Omurosan Maru

Tabular Record of Movement

© 2008-2017 Bob Hackett and Peter Cundall.
Revision 9

17 March 1936:
Tama. Laid down at Mitsui’s shipyard.

17 October 1936:
Launched and named OMUROSAN MARU.

15 January 1937:
Completed and placed in service with Mitsui Bussan Kaisha.

Transports oil from Los Angeles to Japan.

10 January 1940:
Arrives at San Franscisco.

26 July 1941:
The United States places an embargo on oil exports to Japan to counter Japanese aggression in Asia.

12 January 1942:
Requisitioned by the IJA (allotted number is unknown).

16 January 1942:
Departs Kure.

21 January 1942:
Arrives at Mako.

25 January 1942:
Departs Mako.

30 January 1942:
Arrives at Kure.

6 February 1942:
Departs Kure.

8 February 1942:
Arrives at Yokkaichi.

11 February 1942:
Departs Yokkaichi.

13 February 1942:
Arrives at Tokuyama.

15 February 1942:
Departs Tokuyama.

16 February 1942:
Arrives at Kure.

18 February 1942:
Departs Kure.

20 February 1942:
Arrives at Yokkaichi.

24 February 1942:
Departs Yokkaichi.

28 February 1942:
Arrives at Mako.

3 March 1942:
Departs Mako.

6 March 1942:
Arrives at Kure.

17 March 1942:
Departs Tama.

18 March 1942:
Arrives at Kanokawa, Kure.

19 March 1942:
Departs Kanokawa.

24 March 1942:
Arrives at Mako.

26 March 1942:
Departs Mako.

1 April 1942:
Departs Kure for Hitose, Mako, Takao, Kure, Tainoura, Yokkaichi, Tokuyama, Kure, Tainoura, Yokkaichi, Mako, Tainoura, Yokkaichi, Tama, Kanokawa, Mako, Kure, Tainoura, Yokkaichi, Mako, Takao and Kure all supposedly within 22 days. It is very likely some of these are double ups from 16 January- refer above entries for pattern.

E 4 April 1942:
Arrives at Yokkaichi.

E 8 April 1942:
Departs Yokkaichi.

E 13 April 1942:
Arrives at Mako.

E 14 April 1942:
Departs Mako.

22 April 1942:
Arrives at Kanokawa, Kure.

23 April 1942:
Departs Kanokawa for Sasebo, then returns to Kure.

30 April 1942:
Arrives at Truk. Fleet oiler TOHO MARU takes on 2730 tons fuel from tanker NISSHIN MARU No. 2 and 1000 tons from tanker OMUROSAN MARU.

2 May 1942:
Departs Truk.

5 May 1942:
At 0800 arrives at Shortland.

7 May 1942:
At 0954 IRO, OMUROSAN MARU and destroyer UZUKI depart Shortland and head 100 Ri in a SW direction. Later at 1654 they arrive back at Shortland.

9 May 1942: The Battle of the Coral Sea:
After the Battle of the Coral Sea, the Attack Force returns to Rabaul.

Some ships sail to Shortland where they are refuelled by HOYO MARU, IRO and OMUROSAN MARU. OMUROSAN MARY refuels destroyer YUGURE and others. At 1400, OMUROSAN MARU supplies heavy oil to oiler IRO.

10 May 1942:
Departs Shortland.

11 May 1942:
Arrives at Rabaul.

19 May 1942:
Arrives at Kure.

22 May 1942:
Departs Kure for Chinkai, Sukumo, Kanokawa.

1 June 1942:
Arrives at Kure.

4 June 1942:
Departs Kure and transits the Bungo Straits.

9 June 1942:
Arrives at Saipan and departs port later that day.

12 June 1942:
Arrives at Chichijima.

21 June 1942:
Departs Chichijima.

23 June 1942:
Arrives at Yokkaichi.

24 June 1942:
Departs Yokkaichi.

27 June 1942:
Arrives at Sasebo and undergoes conversion at Sasebo Naval yard.

6 July 1942:
The conversion is completed. Departs Sasebo.

14 July 1942:
Arrives at Palembang.

16 July 1942:
Departs Palembang.

19 July 1942:
Arrives at Singapore.

26 July 1942:
Departs Singapore.

31 July 1942:
Arrives at Takao and departs later the same day and joins convoy No. 242 also consisting of two unidentified merchant ships escorted by auxiliary gunboat PEKING MARU.

4 August 1942:
At 0800 arrives at Moji.

5 August 1942:
Arrives at Marifu.

8 August 1942:
Departs Marifu.

9 August 1942:
Departs Kure.

18 August 1942:
Arrives at Palembang.

20 August 1942:
Departs Palembang.

22 August 1942:
Arrives at Singapore.

26 August 1942:
Departs Singapore.

27 August 1942:
Arrives at Palembang.

30 August 1942:
Departs Palembang.

1 September 1942:
Arrives at Singapore.

8 September 1942:
Departs Singapore in Convoy No. 630 consisting of OMUROSAN MARU and two unidentified merchant ships without escort.

11 September 1942:
Arrives at St Jacques.

12 September 1942:
Departs St Jacques in convoy No. 435 consisting of OMUROSAN MARU and five unidentified merchant ships without escort.

