YUSOSEN!
(HOZAN MARU sistership of UNKAI MARU No. 12, in wartime)
IJN UNKAI MARU No. 12:
Tabular Record of Movement
© 2017-2018 Berend van der Wal, Gilbert Casse and Peter Cundall
Revision 1
E 1943:
Laid down by Osaka Zosensho K.K. shipyard for Nakamura Kisen K.K. as a Standard Peacetime (C) Type 2,745 GRT cargo ship.
June 1943:
Completed and named UNKAI MARU No. 12.
20 August 1943:
Completed and registered at Kobe.
6 October 1943:
Departs Kobe in convoy No. 8006 also consisting of ore carrier DAIZEN MARU and transport KACHIDOKI MARU (ex-US PRESIDENT HARRISON) with unknown escort. The ships sail at 8.5 knots. UNKAI MARU No. 12 is bound for Yokohama.
12 October 1943:
Requisitioned by the IJN and registered as a general requisitioned transport (Ippan Choyosen) attached to the Yokosuka Naval District.
18 October 1943:
At 1300, departs Yokosuka in convoy No. 7018B also consisting of SHINWA, ASAHISAN and YAMAHAGI MARUs escorted by minesweeper W-27.
20 October 1943:
At 0400, W-27 is detached and heads for Kobe.
21 October 1943:
Arrives at Moji.
22 October 1943:
Departs Moji in second part of convoy No. 108 also consisting of SHINWA, KOSHU (2612 gt), MADRAS, TOTTORI, HASSHU MARUs and six unidentified merchant ships escorted by auxiliary gunboat CHOHAKUSAN MARU.
23 October 1943:
Arrives at Tomie.
25 October 1943:
Departs Tomie.
30 October 1943:
Arrives at Takao, Formosa (now Kaoshiung, Taiwan).
3 November 1943:
Departs Takao and arrives at Mako, Pescadores later that day.
4 November 1943:
Departs Mako in convoy No. 335 also consisting of NORFOLK MARU and three unidentified merchant ships without surface escort.
9 November 1943:
Arrives at St. Jacques, French Indochina (now Vung Tau, Vietnam).
12 November 1943:
Departs St. Jacques in convoy No. 524 also consisting of SANTOS and NORFOLK MARUs.
15 November 1943:
At 1240 arrives at Singapore.
20 November 1943:
Departs Singapore for Sabang, Sumatra, Netherlands East Indies (NEI) in a convoy also consisting of three unidentified merchant ships (probably tankers en route to Belawan or Pankalan Susu) escorted by two unidentified auxiliaries. One of these was likely auxiliary subchaser KYO MARU No. 1.
22 November 1943:
At 1235, in 04-42N, 98-17E UNKAI MARU No. 12 is missed by two torpedoes that pass ahead of the ship.
28 November 1943:
While en route from Sabang to Car Nicobar at 1733, UNKAI MARU No. 12 is attacked and missed by HMS TRESPASSER in 08-50N, 93.07E. The ship later returns from Car Nicobar, Andamans to Sabang.
3 December 1943:
At 1700, departs Sabang.
5 December 1943:
At 1500, arrives at Sibolga, Sumatra.
8 December 1943:
Departs Sibolga.
9 December 1943:
Arrives at Padang, Sumatra.
12 December 1943:
Departs Padang.
14 December 1943:
Arrives at Bengkulu. Sumatra.
17 December 1943:
Departs Bengkulu.
19 December 1943:
Arrives at Banka Island, east of Sumatra.
20 December 1943:
Departs Banka and returns there later that day.
21 December 1943:
Departs again Banka.
22 December 1943:
Arrives at Singapore.
14 January 1944:
At 0800, departs Singapore.
24 January 1944:
Departs Singapore.
28 January 1944:
Arrives at Car Nicobar.
1 February 1944:
Departs Car Nicobar.
5 February 1944:
Arrives at Singapore.
8 February 1944:
Departs Singapore.
8 February 1944:
Arrives at Bintang, Riau Archipelago, NEI.
9 February 1944:
Departs Bintang and arrives at Singapore later that day.
