SOKAITEI!

(W-7 class minesweeper scanned from SOTW, V. 507)

IJN Minesweeper W-12:
Tabular Record of Movement

© 2005-2013 Bob Hackett and Peter Cundall

Revision 5


28 May 1938:
Tokyo. Laid down at the Ishikawajima shipyard.

18 February 1939:
Launched and numbered W-12.

15 August 1939:
Completed and registered in the IJN at the Sasebo Naval District.

1 June 1941:
W-12 is assigned to Vice Admiral Takahashi Ibo's (36) (former CO of KIRISHIMA) Third Fleet's 1st Base Force in MineSweepDiv 21 with W-7, W-8, W-9, W-10 and W-11.

21 September 1941:
Cdr (Rear Admiral, posthumously) Kitamura Masayuki (45) assumes command of MineSweepDiv 21.

27 November 1941:
Departs Sasebo.

30 November 1941:
Arrives at Mako, Pescadores.

December 1941:
Lt Hanyu Hidekazu assumes command.

7 December 1941: Operation "M" - The Attack on the Southern Philippines:
W-12 departs Mako in Rear Admiral (later Vice Admiral) Nishimura Shoji’s (39) Vigan Invasion Force.

17 December 1941:
Departs Amami O-Shima. Escorts convoys to Lamon Bay and Davao.

9 January 1942: Operation "H" - The Invasion of Celebes, Netherlands East Indies:
MineSweepDiv 21's W-12, W-7, W-8, W-9 and W-11, light cruiser NAGARA, patrol boats PB-1, PB-2, PB-34 and SubChasDiv 1's CH-1, CH-2 and CH-3 depart Davao escorting eight transports carrying Captain (later Vice Admiral) Mori Kunizo's (40)(former CO of AO SATA) Sasebo No. 1 Combined Special Naval Landing Force (SNLF) and Rear Admiral Kubo Kyuji's (38) 1st Base Force.

11 January 1942: The Invasion of Menado, Celebes Dutch East Indies:
Rear Admiral Kubo Kyuji’s (38) 1st Base Force with MineSweepDiv 21, NAGARA, patrol boats and SubChasDiv 1’s CH-1, CH-2 and CH-3 provides escort for the Menado invasion force of eight transports carrying Captain Mori's Sasebo No. 1 Combined SNLF.

At 0300, the SNLF lands on Kema, Celebes. At 0400, they land on Menado. Later, 334 men of Cdr (later Captain) Horiuchi Toyoaki's (50) (later XO of TAKAO) Yokosuka No. 1 SNLF (Air) are dropped successfully from Mitsubishi G3M1-L Nell converted transport aircraft in the Menado-Kema area. The paratroops seize Langoan airfield.

21 January 1942:
Escorts the Kendari invasion convoy and conducts minesweeping.

23-24 January 1942: The Invasion of Kendari, Celebes:
MineSweepDiv 21’s W-12, W-7, W-8, W-9 and W-11, DesRon 10’s light cruiser NAGARA, DesDiv 15’s HAYASHIO, KUROSHIO, OYASHIO and NATSUSHIO, DesDiv 16’s TOKITSUKAZE, HATSUKAZE, AMATSUKAZE and YUKIKAZE, and Subchaser Div 1’s CH-1 and CH-2 escort Rear Admiral Kubo’s Kendari Invasion Force under consisting of six troop transports carrying Captain (later Vice Admiral) Mori Kunizo’s Sasebo Combined Special Naval Landing Force (SNLF). The 11th Seaplane Tender Division’s CHITOSE and MIZUHO provide distant support.

29 January 1942:
Departs Kendari. Escorts the Ambon, invasion convoy.

31 January 1942: The Invasion of Ambon Island, Moluccas, Netherlands East Indies:
The convoy includes ten transports carrying 820 men of Rear Admiral (later Vice Admiral) Hatakeyama Koichiro's (39) (former CO of KINUGASA) Kure No. 1 SNLF, elements of the Sasebo SNLF and the 228th Infantry Regiment escorted by Rear Admiral (later Vice Admiral) Tanaka Raizo's (41) DesRon 2’s light cruiser JINTSU, DesDiv 8’s ASASHIO, MICHISHIO, ARASHIO and OSHIO, DesDiv 15’s HAYASHIO, KUROSHIO, OYASHIO and NATSUSHIO, DesDiv 16’s TOKITSUKAZE, HATSUKAZE, AMATSUKAZE and YUKIKAZE, Minesweeper Div 21’s W-7, W-8, W-9, W-11 and W-12 and Subchaser Div 1’s CH-1, CH-2 and CH-3. CHITOSE and MIZUHO arrive at Ceram and provide air cover for the invasion convoy.