18 September 1942:
Arrives at Mako.

19 September 1942:
Departs Mako in convoy No. 264 consisting of OMUROSAN and KOSEI MARUs and four unidentified merchant ships without escort.

30 September 1942:
Arrives at Shimotsu.

2 October 1942:
Departs Shimotsu. Arrives at Tama later that day.

7 October 1942:
Departs Tama.

8 October 1942:
Arrives at Kure.

10 October 1942:
Departs Kure.

19 October 1942:
Arrives at Rabaul.

22 October 1942:
Departs Rabaul.

23 October 1942:
Arrives At Shortland. Refuels cruisers KINUGASA (153 tons) and CHOKAI (240 tons), light cruiser YURA (90 tons), destroyers AKIZUKI (140 tons), AKIKAZE (85 tons), SHIGURE (24 tons), SHIKINAMI (26 tons), HATSUYUKI (32 tons), AYANAMI (27 tons) and SHIRAYUKI (48 tons), and patrol boat PB-2 (255 tons).

24 October 1942:
Refuels light cruisers YURA (65 tons), TATSUTA (116 tons), destroyers AKATSUKI (48 tons), IKAZUCHI (49 tons), SHIGURE (38 tons), SHIRATSUYU (62 tons), AYANAMI (14 tons), HARUSAME (22 tons), YUDACHI (18 tons), ARIAKE (45 tons), MURASAME (22 tons), SAMIDARE (21 tons), ASAGUMO (47 tons), SHIKINAMI (14 tons), URANAMI (16 tons), HATSUYUKI (23 tons), AMAGIRI (18 tons), SHIRAYUKI (20 tons) and MOCHIZUKI (17 tons) and patrol boat PB-34 (65 tons).

25 October 1942:
Refuels minelayer WAKATAKA (40 tons), minesweeper W-20 (17 tons) and subchaser CH-1 (7 tons).

26 October 1942:
Refuels light cruiser SENDAI (560 tons), destroyers AKATSUKI (310 tons), IKAZUCHI (332 tons), AYANAMI (285 tons), HARUSAME (262 tons), YUDACHI (242 tons), MURASAME (255 tons), SAMIDARE (265 tons), ASAGUMO (162 tons), SHIKINAMI (261 tons), URANAMI (262 tons), HATSUYUKI (240 tons), AMAGIRI (83 tons), SHIRAYUKI (364 tons), MOCHIZUKI (59 tons), subchaser CH-1 (7 tons), minesweeper W-15 (19 tons), patrol boats PB-2 (43 tons) and PB-38 (60 tons).

27 October 1942:
Refuels light cruiser TATSUTA (52 tons), destroyers SHIGURE (396 tons), ARIAKE (160 tons) and seaplane carrier CHITOSE (719 tons). Later that day departs Shortland.

4 November 1942:
Arrives at Tarakan.

5 November 1942:
Departs Tarakan.

6 November 1942:
Arrives at Balikpapan.

10 November 1942:
Departs Balikpapan.

14 November 1942:
Arrives at Palau.

15 November 1942:
Departs Palau.

20 November 1942:
Truk. Refuels cruiser TAKAO (1105 tons) and battleships KONGO (3750 tons) and HARUNA (1565 tons).

21 November 1942:
Departs Truk with tanker NISSHIN MARU escorted by auxiliary gunboat CHOUN MARU.

22 November 1942:
In western Carolines near 10 nautical miles of Yoripikku (Eauripik Atoll), Namonuito Islands, CHOUN MARU is detached.

29 November 1942:
Arrives at Palembang.

1 December 1942:
Departs Palembang.

E 3 December 1942:
Arrives at Singapore.

4 December 1942:
At 1200, departs Singapore.

15 December 1942:
At 1800, arrives Tokuyama.

19 December 1942:
Departs Tokuyama.

20 December 1942:
Arrives at Osaka.

22 December 1942:
Departs Osaka.

28 December 1942:
The ship's owners are restyled as Mitsui Senpaku.

31 December 1942:
Arrives at Palembang.

2 January 1943:
Departs Palembang.

3 January 1943:
Departs Singapore.

4 January 1943:
Arrives at Singapore.

6 January 1943:
Departs Singapore.

17 January 1943:
Arrives at Yokkaichi.

21 January 1943:
Departs Yokkaichi.

22 January 1943:
Arrives at Tama.

27 January 1943:
Departs Tama.

5 February 1943:
Arrives at Palembang.

7 February 1943:
Departs Palembang.

9 February 1943:
Arrives at Singapore.

10 February 1943:
Departs Singapore.

21 February 1943:
At 1800, arrives at Amagasaki.

24 February 1943:
At Mitsui Tama for refit and repairs.

1 March 1943:
Departs Tama.

10 March 1943:
Arrives at Singapore.

15 March 1943:
At 1100 departs Singapore.

25 March 1943:
Arrives at Kawasaki.

30 March 1943:
Departs Kawasaki.

8 April 1943:
Arrives at Palembang.

10 April 1943:
Departs Palembang.

12 April 1943:
Arrives at Singapore.

15 April 1943:
Departs Singapore.

24 April 1943:
Arrives at Shimotsu.

30 April 1943:
Departs Shimotsu. Arrives later that day at Tama.

4 May 1943:
Departs Tama.

5 May 1943:
Arrives at Moji and departs later that day.

11 May 1943:
At 0900, arrives at Palembang.

16 May 1943:
Departs Palembang.

18 May 1943:
Arrives at Singapore.

22 May 1943:
Departs Singapore.

31 May 1943:
Arrives at Tokuyama.

3 June 1943:
Departs Tokuyama.

5 June 1943:
Arrives at Sasebo.

7 June 1943:
KIRISHIMA and KACHIDOKI MARUs, FUSHIMI MARU No. 3 and two unidentified merchant ships depart Moji in convoy No. 164 escorted by kaibokan ETOROFU. This same day, OMUROSAN MARU departs Sasebo and joins convoy No. 164.