13 February 1944:
Departs Singapore in convoy SHISA-03 also consisting of three unidentified merchant ships without surface escort.
17 February 1944:
Arrives at St. Jacques.
18 February 1944:
Departs St. Jacques and arrives at Saigon, French Indochina (now Ho Chi Minh City, Vietnam) later that day.
20 February 1944:
Departs Saigon and arrives at St. Jacques later that day.
23 February 1944:
Departs St. Jacques in convoy SATA-06 also consisting of SAINEI and KOAN MARUs and six unidentified merchant ships escorted by submarine chaser CH-41.
24 February 1944:
Arrives at Cam Ranh Bay, French Indochina.
1 March 1944:
Departs Cam Ranh Bay and arrives at Van Phong Bay, French Indochina later that day.
4 March 1944:
Departs Van Phong Bay.
12 March 1944:
Arrives at Takao.
15 March 1944:
At 1200, departs Takao for Moji in convoy TAMO-11 also consisting of cargo/transports ASAHI, ASAHISAN, BRAZIL, HINODE, KENZUI, KENNICHI, KENWA, KOAN (4305 GRT), KOHO, KOTO, MANILA, MANKO, MUTSU, SHINNO, SORACHI, TARUYASU, TAITO and BELGIUM MARUs and oilers NITTETSU, SAN DIEGO, SANKO (YAMAKO), TACHIBANA and TAKETSU (BUTSU) MARUs and OGURA MARU No. 1 escorted by destroyers NOKAZE and SHIGURE, minesweeper W-17 and subchasers CH-37 and CH-38.
16 March 1944:
At 1600, TOYO (2704 GRT) and TEIKO (ex-Vichy French D’ARTAGNAN) MARUs join the convoy.
21 March 1944:
At 0430, MANKO, ASAHI, and TOYO MARUs are detached from the convoy. At 1200, convoy TAMO-11 arrives at Nagasaki.
22 March 1944:
Detached with ASAHISAN and KOAN MARUs and arrives at Karatsu Bay. Departs there and arrives at Wakamatsu later that day.
27 March 1944:
Departs Wakamatsu.
28 March 1944:
Arrives at Sasebo.
12 April 1944:
Departs Sasebo.
13 April 1943:
Arrives at Mutsure.
14 April 1944:
Departs Mutsure and arrives at Chinkai, Chosen (now Jinhae, South Korea) later that day.
16 April 1944:
Departs Chinkai.
19 April 1944:
Arrives at Ssu Chiao Shan (Raffes Island, now Sijiao island, Shengsi, Zhoushan), China.
21 April 1944:
Departs Ssu Chiao Shan in convoy MOTA-17 (“Take” (Bamboo)) convoy also consisting of transports KAZUURA, MITSUKI, BRAZIL, TENSHINZAN (AMATSUSAN), ADEN, TAJIMA, YOZAN, MANSHU, FUKUYO, TEIKAI (ex German FULDA), KANAN, TEIKA (ex-French CAP VARELLA) MARUs and YOSHIDA MARU No. 1 and an unidentified merchant ship escorted by minelayer SHIRATAKA (F), destroyers ASAKAZE, SHIRATSUYU, KURI and FUJINAMI, kaibokan CD-20, CD-22 and KURAHASHI, minesweeper W-22, subchasers CH-37, CH-38, gunboats UJI, ATAKA and auxiliary minesweeper TAMA MARU No. 7. The convoy carries troops of the IJA's 32nd and 35th divisions from China to New Guinea via Manila.
26 April 1944:
At about 0600, LtCdr (later Rear Admiral-Ret) Thomas M. Dykers' (USNA ’27) USS JACK (SS-259) makes a radar-assisted surface attack on the convoy. Dykers torpedoes and sinks 5,245-ton YOSHIDA MARU No. 1 at 18-06N, 119-40E. She takes down 2,586 men of the 3800 men on board of the IJA's 32nd Division, 213th Infantry Regiment and 61 crewmen and two passengers. W-22 counterattacks with depth charges.
27 April 1944:
Arrives at Manila, Philippines in the “Take” convoy.
