CH-51 depart Chichi Jima.
6 March 1944:
At 1130, convoy No. 4304 consisting of URAKAMI, SHIRANE, JUZAN and AWAJI MARUs also escorted by kaibokan AMAKUSA and MIKURA, minesweeper W-21 and subchaser CH-33 departs Truk.
E 7 March 1944:
Submarine Chasers CH-14 and CH-51 join as additional escorts.
10 March 1944:
At 1222, arrives at Saipan.
22 March 1944:
Tokyo Bay. CH-51 departs Kisarazu for Saipan with DesDiv 5's HATAKAZE, DesDiv 6's IKAZUCHI and DesDiv 32's TAMANAMI, torpedo boat OTORI, kaibokan HIRADO and NOMI and subchasers CH-48 and CH-54 escorting Marianas troop reinforcement convoy Higashi Matsu "East Pine" No. 3" consisting of 11 transports, and supply ship HAYASAKI.
25 March 1944:
The convoy is attacked by LtCdr (later Rear Admiral-Ret) Bafford E. Lewellen's (USNA '31) old USS POLLACK (SS-180). Lewellen sinks subchaser CH-54 (casualties unknown) and claims damage to several transports.
30 March 1944:
Arrives at Saipan.
3 June 1944:
At 1600, CH-51 departs Truk Atoll with kaibokan CD-6, subchasers CH-31, CH-32 and CH-20 escorting a convoy consisting of MOJI, IMIZU, TATSUGAWA, KOJUN, NITCHO, KYOEI MARUs and NANKO MARU No. 1 and 13 unidentified ships.
7 June 1944:
At 1140 arrives at Saipan.
11 June 1944:
At 0400, CH-51 departs Saipan for Tokyo Bay with kaibokan CD-4, torpedo boat OTORI, subchasers CH-33, CH-50 auxiliary subchasers TAKUNAN MARU No. 8, CHa-20 and CHa-50, auxiliary minesweeper Wa-6 and auxiliary netlayer KOKKO MARU escorting convoy No. 4611 consisting of BATAVIA, HINKO, SHINTO (KAMISHIMA), IMIZU, NITCHO, REIKAI, TENRYUGAWA, KEIYO, BOKUYO (MUTSUYO), FUKOKU, MOJI, MAMIYA, INARI and TATSUTAKAWA MARUs, NISSHO MARU No.1 and 16 other unidentified ships.
12 June 1944: American Operation “Forager” – The Invasion of Saipan:
Vice Admiral (later Admiral) Richmond K. Turner’s (USNA '11) Task Force 52 lands Marine LtGen Holland M. Smith’s V Amphibious Corps and the invasion of Saipan begins. Vice Admiral (later Admiral) Marc A. Mitscher’s (USNA '10) Task Force 58 launches aircraft from 15 carriers to attack airfields, defenses and shipping in the Marianas.
At 0935, that same day, at 17-32N, 144-10E, TG 58.4’s carriers USS ESSEX (CV-9), USS LANGLEY (CVL-27) and USS COWPENS (CVL-25) find and decimate convoy No. 4611. They sink OTORI, KOKKU, BATAVIA, HINKO (damaged but sunk later in month), SHINTO (KAMISHIMA), IMIZU, NITCHO, REIKAI, TENRYUGAWA, BOKUYO, FUKOKU, MOJI and TSUSHIMA MARUs and damage TATSUTAKAWA MARU, CD-4, CH-33, CH-50 and CH-51, CHa-20 and Wa-6. 
19 June 1944:
CH-51 arrives at Yokosuka and puts 3 wounded men ashore.
1 July 1944:
Arrives at Chichi-Jima.
3 July 1944:
7 July 1944:
Arrives at Nagaura.
11 July 1944:
14 July 1944:
At 1440, CH-51 departs Tateyama for Iwo Jima with kaibokan CD-4, subchaser CH-50 and Navy Landing Ships No. 2 and No. 105 escorting convoy No. 3714 consisting of NISSHU, HASSHO, KATASURAGAWA MARUs and UNKAI MARU No. 10
17 July 1944:
UNKAI MARU No. 10 straggles behind the convoy.
18 July 1944:
At about 0200, LtCdr 's Albert L. Becker's (USNA '34) USS COBIA (SS-245) torpedoes and sinks UNKAI MARU No. 10 at 28-58N, 139-04E. 19 crewmen are KIA.