10 June 1943:
Arrives at Mako.

13 June 1943:
Departs Mako.

15 June 1943:
Arrives at Singapore.

16 July 1943:
Arrives at Moji.

17 June 1943:
Departs Singapore.

23 June 1943:
Arrives at Palembang.

25 June 1943:
Departs Palembang.

27 June 1943:
Arrives at Singapore.

4 July 1943:
OMUROSAN MARU departs Singapore for Ujina in convoy No. 615 consisting of KINUGASA, TEIKO (ex-French D’ARTAGNAN), KACHIDOKI (ex-PRESIDENT HARRISON), AKI and MIIKE MARUs and tankers KIRISHIMA and KUROSHIO MARUs escorted by an unidentified warship.

5 July 1943:
Arrives at Miri.

6 July 1943:
At 1600 arrives at St Jacques.

8 July 1943:
OMUROSAN MARU departs St Jacques in the "J" convoy consisting of six unidentified merchant ships escorted by destroyer WAKATAKE.

11 July 1943:
Arrives at Mako and later that day at Takao.

17 July 1943:
Arrives at Ujina.

18 July 1943:
Arrives at Kudamatsu.

19 July 1943:
At 1100, OMUROSAN MARU departs Moji for Singapore in convoy HI-03 consisting of NANKAI, SEIA, NICHINAN and AWA MARUs escorted by second-class destroyer KARUKAYA.

22 July 1943:
Formosa Straits. At 0900, while enroute to Takao, fast passenger liner ASAMA MARU joins the convoy. At 2355, SEIA MARU is torpedoed and badly damaged by three of six torpedoes fired in a surface radar attack by LtCdr Eugene T. Sands' (USNA ’30) USS SAWFISH (SS-276) at 30-54N, 125-15E. She goes dead in the water. Later, the ship is taken in tow by NICHINAN MARU and together they head back to Japan.

23 July 1943:
In the morning, AWA and ASAMA MARUs are detached from the convoy and steam ahead.

25 July 1943:
At 1800 Convoy HI-03 consisting of NANKAI, AWA, ASAMA and tanker OMUROSAN MARU arrives at Takao. At Takao, the convoy is joined by cargo ship ARIMASAN MARU and kaibokan ETOROFU. KARUKAYA is detached to assist torpedoed SEIA MARU.

26 July 1943:
At 1600, the convoy departs Takao.

29 July 1943:
At 1650, surfaced German submarine U-511 inbound from France encounters convoy HI-03 bound for Singapore. The sight of the submarine causes confusion aboard OMUROSAN MARU. Her gunners fire three shells at U-511, before the mistake is cleared up. The skipper of ETOROFU (convoy commander) inspects U-511 and personally apologizes for the attack.

1 August 1943:
At 1400, convoy HI-03 arrives at Singapore.

5 August 1943:
At 1400, convoy HI-04 departs Singapore for Moji consisting of oilers OMUROSAN and ITSUKUSHIMA MARUs and two unidentified fast ships escorted by kaibokan ETOROFU.

10 August 1943:
Arrives at Manila.

11 August 1943:
At 1700, departs Manila. At 2030, ETOROFU discovers a surfaced submarine 5,000 yards ahead and opens fire with her forward gun forcing the submarine to submerge. ETOROFU drops depth charges for no visible results. For the next two days, ETOROFU continues to hunt in the area without success while the convoy steams ahead unescorted. [1]

E 14 August 1943:
ETOROFU returns to Manila. The convoy arrives at Moji the next day.

16 August 1943:
Arrives at Mutsure.

17 August 1943:
Departs Mutsure.

18 August 1943:
Arrives at Shimotsu.

20 August 1943:
Departs Shimotsu and later that day arrives at Tama. Undergoes engine repairs.

24 August 1943:
Departs Tama and later that day arrives at Moji.

25 August 1943:
At 0900, OMUROSAN MARU departs Moji for Singapore in convoy HI-07 consisting of oilers ITSUKUSHIMA, GOYO (ex-cargo), NAMPO and NANEI MARUs and cargo-passenger ship USSURI MARU escorted by kaibokan ETOROFU.