29 April 1944:
Departs Manila and arrives at Cavite, Philippines later that day.
30 April 1944:
Departs Cavite and arrives at Manila later that day.
1 May 1944:
At 0400, departs Manila in a convoy also consisting of KANAN, JUKO, and JAMBI MARUs escorted by minesweeoer W-101.
4 May 1944:
Detached from the convoy and heads towards Zamboanga, Mindanao, Philippines.
5 May 1944:
Arrives at Zamboanga.
11 May 1944:
Scheduled to depart Zamboanga for Davao, Mindanao, Philippines escorted by W-22 and auxiliary subchaser CH-11.
12 May 1944:
At 0545, departs Zamboanga escorted by W-22 and auxiliary subchaser Cha-12. They arrive at 1828, at Igat Bay, Mindanao, Philippines.
13 May 1944:
At 0555, departs Igat Bay and at 1744, arrives at Polloc, Mindanao, Philippines.
14 May 1944:
At 0250, departs Polloc and arrives at Glan, Mindanao, Philippines later that day.
15 May 1944:
Departs Glan and at 1723, arrives at Davao. W-22 is detached.
18 May 1944:
Departs Davao and arrives at Malalag, Mindanao, Philippines later that day.
1 June 1944:
Departs Malalag.
3 June 1944:
Arrives at Rangas, West Celebes (now Sulawesi), NEI.
4 June 1944:
Departs Rangas.
5 June 1944:
Arrives at Tarakan, Borneo, NEI.
11 June 1944:
Departs Tarakan.
12 June 1944:
Arrives at Karang Besar, Borneo.
13 June 1944:
Departs Karang Besar.
14 June 1944:
Arrives at Kutei (Mahakam) estuary, Borneo.
17 June 1944:
Departs Kutei and arrives at Samarinda, Borneo later that day.
18 June 1944:
Departs Samarinda and arrives at Loakoeloe, Mahakam River between Samarinda and Tenggarong, later that day.
19 June 1944:
Departs Loakoeloe and arrives at Samarinda. Departs there and arrives at Toengkoe Kajoe, Mahakam estuary later that same day.
20 June 1944:
Departs Toengkoe Kajoe and arrives at Nubi, Mahakam estuary later in the day.
21 June 1944:
Departs Nubi and arrives at Kutei later that day.
22 June 1944:
Arrives at Balikpapan, Borneo.
29 June 1944:
Departs Balikpapan in a convoy with auxiliary gunboat TAIKO MARU, IJN transport SUITEN MARU and civilian cargo ship (C-AK) TAKASAN MARU. Soon after departure, due to severe hull leaks, SUITEN MARU is beached outside Balikpapan Port for provisional repairs.
30 June 1944:
Arrives at Kota Baru, Laut, Borneo.
4 July 1944:
At 0800, departs Kota Baru. Joins a convoy consisting of TAIKO and TAKASAN MARUs escorted by minelayer WAKATAKA.
5 July 1944:
At 1858, arrives at Doangdoangan Besar, Macassar Strait, NEI.
6 July 1944:
At 0558, departs Doangdoangan Besar.
7 July 1944:
At 2100, arrives at Macassar, Celebes (now Sulawesi).
10 July 1944:
Departs Macassar.
11 July 1944:
Arrives at Malasoro, Celebes.
12 July 1944:
Departs Malasoro and arrives at Benteng, Salajar, NEI later that day.
13 July 1944:
Departs Benteng and arrives at Randjuni Besar, Matjan Islands, NEI later that same day.
14 July 1944:
Departs Randjuni Besar and arrives at Kabaena, NEI later in the day.
15 July 1944:
Departs Kabaena and arrives at Pora Pora anchorage (now Teluk Labungka), west coast of Boeton Island, NEI later that day.
16 July 1944:
Departs Pora Pora and arrives at Telok Dalam, Celebes later that same day.
17 July 1944:
Departs Telok Dalam and arrives at Salabanka, Kaleroang Islet, NEI later in the day.
18 July 1944:
Departs Salabanka and arrives at Poelau Bangkoeloe, NEI later that day.