At 0650, USS COBIA attacks the main convoy. Becker torpedoes and sinks NISSHU MARU at 28-40N, 139-25E. 48 IJA soldiers, three crewmen and 45 gunners are KIA.
29 July 1944:
CH-51 and CH-52 departs Tateyama for Chichi-jima with destroyer escort MATSU, flagship of the 2nd Convoy Escort Group's Commander Rear Admiral Takahashi Ichimatsu (40)(former CO of TSUGARU), destroyer HATAKAZE, kaibokan CD-4, CD-12, and Navy transport landing ships T-2 and T-4 escorting convoy No. 3729 consisting of SHOGEN, TONEGAWA, ENJU, KYUSHU and HOKKAI MARUs and UNKAI MARU No.7.
That same day, light carrier ZUIHO, escorted by destroyer FUYUTSUKI, sorties from Yokosuka to provide air and anti-submarine cover for the convoy.
1 August 1944:
Arrives at Futami Harbor, Chichi-jima. Upon arrival, some of the cargo ships depart for Iwo Jima. Bad weather causes delays in unloading. ZUIHO and FUYUTSUKI, after maintaining position near the lzu Shichi Islands, make for the West Inland Sea..
4 August 1944:
About 0930, an air raid warning is received from Tokyo. All ships proceed to sea in convoy No. 4804. From 1030 on, the convoy is attacked by three waves of aircraft of Rear Admiral (Admiral-Ret) Joseph J. Clark's (USNA '37)(former CO of USS YORKTOWN, CV-10) Task Group 58.1. The first wave attacks the convoy 20 miles NW of Chichi-Jima. Destroyer HATAKAZE suffers rudder damage. At about 1100, CD-4 is
near-missed by bombs fore and aft to starboard. She suffers slight damage with two men KIA. The Japanese claim shooting-down several aircraft.
In the second raid, ENJU MARU is sunk. 21 passengers and 52 crewmen are killed. The third strike occurs between 1600 and 1630, during which the majority of the ships succumb to torpedo attacks from both sides of the convoy. CD-12 incurs some damage. After organizing the rescue of the convoy’s survivors, flagship MATSU leads the still intact escort group and TONEGAWA MARU, the lone surviving cargo ship, northwards.
At 1254, Rear Admiral (Admiral-Ret) Laurance T. DuBose's (USNA '13) Task Unit 58.1.6 consisting of CruDiv 13’s USS SANTA FE (F) (CL-60), USS MOBILE (CL-63), USS BILOXI (CL-80) and USS OAKLAND (CL-95), DesDiv 100’s USS COGSWELL (DD-651), USS INGERSOLL (DD-652) and USS KNAPP (DD-653) and DesDiv 91’s USS IZARD (DD-589), USS CHARRETTE (DD-581), USS BURNS (DD-588) and USS BROWN (DD-546) is detached to sink the cripples.
At 1800, CD-4 sights DuBose's warships closing from the south. Rear Admiral Takahashi orders CD-4 to protect TONEGAWA MARU and continue fleeing while his flagship MATSU attempts to draw off the Americans. At 1930, MATSU is taken under fire and sunk by shell fire of USS COGSWELL, USS INGERSOLL and USS KNAPP at 27-40N, 141-48E. Rear Admiral Takahashi is KIA, as are all but six of MATSU's crew. He is promoted Vice Admiral, posthumously.
Later, the Americans overtake and sink TONEGAWA MARU. 61 gunners and 83 crewmen are killed. CH-51, HATAKAZE and CD-4 and CD-12 escape.
E 9 August 1944:
Arrives at Tateyama.
23 August 1944:
At 1400, CH-51 departs Yokosuka with auxilary minesweepers Wa-11 and Wa-14 escorting convoy No. 3823B consisting of midget submarine HA-66 towed by 479 grt NAGATA MARU, midget submarine HA-71 by 315 grt HAKUGIN MARU and midget submarine HA-75 by 376 grt FUYO MARU escorted by subchaser CH-51, auxilary minesweepers Wa-11 and Wa-14. The convoy's planned arrival at Chichi-jima is 1930, 27 Aug '44, but soon after departure encounters a typhoon. FUYO MARU later turns back to Tateyama with HA-75.
30 August 1944:
At 0530, HAKUGIN MARU and HA-71 arrive at Hachijo-Jima. At 2200, NAGATA MARU and HA-66 arrive at Chichi-jima.