29 August 1943:
Arrives at Takao.

30 August 1943:
Arrives at Mako. ETOROFU is detached and replaced by kaibokan SADO.

1 September 1943:
Released from IJA service, then requisitioned by the IJN and assigned to the Kure Naval District.

8 September 1943:
Arrives at Saigon.

9 September 1943:
Departs Saigon.

12 September 1943:
Arrives at Singapore.

22 September 1943:
Arrives at Amagasaki.

24 September 1943:
Departs Amagasaki.

27 September 1943:
Arrives at Tama for repairs.

21 October 1943:
Departs Tama and arrives at Hiro that day.

23 October 1943:
Departs Hiro and arrives at Tokuyama that day.

27 October 1943:
Departs Tokuyama and later that day arrives at Moji.

28 October 1943:
At 1607, OMUROSAN MARU departs Moji in convoy HI-17 consisting of ASAMA MARU and tankers ITSUKUSHIMA and TATEKAWA MARUs, transport SAKITO MARU and landing craft depot ship AKITSU MARU escorted by destroyer FUYO and kaibokan ETOROFU.

30 October 1943:
At 0430 SAKITO MARU at 31.55N 123.10E collides with passenger ship SHANGHAI MARU part of MO-902 convoy bound from Shanghai to Kyushu. SHANGHAI MARU is hit low in the bow and flooding can't be checked. At 0516 the ship sinks. The convoy including SAKITO MARU continues its voyage south.

1 November 1943:
At 1115, arrives at Takao.

2 November 1943:
At 1500, OMUROSAN MARU departs Takao in convoy HI-17 consisting of transports ASAMA and KACHIDOKI (ex-PRESIDENT HARRISON) MARUs and fleet oiler TAKASAKI, tankers TATEKAWA, OTORISAN, OTOWASAN, TARAKAN, ITSUKUSHIMA MARUs, landing craft depot ship AKITSU MARU and transport SAKITO MARU escorted by destroyer FUYO (partway while en route) and kaibokan MATSUWA and ETOROFU.

4 November 1943:
At 1900 arrives at Manila. AKITSU MARU and FUYO detach.

5 November 1943:
At 1430 the convoy departs Manila. FUYO joins as an additional escort.

6 November 1943:
At 1830 ETOROFU is detached from the convoy and begins a submarine hunt.

11 November 1943:
At 1000, arrives at Singapore.

15 November 1943:
At 1300, OMUROSAN MARU departs Singapore in convoy HI-18 consisting of tankers ITSUKUSHIMA and TATEKAWA MARUs and two unidentified merchant ships escorted by destroyer FUYO.

23 November 1943 :
At 1400, arrives at Manila. FUYO is replaced by destroyer KURETAKE.

24 November 1943:
At 1518, departs Manila.

28 November 1943:
At 0655, arrives at Moji.

29 November 1943:
Arrives at Amagasaki.

1 December 1943:
OMUROSAN MARU departs Moji in Part 1 of convoy HI-23 consisting of fleet oiler TAKASAKI, oilers ICHIU and RYUEI MARUs and transports AKI and NOSHIRO MARUs escorted by destroyer NAMIKAZE. [2]

5 December 1943:
The second echelon of convoy HI-23 departs Moji consisting of oilers TATEKAWA, ITSUKUSHIMA and BOKUEI MARUs, with fleet oilers SUNOSAKI and OSE (ex-Dutch GENOTA), all escorted by OSE.

7 December 1943:
OMUROSAN departs Takao in convoy HI-23 consisting of fleet oilers TAKASAKI, SUNOSAKI and OSE, merchant tankers ICHIU, ITSUKUSHIMA, TATEKAWA, RYUEI, BOKUEI and cargo passenger ships NOSHIRO and AKI MARUs plus GOYO and ICHIYO MARUs escorted by destroyer NAMIKAZE and kaibokan KANJU.

10 December 1943:
Arrives at St. Jacques, Indochina where the convoy is disbanded.

21 December 1943:
OMUROSAN MARU and tankers TATEKAWA and ITSUKUSHIMA MARUs and IJN transport NANKAI MARU depart Singapore for Moji in convoy SA-20 escorted by kaibokan SHIMUSHU and torpedo boat KARI.

27 December 1943:
Arrives at Takao. Both escorts are detached and destroyer SHIOKAZE takes over escort of the convoy.

28 December 1943:
Departs Takao.

1 January 1944:
Arrives at Moji.

5 January 1944:
Arrives at Tokuyama.

8 January 1944:
Departs Tokuyama.

11 January 1944:
At 0600, OMUROSAN MARU departs Moji for Singapore in convoy HI-31 consisting of tankers TATEKAWA, ITSUKUSHIMA, HOKUROKU, GENYO and possibly KUROSHIO MARUs escorted by light carrier CHITOSE and destroyers AMATSUKAZE and YUKIKAZE.

16 January 1944:
N of the Spratly Islands. AMATSUKAZE is torpedoed by USS REDFIN (SS-272) and the convoy presumes she has been sunk. She is adrift for six days until discovered by a patrol plane.

20 January 1944:
Convoy HI-31 arrives at Singapore.

25 January 1944:
At 0730, OMUROSAN MARU departs Singapore for Moji in convoy HI-32 consisting of tankers TATEKAWA, ITSUKUSHIMA, KINUGASA, HOKUROKU, GENYO and KUROSHIO MARUs escorted by escort carrier CHITOSE and destroyer YUKIKAZE.

E 28 January 1944:
Kaibokan MIYAKE joins the convoy from Manila.