19 July 1944:
Departs Poelau Bangkoeloe and arrives at Samada Kechil Islet off the NW coast of Taliboe Island, NEI later that same day.
20 July 1944:
Departs Samada Kechil Islet.
22 July 1944:
Arrives at Ambon, Moluccas, NEI.
7 August 1944:
At 1300, departs Ambon in a convoy consisting of auxiliary cargo ship KEMBU (TATEBE) MARU (4,519 GRT), TAIAN and KINREI MARUs escorted by minelayer WAKATAKA, subchasers CH-26 and CH-60 and auxiliary subchaser CHa-116.
9 Augst 1944:
At 1330, the convoy arrives at Bitung, Celebes. Later the convoy departs and at 1600, arrives at Staring Bay, Celebes.
25 August 1944:
Arrives at Macassar.
23 September 1944:
At 1700 departs Makassar with minesweeper W-5, auxiliary netlayer NAGARA MARU auxiliary submarine chasers CHa-113 and SHONAN MARU No. 2 and auxiliary minesweeper KEINAN MARU in a convoy also consisting of IJA transports KURAMASAN, KANTO and TATSUYASU MARUs, and auxiliary oiler KINREI MARU.
4 September 1944:
At 0200 off Laut Strait, Borneo, Netherlands East Indies (now Kalimantan, Indonesia) the auxiliary oilers KINREI MARU and UNKAI MARU No. 12 detach and head to Balikpapan.
6 September 1944:
Arrives at Balikpapan.
10 September 1944:
Departs Balikpapan.
12 September 1944:
Arrives at Samarinda.
14 September 1944:
Departs Samarinda and arrives at Loakoeloe later that day.
15 September 1944:
Departs Loakoeloe.
16 September 1944:
Arrives at Balikpapan.
5 October 1944:
Departs Balikpapan.
11 October 1944:
Arrives at Tarakan.
25 October 1944:
At 0650, departs Tarakan in convoy M-246 also consisting of CAROLINE MARU and oilers TAKASAGO MARU No. 2, NANSHIN MARU No. 8, NANKO MARU No. 1 and HORAI MARU No. 7 escorted by patrol boat PB-2 and subchasers CH-5 and CH-31. At 0945, at 04.16N-118.05E UNKAI MARU No. 12 runs aground on a reef. At 1437, the convoy stops and emergency anchors.
26 October 1944:
At 0700, convoy M-246 departs. PB-2 is detached to assist UNKAI MARU NO. 12.
27 October 1944:
At 0500, frees itself from the reef. Thereafter anchors. Departs later that evening escorted by PB-2. At 2310, both vessels are attacked by 1 B-24.
29 October 1944:
At 1030, arrives at Honda Bay, N of Puerto Princesa, Palawan, Philippines. Later that day, with PB-2, rejoins convoy M-246 at Puerto Princesa.
30 October 1944:
Departs Puerta Princessa. At 1140, convoy M-246 dissolves. At 1323, undergoes an air attack. Fires four rounds.
31 October 1944:
At 2000, arrives at Taytay Bay, NE Palawan, Philippines.
1 November 1944:
Departs Taytay Bay. Later that day, the convoy is attacked by LtCdr George H. Laird's (USNA ’33) USS BLACKFIN (SS-322) and LtCdr William T. Kinsella's (USNA ’34) USS RAY (SS-271). At 0923, Laird torpedoes and sinks UNKAI MARU No. 12 and CAROLINE MARU, both with a full load of fuel oil each, at 12-57N, 120-12E. UNKAI MARU No. 12 sinks 35 miles west of Mindoro, Philippines, with 28 crewmen KIA, while CAROLINE MARU has 13 crewmen KIA. At 1042, Kinsella sinks HORAI MARU No. 7, carrying 1,425-tons of petroleum at the same location. 10 of the crew are killed. Later that day, the rest of former convoy M-246 arrives at Manila.
Author’s notes:
Thanks go to Gengoro S. Toda of Japan and to Erich Muehlthaler of Germany.
- Berend van der Wal, Gilbert Casse and Peter Cundall.
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