31 August 1944:
CH-51 arrives at Yokosuka.
1 September 1944:
CH-51 departs Yokohama with torpedo boat CHIDORI and kaibokan OKI escorting convoy No. 3901 consisting of KYUSHU MARU and TOKAI MARU No. 4. Arrives at Tateyama later that day.
5 September 1944:
At 0700, departs Tateyama.
10 September 1944:
Arrives at Chichi Jima. At 1600, CH-51 departs for Yokosuka with kaibokan (ex-Chinese light cruiser) YASOJIMA and auxiliary subchaser TAKUNAN MARU No. 10 escorting convoy No. 4901A consisting of NAGATA and TAKUNAN MARUs and HAKUUN MARU No. 2.
11 September 1944:
At 0400, LtCdr Robert R. William's (USNA '34) USS FINBACK (SS-230) torpedoes and sinks HAKUUN MARU No. 2 at 27-45N, 140-00E. Four men are KIA.
14 September 1944:
The remainder of convoy No. 4901A arrives at Yokosuka.
23 September 1944:
CH-51 departs Yokohama with submarine chaser CH-44 and kaibokan CD-12 escorting convoy No. 3923 consisting of IKUTAGAWA, SHIBAZONO MARUs and Oil Tanker No. 3998 bound for Chichi-Jima. En route IKUTAGAWA MARU is detached at Hachijo Jima.
30 September 1944:
At 2200 CH-51 departs Chichi-Jima with submarine chasers CH-44 and kaibokan CD-12 escorting convoy No. 4930 consisting of SHIBAZONO MARU and Oil Tanker No. 3998 bound for Yokosuka.
4 October 1944:
At 1600 arrives at Yokosuka.
11 October 1944:
At 0800, CH-51 departs Yokosuka with kaibokan OKI escorting convoy No. 3009 consisting of MUTSUKI MARU.
16 October 1944:
Arrives at Chichi Jima.
18 October 1944:
At 1400, CH-51 departs Chichi-Jima with MUTSUKI MARU and OKI. At 0955 arrives at Hahajima. At 1055, 15 B-24 "Liberator" heavy bombers attack the convoy. After several near misses, MUTSUKI MARU has to be beached, a total loss. She was carrying 120 troops, cement, timber and ammunition. Two escort guards are killed. The convoy is dissolved.
19 October 1944:
CH-51 and kaibokan OKI depart Chichi-Jima escorting convoy No. 4019 consisting of SHOTO MARU for Yokohama.
23 October 1944:
Arrives at Yokosuka.
2 November 1944:
Transfers from Yokosuka to Yokohama.
3 November 1944:
Departs Yokohama and arrives at Yokosuka.
4 November 1944:
CH-51, CH-44 and CH-52, kaibokan CD-4 and auxiliary submarine chaser TAKUNAN MARU No. 2 depart Tateyama escorting convoy No. 3103 consisting of KAIKO, SHIBAZONO, SHOTO MARUs and OIL TANKER No. 3998.
8 November 1944:
Arrives at Chichi-Jima. Late that day CD-4 with submarine chasers CH-44, CH-51, CH-52 and auxiliary submarine chaser TAKUNAN MARU No. 2 departs Chichijima escorting convoy No. 4108 consisting of KAIKO, SHIBAZONO, SHOTO MARUs and OIL TANKER No. 3998.
11 November 1944:
N of Hachijo Island. A patrol bomber from the 901st NAG spots a submarine in that area, attacks it with depth charges and then conducts CD-4 to the scene of attack. An oil slick is sighted and soon a sonar contact is made from a distance of 3,300 yds.
LtCdr John G. Hollingsworth's (USNA ’31) USS SCAMP (SS-277) attempts to attack the approaching escort, firing a divergent spread of three torpedoes from a distance of 1,100 yds. LtCdr Mizutani evades all of them and conducts three depth charge attacks. After a total of 70 depth charges have been expended, several giant air bubbles and large quantities of oil are sighted on the surface.
USS SCAMP is lost with all 83 hands at 33-38N, 141-00E.
12 November 1944:
Arrives at Tateyama.
13 November 1944:
Arrives at Yokosuka.
17 November 1944:
25 November 1944:
Arrives at Yokosuka.
1 December 1944:
CH-51 and CH-52 transfer from Yokosuka to Yokohama.
4 December 1944:
CH-51 and CH-51 depart Yokohama and arrive at Tateyama.