1 February 1944:
A patrol plane from the CHITOSE spots a small drifting boat ahead of the convoy, about 60 nm east of Okinawa. MIYAKE is detached to investigate. When closing it becomes clear that the small boat is actually a landing barge with more than 100 survivors from the TARUSHIMA MARU 4865gt. MIYAKE takes over 54 survivors, followed by YUKIKAZE which takes over the remaining 57 survivors.

4 February 1944:
CHITOSE is detached for Sasebo. At 1100, convoy HI-32 arrives at Moji. Later that day arrives at Kudamatsu.

7 February 1944:
Departs Kudamatsu and later that day arrives at Tokuyama.

14 February 1944:
Departs Tokuyama and later that day arrives at Moji.

16 February 1944:
At 0600, OMUROSAN MARU departs Moji for Singapore in convoy HI-45 consisting of tankers TATEKAWA, ITSUKUSHIMA and KUROSHIO MARUs, cargo liner ARIMASAN MARU, IJA landing craft depot ship TAMATSU MARU and an unidentified ship escorted by destroyer SHIOKAZE.

20 February 1944:
Destroyer SHIOKAZE is detached.

21 February 1944:
KUROSHIO MARU suffers engine trouble and is detached for Takao, Formosa.

22 February 1944:
Kaibokan MIYAKE joins the escort.

23 February 1944:
TAMATSU MARU is detached for Manila. Destroyer SHIOKAZE rejoins the escort.

27 February 1944:
At 1700, arrives at Singapore.

28 February 1944:
Transfers from Seletar to Keppel Harbour, within Singapore.

11 March 1944:
At 0730, OMUROSAN MARU departs Singapore for Moji in convoy HI-48 consisting of tankers OTOWASAN, TATEKAWA, ITSUKUSHIMA, SEIYO, NICHIEI and KUROSHIO MARUs, transport/cargo liners AWA, TEIA (ex-French ARAMIS), SANUKI and HOKUROKU MARUs and two unidentified ships escorted by kaibokan MIYAKE, SHIMUSHU and IKI.

14 March 1944:
Gulf of Thailand. SANUKI MARU is damaged by a mine or torpedo. The damage causes her to drop out of the convoy on the coast. At 1700, ETOROFU arrives at Van Phong Bay, French Indochina.

15 March 1944:
At 1100, departs Van Phong Bay.

18 March 1944:
At 0114, HOKUROKU MARU is hit by three torpedoes fired by LtCdr (later Cdr) Lowell T. Stone's (USNA ’29) USS LAPON (SS-260). One hit causes an induced explosion. HOKUROKU MARU sinks about a minute later with 6,700-tons of bauxite and 600-tons of crude oil at 19-24N, 116-50E. Eight of 256 military passengers, 25 guards and 55 crewmen, including Captain Itokawa Suetada (36) (ex-XO of armoured cruiser HIRADO), are KIA. Itokawa is promoted Rear Admiral posthumously. Later that day, KASHII MARU joins the convoy.

19 March 1944:
At 0600, kaibokan SHIMUSHU runs aground, but is refloated later that day. At 1600, the convoy arrives at Takao.

20 March 1944:
At 1300, departs Takao.

25 March 1944:
At 0500, arrives at Moji.

1 April 1944:
OMUROSAN MARU departs Moji for Singapore in convoy HI-57 consisting of tankers ITSUKUSHIMA, OTOWASAN and RYOEI MARUs, IJA landing craft depot ships SHINSHU and MAYASAN MARUs and three unidentified ships (likely tankers SHINCHO and ZUIHO MARUs and another) escorted by escort carrier KAIYO, kaibokan IKI, SHIMUSHU, CD-8, CD-9 and torpedo boat SAGI.

2 April 1944:
The convoy encounters extremely severe weather and returns to Moji.

3 April 1944:
At 0600, the unchanged convoy departs Moji.

7 April 1944:
At 1450, arrives at Takao.

8 April 1944:
At 1000, departs Takao. Shelters briefly in Chechung Bay, before proceeding later that day.

12 April 1944:
At 1930 arrives at Camranh Bay.

13 April 1944:
At 1200, departs Camranh Bay.

16 April 1944:
At 1240, arrives at Singapore.

21 April 1944:
At 0700, OMUROSAN MARU departs Singapore for Moji in convoy HI-58 consisting of oilers ITSUKUSHIMA, RYOEI, OTOWASAN and probably ZUIHO MARUs, transport KACHIDOKI MARU (ex PRESIDENT HARRISON), IJA landing craft depot ships SHINSHU and MAYASAN MARUse scorted by escort carrier KAIYO and kaibokan IKI, ETOROFU, SHIMUSHU, CD-8 and CD-9.

24 April 1944:
E of Saigon. USS ROBALO (SS-273) under LtCdr Manning M. Kimmel (USNA ’35) (son of Admiral H. E. Kimmel, former CINCPACFLT at Pearl Harbor) attempts to attack the convoy, but is sighted by a Nakajima B5N2 "Kate” of the 931st NAG detachment from KAIYO. The B5N2 drops one 250-kg depth-charge on the submerged submarine and causes medium damage.

