RIKUGUN YUSOSEN

KOYO MARU, prewar)

IJA/IJN KOYO MARU:
Tabular Record of Movement

© 2013-2016 Bob Hackett

15 February 1919:
Uraga. Laid down at Uraga Drydock Co. Ltd., as Yard No. 146, a 5,471 ton passenger/cargo ship for the Asano Joint Stock Company, Tokyo.

5 May 1919:
Launched and named KOYO MARU.

5 July 1919:
Completed.

1919:
Sold to Toyo Kisen K. K. (Oriental steamship Co.), Tokyo.

29 September 1941:
Requisitioned by the Imperial Army as a troop transport. Allotted Army No. 142.

18 December 1941: The Invasion of the Northern Philippines:
At 1200, KOYO MARU departs Mako, Pescadores for Lingayen Gulf, Philippines in Rear Admiral (later Vice Admiral) Rear Admiral Nishimura Shoji's (39)(former CO of HARUNA) 2nd Lingayen Invasion Unit with 27 other IJA transports escorted by DesRon 2's light cruiser NAKA, DesDiv 9's ASAGUMO, MINEGUMO, NATSUGUMO, minesweepers W-9, W-10, W-11, W-12, W-17 and W-18 and subchasers CH-4, CH-5, CH-6, CH-10, CH-11, CH-12, CH-16 , CH-17 and CH-18.

The Japanese main invasion at Lingayen Gulf consists of three transport echelons. The first is composed of 27 transports from Takao under Rear Admiral Hara Kensaburo, the second of 28 transports under Rear Admiral Nishimura and the third of 21 transports from Keelung under Rear Admiral Hirose Sueto. This force of 76 transports carries the main part of LtGen Homma Masaharu's 80,000-man 14th Army.

24 December 1941:
KOYO MARU and Rear Admiral Nishimura's 2nd Lingayen Invasion Unit arrive at Lingayen Gulf between 0110 and 0430. At 0530, LtGen Dobashi's 2nd Lingayen Invasion Unit begins landing troops.

21 January 1942: 2nd Infantry Division Transportation Movement:
KOYO MARU departs Moji for Kirun (Keelung), Formosa in the 2nd Transportation Unit with transports ATLAS, GENKAI, HIYORI, RYUNAN and SHINSHU MARUs escorted by DesDiv 27's SHIRATSUYU, SHIGURE, ARIAKE and YUGURE. The transports are carrying the IJA’s 2nd Infantry Division.

22 January 1942:
Arrives at Kirun. Later, the convoy departs for Camranh Bay, Indochina to mobilize for the Invasion of Java.

18 February 1942: Operation "J" - The Invasion of Java, Netherlands East Indies:
KOYO MARU is attached to Vice Admiral Takahashi's Third Fleet, Southern Force, Netherlands East Indies Force in Vice Admiral Ozawa Jisaburo’s Western Java Seizure Force. Departs Camranh Bay in a convoy comprised of 56 troop transports. They carry the 2nd Infantry Division for the invasions of Merak and Bantam Bay, Java escorted by light cruisers YURA and NATORI, DesDivs 5, 6, 11, 12 and 22.

Fifteen transports go to Merak, Java including KOYO, AKITSU, ATLAS, COLUMBIA, HOKOKUMEI (later NIKKEI), KIZAN, MOMOYAMA, PACIFIC, REIYO, RYUNAN, SHINSHU, SYDNEY and TSUYAMA MARUs. Seven transports go to Eretan Wetan. Seaplane tender SANYO MARU provides air cover. Departs Camrahn Bay.

1 March 1942:
Arrives at Merak, Java. Lands troops of the IJA’s 2nd Infantry Division.

9 March 1942:
Arrives at Bantam Bay.

13 March 1942:
Departs Bantam Bay.

16 March 1942:
Arrives at Singapore.

27 March 1943:
At 1336, KOYO MARU departs Cebu, Phillippines for Manila escorted by gunboat KARATSU.

29 March 1943:
At 1330, arrives at Manila.

31 March 1943:
KOYO MARU departs Manila in convoy No. 840 also consisting of KAMO, NANKING and TAIHEI MARUs escorted by destroyer KURETAKE.

5 April 1943:
Arrives at Takao.

19 May 1943:
At 0530, KOYO MARU departs Saeki for Palau, Western Carolines in convoy K-519 also consisting of transports CLYDE, KANAYAMASAN, KOCHI, MOJI, NITTAI, SAIPAN and YAMAGATA MARUs escorted by torpedo boat HATO, minesweeper W-18 and auxiliary minesweeper TAMA MARU No. 6.

E 21 May 1943:
W-18 is probably detached at latitude 29N.

27 May 1943:
Arrives at Palau.

25 July 1943:
At 1345, departs Palau in convoy FU-506 also consisting of HIBI, KOFUKU, MATSUE (SHOKO), MUKO KOYO and YURI MARUs escorted by patrol boat PB-46.

29 July 1943:
At 1500, arrives at Fukashima.

E 31 July 1943:
Minelayer YURIJIMA and auxiliary minesweeper TAKUNAN MARU No. 3 join the convoy at 28-25N, 136-40E.

2 August 1943:
At 1800, arrives at Saeki.

27 November 1943:
At 0800, KOYO MARU departs Saeki in convoy O-703 also consisting of RYUA and SAMARANG MARUs escorted by kaibokan IKI, auxiliary minesweepers OI MARU and TAMA MARU No. 6.

E 28 November 1943:
Both auxiliary minesweepers probably are detached.

E 7 December 1943:
Arrives at Palau.

23 December 1943:
At 1100, arrives at Rabaul, New Britain.

8 January 1944:
KOYO MARU departs Rabaul for Palau in convoy O-805 also consisting of IJA transports CEYLON, MEXICO, NAGISAN and PACIFIC MARUs escorted by subchasers CH-17 and CH-18. CEYLON MARU joined that day from Kavieng.

15 January 1944:
At 1230, arrives at Palau, Western Carolines.

1 February 1944:
Released by the IJA back to her owners.

2 February 1944:
Requisitioned by the Imperial Navy (IJN) as an Ippan Choyosen shared employment cargo ship (B-AK).

21 February 1944:
KOYO MARU departs Yokosuka for Saipan in convoy No. 4220 also consisting of KIMISHIMA and KUMANOSAN (KUMANOYAMA) MARUs and two unidentified ships, escorted by kaibokan FUKAE, minesweepers W-24 and W-25 and auxiliary netlayer TAIKO MARU. KOYO MARU is loaded with 5,000-tons of provisions and construction equipment.

23 February 1944:
At 1226, LtCdr Raymond H. Bass' (USNA ’31) USS PLUNGER (SS-179) torpedoes KIMISHIMA MARU carrying fuel, weapons, ammunition and rations, at 30-11N, 140-49E. A 1445, she sinks taking down four crewmen and 10 troops. The escorts counter-attack and drop 45 DCs, but PLUNGER suffers only slight damage. Subchaser CH-42 joins the escort from Chichi-Jima.

120 miles NNW of Chichi-Jima, Bonins. but at 2240, LtCdr (later Rear-Admiral) Charles O. Triebel's (USNA ’29) USS SNOOK (SS-279) fires five torpedoes and gets two hits that sink KOYO MARU at 28-49N, 141-13E. 1,046 troops and 34 crewmen are KIA. CH-42 rescues 142 survivors.

10 April 1944:
Removed from the Navy list.

Auhor's Notes:
[1] Not to be confused with KOYO MARU (6426 grt) or KOYO MARU (3021 grt).

Thanks go to Erich Muehlthaler of Germany.

-Bob Hackett

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