5 December 1944:
CH-51, CH-44 and CH-52 depart Tateyama for Hachijo Jima with destroyer HATAKAZE and auxiliary submarine chasers SHONAN MARU No. 8 and KYO MARU No. 7 escorting convoy No. 3203 consisting of DAISHO, AITOKU MARUs and SEIKAI MARU No. 2. Enroute, CH-52 collides with CH-51 and CH-52's bow is damaged. CH-51 is forced to return to Yokosuka for repairs escorted by CH-52.
8 December 1944:
At 1300 CH-51 returns to Yokosuka escorted by CH-52. Thereafter, undergoes repairs.
24 January 1945:
26 January 1945:
At 0900, CH-51 departs Yokosuka for Chichi-Jima with kaibokan CD-47, subchaser CH-52 and auxiliary subchaser TAKUNAN MARU No. 10 escorting convoy No. 3126 consisting of AITOKU, TAISHO, KYUSHU and RYUJIN MARUs. Anchors overnight at Tateyama.
29 January 1945:
At 0600, departs Tateyama. At 2108, three North American B-25 “Mitchell” medium bombers attack the convoy. They hit auxiliary subchaser TAKUNAN MARU No. 10 with five rockets that leave her flooding and unnavigable. At about 0200, CH-52 takes her under tow, but the tow line parts and TAKUNAN MARU No. 10 sinks. Two crewmen are KIA. CD-47 is also damaged by the planes, probably by strafing, at 27-45N, 142-00E.
30 January 1945:
The convoy arrives at Chichi-Jima and unloads. At 2230, all ships depart except RYUJIN MARU forming convoy No. 4130.
3 February 1945:
Arrives at Tateyama.
Escorts convoys to Hachijo-Jima.
3 March 1945:
CH-51 and kaibokan CD-6 depart Tokyo escorting a convoy consisting of NIKKO MARU No. 2 and TOKO MARU bound for Hachijo Jima.
4 March 1945:
Arrives at Hachijo Jima.
7 March 1945:
At 2138 a B-24 attacks the convoy off Hachijo Jima and damages CH-51. As a result the ships quickly discharge all troops but only some cargo.
9 March 1945:
The same convoy now restyled 4309 departs Hachijo Jima and later that day arrives at Tateyama Wan.
10 March 1945:
CH-51 arrives at Tokyo Bay and spends the rest of the month under repair.
7 April 1945:
8 April 1945:
Arrives at Yokosuka.
12 April 1945:
16 April 1945:
Arrives at Yokosuka.
27 April 1945:
28 April 1945:
Arrives at Shimoda.
29 April 1945:
Departs Shimoda escorting convoy No. 3428 consisting of NANYO MARU No. 1 and later arrives at Hachijo Jima.
3 May 1945:
Arrives at Yokosuka.
24 June 1945:
CH-51 departs Yokosuka with kaibokan SHISAKA escorting convoy No. 1624 consisting of EIKAN, KAMITSU MARUs and fleet supply ship SOYA.
26 June 1945:
At 1030, LtCdr Woodrow W. McCrory's (USNA '38) USS PARCHE (SS-384) torpedoes and sinks KAMITSU MARU at 39-25N, 142-04E. 192 men are KIA.
USS PARCHE also damages EIKAN MARU that is beached on shore at Iwate Ken. One crewman is KIA. After some cargo is salvaged, EIKAN MARU later breaks in two. After further attacks by carrier aircraft, she is abandoned.
During a counterattack by CH-51, USS PARCHE fires a Mark 27 "Cutie" acoustic homing torpedo at CH-51, but it misses. The convoy proceeds to Hakodate.
15 August 1945: End of Hostilities:
Yokosuka. CH-51’s crew is notified of Japan’s surrender.
15 September 1945:
Removed from the Navy List.
29 November 1945:
Undergoes repairs at Tsurumi Zosen.
1 December 1945:
Assigned to the Allied Repatriation Service and designated a special transport ship.
28 February 1946:
Repairs are completed, but CH-51 never makes any repatriation voyages.
1 August 1948:
 MAMIYA MARU is detached from the convoy and sunk three days later near Iwo Jima. TATSUTAGAWA MARU is left drifting and is finished off by gunfire three days later.
Thanks to Mr. Gilbert Casse of France.
-Bob Hackett, Sander Kingsepp and Peter Cundall.
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