3 May 1944:
HI-58 arrives at Moji.

29 May 1944:
At 0600, OMUROSAN MARU departs Moji in convoy HI-65 consisting of fleet oiler SHIRETOKO and tankers ITSUKUSHIMA, ZUIHO and TOHO MARUs, cargo liners ARIMASAN, MANILA, KASHII and TATSUWA MARUs and IJA landing craft depot ship SHINSHU MARU escorted by escort carrier KAIYO, light cruiser KASHII, kaibokan AWAJI, CHIBURI, CD-11 and CD-19 and subchaser CH-60. Light minelayer TSUBAME departs Moji later, catches up with the convoy, and joins the escort.

2 June 1944:
Bashi Strait. Kaibokan AWAJI is torpedoed by LtCdr (later Captain) Enrique D. Haskins' (USNA ’33) new USS GUITARRO (SS-363) and sinks near Yasho Island at 22-34N, 121-15E. Kaibokan CHIBURI and CD-19 rescue the survivors, but several die of their wounds.

LtCdr (later Captain) Albert L. Raborn's (USNA ’34) USS PICUDA (SS-382) fires two torpedoes at ARIMASAN MARU that cause her to collide with SHINSHU MARU's stern. This causes a depth charge explosion that kills about 70 men and causes rudder damage. KASHII takes SHINSHU MARU in tow. ARIMASAN MARU is lightly damaged in the attack and heads for Keelung, Formosa with KASHII and SHINSHU MARU.

3 June 1944:
Arrives at Keelung, Formosa.

4 June 1944:
Departs Keelung. Later that day, arrives at Takao, Formosa. KAIYO rejoins the convoy after brief stop at Saei (Tsoying) Formosa. Tanker JINEI MARU joins the convoy at sea. ARIMASAN, MANILA, KASHII, TATSUWA and SHINSHU MARUs are all detached for Manila.

8 June 1944:
Off Indochina. At 0906(H), KAIYO is sighted by Cdr (later Admiral/CINCPACFLT) John S. McCain Jr.’s (USNA ’31) USS GUNNEL (SS-253) at 11-59N, 112-29E. GUNNEL’s SJ radar picks up an aircraft at 24 miles. The Officer of the Deck (OOD) dives prematurely and contact with the convoy is lost and never regained.

12 June 1944:
At 1350, arrives at Singapore.

17 June 1944:
At 0400, OMUROSAN MARU departs Singapore in convoy HI-66 consisting of transport/cargo liners SANUKI, HOKKAI and AWA MARUs escorted by escort carrier KAIYO, light cruiser KASHII and kaibokan CHIBURI, CD-7 and CD-11. The convoy hugs the continental coast avoiding deep water as much as possible.

26 June 1944:
At 1300, arrives at Moji.

27 June 1944:
Arrives at Hikoshima.

29 June 1944:
Departs Hikoshima.

1 July 1944:
Arrives at Moji.

13 July 1944:
OMUROSAN MARU departs Moji for Singapore in convoy HI-69 consisting of escort carriers KAIYO and TAIYO, each loaded with aircraft for Luzon, tankers KOEI, HAKKO, OTOWASAN, KUROSHIO, HARIMA, SERIA, TENEI MARUs and transports KIMIKAWA, AKI, ASAMA, SAIGON, KACHIDOKI (ex-PRESIDENT HARRISON), MANKO MARUs and possibly MANJU MARU escorted by escort carrier SHINYO, light cruiser KASHII and kaibokan CHIBURI, SADO, CD-7 and CD-17. SHINYO's aircraft conduct patrols. OMUROSAN MARU carries a deck cargo of 120 men, vehicles and munitions.

18 July 1944:
Near Takao, Formosa. About 0600, LtCdr John J. Flachsenhar's (USNA ’35) USS ROCK (SS-274) fires four torpedoes at HARIMA MARU, but misses. Cdr Alan Banister's (USNA ’28) USS SAWFISH (USS 276) fires nine torpedoes at the convoy. HARIMA MARU is hit by a single torpedo, but she remains able to steam. At 1055, LtCdr Roger M. Keithy's (USNA ’35) USS TILEFISH (SS-307) torpedoes and heavily damages CD-17. The convoy continues to Manila without stopping at Takao as originally planned (less MANKO MARU detached the day before and damaged HARIMA MARU and CD-17 that put into Takao).

20 July 1944:
At 2100, arrives at Manila. KAIYO and TAIYO begin unloading aircraft.

25 July 1944:
At 0530, OMUROSAN MARU departs departs Manila for Singapore in convoy HI-69 that now consists of KIMIKAWA, HAKKO, OTOWASAN, KUROSHIO, SERIA, KACHIDOKI (ex-PRESIDENT HARRISON) and TENEI MARUs escorted by escort carrier SHINYO, light cruiser KASHII and kaibokan SADO, CHIBURI, CD-7, CD-9, CD-13 and CD-19.

31 July 1944:
Arrives at Singapore.

4 August 1944:
At 2100, OMUROSAN MARU departs Singapore for Moji in convoy HI-70 consisting of oilers SERIA, KUROSHIO, OTOWASAN and HAKKO MARUs and MANJU, KINUGASA, ARIMASAN MARUs screened by SHINYO, KASHII, destroyer SHIMOTSUKI and kaibokan CHIBURI, SADO, CD-13 and CD-19.

12 August 1944:
SADO is detached to hunt an enemy submarine.

15 August 1944:
HI-70 arrives at Moji at 1430.

25 August 1944:
OMUROSAN MARU departs Moji for Singapore in convoy HI-73 consisting of IJA landing craft depot ship KIBITSU MARU, ex-armed merchant cruiser GOKOKU MARU, ex-seaplane tenders KAGU and SANUKI MARUs, tankers TOHO, OTOWASAN, TAIHO, FUJISAN, HAKKO, AMATO, TOA and KUROSHIO MARUs and fleet storeship IRAKO escorted by escort carrier UNYO, light cruiser KASHII and kaibokan CHIBURI, CD-1, CD-13, CD-19, CD-21 and CD-27.

Later that day, the convoy is joined briefly by transports MIZUHO, ARABIA and KOKURYU MARUs and tanker MANEI MARU.

26 August 1944:
At 0900, MIZUHO, ARABIA and KOKURYU MARUs are ordered away because of excessive smoke. CD-1 also detaches for Sasebo. MANEI MARU remains at Kyushu because of engine problems.

29 August 1944:
Arrives at Takao, Formosa. Departs that same day and arrives at Saei/Tsoying (near Takao).

1 September 1944:
Off Saei, Formosa. The convoy splits. KIBITSU, GOKOKU and KAGU MARUs (and probably IRAKO) head for Manila. The remaining ships head for Singapore.

3 September 1944:
TOA MARU strikes a mine S of Saigon and is lightly damaged, but able to continue.

5 September 1944:
At 0954, arrives at Seletar, Singapore.

11 September 1944:
At 1100, OMUROSAN MARU departs Seletar for Moji in convoy HI-74 consisting of tankers AZUSA, OTOWASAN, HARIMA and HAKKO MARUs escorted by escort carrier UNYO, light cruiser KASHII (F) and kaibokan CHIBURI, CD-13, CD-19, CD-21 and CD-27.

16 September 1944:
At 2231, OMUROSAN MARU is hit by a torpedo fired by Cdr (later Rear Admiral) Charles E. Loughlin's (USNA ’33) USS QUEENFISH (SS-393). At 2334, oiler AZUSA MARU is hit by two of a salvo of six bow torpedoes fired by Cdr (later Rear Admiral) Eugene B. Fluckey's (USNA ’35) USS BARB (SS-220). AZUSA MARU blows up and sinks with all hands (100 crewmen and passengers). UNYO is hit by other torpedoes in Fluckey's salvo and settles aft, her crew set to work, and it seemed she might be saved. At 0142 she radios "Torpedo attack, two torpedoes, damage sustained." Sinking was not expected. However, the sea conditions worsened, pounding hard at the fantail, and collapsing the emergency reinforcements to the bulkheads. By 0730 she was listing heavily to starboard, and the order was given to abandon ship. At 0755 UNYO sank by the stern in position 19-10'N, 116-35'E (Radio notice at 0805 gives slight variant of 19-08'N, 116-36'E.") Working hard in the stormy seas, escorts CHIBURI and CD-27 rescue 55 officers and 706 men, but her CO, Captain (Rear Admiral posthumously) Kimura Kozo (Ikuzo) (49) and more than 900 crewmen and passengers are lost as are 48 aircraft, including a cargo of 36 Imperial Army planes UNYO was carrying back to Japan for overhaul and repairs.

23 September 1944:
At 1700, arrives at Moji.

1 October 1944:
At 0800, OMUROSAN MARU departs Moji for Singapore in convoy HI-77 consisting oilers OTOWASAN, ARITA, ITSUKUSHIMA, AKANE, TAIHO and KAIHO MARUs, transports MANJU and KINUGASA, and ORYOKU MARUs, German submarine supply ship QUITO (KITO-GO) and an unidentified vessel escorted by kaibokan CHIBURI and CD-19, CD-21 and CD-27. Shelters overnight in Arikawa Bay.

2 October 1944:
Departs Arikawa Bay.

5 October 1944:
Arrives at Takao. Before departing later the same day, HI-77’s escort is bolstered by inclusion of kaibokan ETOROFU and SHONAN.

6 October 1944:
250 miles W of Manila. After patrolling the Luzon Strait, a wolfpack consisting of LtCdr (later Captain) Arnold H. Holtz’s (USNA ’31) USS BAYA (SS-318), LtCdr Henry D. Sturr’s (USNA ’33) USS BECUNA (SS-319) and LtCdr Francis W. Scanland, Jr’s (USNA ’34) USS HAWKBILL (SS-366) heads through the South China Sea towards Fremantle, Australia.

About 1400, LtCdr (later Captain) James B. Grady's USS WHALE (SS-239) fires five torpedoes that all hit, and sinks oiler AKANE MARU. 747 Army Management Branch Cadets and Railway Officials and 63 crewmen are killed. At 1757, Cdr (later Rear Admiral) Charles W. Wilkins' (USNA ’24) USS SEAHORSE (SS-304) torpedoes and sinks CD-21 at 19-45N, 118-22E. As the stern part sinks, the kaibokan's depth charges go off, killing any survivors in the water. Her entire complement of 170 men is lost.

7 October 1944:
At about 2200, KINUGASA MARU carrying 1,000 port service workers and ammunition,is hit by three more torpedoes. At 2224, USS HAWKBILL, running on the surface, fires four torpedoes and gets three hits followed by an ammo explosion. LtCdr Holtz’s USS BAYA also torpedoes and sinks KINUGASA MARU. 33 crewmen and 10 passengers are KIA.

12 October 1944:
At 1500, the remainder of HI-77 arrives at Singapore.

16 October 1944:
Yokohama. Combined Fleet Headquarters, Keio University. Chief of Staff Vice Admiral Kusaka Ryunosuke (41)(former CO of AKAGI) releases a dispatch that assigns oilers OMUROSAN, NICHEI, YUHO, RYOEI and MANEI (BANEI) MARUs to Vice Admiral Kurita Takeo's (38)(former CO of KONGO) First Striking Force's 1st Supply Force with oiler ITSUKUSHIMA MARU, minelayer YURIJIMA, kaibokan CHIBURI, CD-19 and CD-27 and minesweeper W-34. Later, oilers HAKKO and NIPPO MARUs are also assigned to Kurita's force.

17 October 1944:
Vice Admiral Kurita orders OMUROSAN and NIPPO MARUs to proceed to Brunei, Borneo with YURIJIMA and CD-27.

20 October 1944:
Departs Singapore.

22 October 1944:
Arrives at Brunei. At 0800, Kurita's Striking Force steams for Leyte Gulf via the Sibuyan Sea and San Bernardino Strait. Kurita orders Vice Admiral Nishimura Shoji's (39)(former CO of HARUNA) BatDiv 2, cruiser MOGAMI and four destroyers to sortie through Surigao Strait to Leyte Gulf to envelop the U.S. invasion forces. Vice Admiral Shima Kiyohide's (39)(former CO of OI) Fifth Fleet from the Pescadores is also to sortie through Surigao Strait to Leyte Gulf.

25 October 1944: Operation "SHO-I-GO" (Victory) - The Battle of Leyte Gulf:
In the course of battle, Kurita loses superbattleship MUSASHI, cruisers ATAGO, MAYA, CHOKAI, CHIKUMA and SUZUYA with KUMANO, MYOKO and TAKAO damaged severely. Several destroyers are also lost and damaged. Nishimura loses old battleships FUSO and YAMASHIRO and cruiser MOGAMI. Shima arrives behind the carnage wrought on Nishimura's force and wisely reverses his small force's course away from certain destruction.

28 October 1944:
Arrives at Brunei. At 0050, minesweeper W-34 lies alongside and loads heavy oil. From 1230 refuels destroyers ISOKAZE and YUKIKAZE. At 2330 refuels destroyer URAKAZE.

29 October 1944:
OMUROSAN, YUHO and HAKKO MARUs refuel battleships HARUNA, KONGO and NAGATO, cruiser HAGURO, light cruiser YAHAGI and DesDiv 17’s HAMAKAZE, URAKAZE, ISOKAZE and YUKIKAZE. YUHO MARU refuels YAMATO.

30 October 1944:
Departs Brunei.

1 November 1944:
Arrives at Manila.

3 November 1944:
Departs Manila.

6 November 1944:
Arrives at Labuan and departs later that day.

9 November 1944:
Arrives at Singapore.

13 November 1944:
Departs Singapore.

15 November 1944:
Arrives at Brunei. Refuels battleships YAMATO, NAGATO, KONGO and heavy cruiser ASHIGARA.

17 November 1944:
Departs Brunei and later that day arrives at Miri.

18 November 1944:
Departs Miri.

20 November 1944:
Arrives at Singapore.

21 November 1944:
Transfers to Pulau Bukum.

22 November 1944:
Transfers to Tjombol Island.

23 November 1944:
Transfers back to Singapore.

8 December 1944:
Moves from Pulau Bukum to Singapore.

12 December 1944:
At 1600, OMUROSAN MARU departs Singapore in convoy HI-82 consisting of tankers OTOWASAN, ARITA, PALEMBANG and HASHIDATE MARUs escorted by kaibokan ETOROFU, SHONAN, KUME, CD-9 and CD-19. OTOWASAN MARU carries a cargo of gasoline.

14 December 1944:
Arrives at Panjang Island.

15 December 1944:
Departs Panjang Island.

17 December 1944:
Arrives at Camranh Bay, Indochina.

19 December 1944:
Departs Camranh Bay.

22 December 1944:
25 miles E of Quang Ngai, Indochina. At 0550, OMUROSAN, OTOWASAN and ARITA MARUs are torpedoed by LtCdr (later Captain-Ret) George W. Grider's (USNA ’36) USS FLASHER (SS-249). All three tankers burst into flames. At 0550, after being hit amidships by two torpedoes, OMUROSAN MARU sinks at 15-07N, 109-05E. Two crewmen are KIA.

OTOWASAN (63 crewmen, 56 troops and one passenger KIA) and ARITA (57 crewmen KIA) MARUs also sink.

10 February 1945:
Removed from the Navy List.

Authors' Notes:
[1] The submarine probably was USS KINGFISH (SS-234).

[2] Convoy HI-23 was Japan's first carrier escorted convoy.

Thanks for assistance goes to Sander Kingsepp of Estonia and to Mr. Gilbert Casse of France.

Photo credit goes to Dan Wheeler collection via Ron Wolford and Gilbert Casse.

Thanks go to Toda Gengoro of Japan for information in Revision 2.

- Bob Hackett and Peter Cundall.

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