2 February 1942:
Ambon. Lt Hanyu's W-12 explodes a mine while sweeping and is damaged.

10 March 1942:
Assigned to the 2nd Southern Expeditionary Fleet’s 21st Special Base Force.

20 April 1942:
At 0700 departs Ambon with W-11. Escorts convoys.

21 April 1942:
At 1240 W-11 and W-12 arrive at Kendari and depart at 1440.

24 April 1942:
At 1600 W-11 and W-12 arrive at Surabaya, Java. Escorts convoys .

30 April 1942:
At 1515 departs Surabaya.

8 May 1942: Operation "S" – The Seizure of the Lesser Sunda Islands:
At 0900, W-12, CruDiv's 16 light cruiser IZUSU, torpedo boat TOMOZURU and subchasers CH-6, CH-19 and CH-20 depart Surabaya for Lombok Island escorting Rear Admiral (later Vice Admiral) Hara Kenzaburo’s (37) Lesser Sunda Islands Invasion Force consisting of seaplane tender SANYO MARU and minelayer WAKATAKA carrying the Yokosuka No. 1 SNLF and two Army transports.

9 May 1942:
At 1700, the invasion convoy arrives at Mataram, Lombok Island. The SNLF lands and occupies the island.

10 May 1942:
Departs Mataram.

13 May 1942:
At 0830, arrives at Bima, Soembawa Island. The SNLF lands and occupies Bima. At 1000, departs Bima.

14 May 1942:
Arrives at Reo, Flores Island. The SNLF lands and occupies Reo.

16 May 1942:
Arrives at Labuhanbadjo, Flores Island and at Waingapoe, Soemba Island. The SNLF lands and occupies both locations.

17 May 1942:
Arrives at Larantoeka and Endeh, Flores Island. The SNLF lands and occupies both locations.

12 August 1942:
Arrives at Surabaya. Drydocked for hull repairs.

26 August 1942:
Departs Surabaya. Escorts a convoy.

2 September 1942:
Departs Davao.

6 September 1942:
Arrives at Manila.

8 September 1942:
Departs Manila.

10 September 1942:
Arrives at Mako.

12 September 1942:
Departs Mako.

16 September 1942:
Arrives at Sasebo.

22 September 1942:
Drydocked at Sasebo.

24 October 1942:
Undocked.

29 October 1942:
Departs Sasebo.

2 November 1942:
Arrives at Takao and departs later that day.

4 November 1942:
Arrives at Manila.

5 November 1942:
Departs Manila.

9 November 1942:
Arrives at Balikpapan.

12 November 1942:
Departs Balikpapan.

14 November 1942:
Arrives at Surabaya.

16 November 1942:
Surabaya. Sweeps the Kohoku waterway for mines.

19 November 1942:
Arrives back at Surabaya.

21 November 1942:
Departs Surabaya and escorts a convoy.

23 November 1942:
Arrives back at Surabaya. Later that day departs Surabaya and sweeps the approaches for mines.

25 November 1942:
Returns to Surabaya.

26 November 1942:
Again departs Surabaya and sweeps the approaches for mines.

27 November 1942:
Arrives back at Surabaya. Later that day departs Surabaya on an escort mission.

29 November 1942:
Arrives at Kendari.

8 December 1942:
Departs Surabaya. Escorts a convoy to Ambon.

1 January 1943:
Arrives at Batavia.

3 January 1943:
Departs Batavia with KINSEN MARU and an unknown vessel.

8 January 1943:
Early am arrives at Surabaya.

9 January 1943:
Departs Surabaya on an escort mission.

11 January 1943:
In the late evening arrives at Zandhuis Banken (Pulau Sabadur).

13 January 1943:
Departs Zandhuis Banken still on an escort mission.

16 January 1943:
Arrives at Ambon.

18 January 1943:
Early am departs Ambon on an escort mission.

23 January 1943:
Arrives at Surabaya.

3 February 1943:
Departs Surabaya on an escort mission.

6 February 1943:
Arrives back at Surabaya.

12 February 1943:
Departs Surabaya on an escort mission.

16 February 1943:
Arrives at Kupang and departs later the same day.

17 February 1943:
Arrives at Dili.

18 February 1943:
Leaves Dili port and patrols outside.

19 February 1943:
Arrives at Kebon and departs later that day.

20 February 1943:
Arrives at Dili and departs later that day.

21 February 1943:
Arrives off Lautem and undertakes patrols.

24 February 1943:
Arrives at Lautem.

25 February 1943:
Arrives at Kebola Bay (Teluk Kalabahi).

26 February 1943:
Departs Kebola Bay on an escort mission.

2 March 1943:
Arrives at Surabaya.

6 March 1943:
Departs Surabaya on an escort mission.

9 March 1943:
Breaks off escort mission to anchor at undisclosed location.

10 March 1943:
Resumes the escort mission.

11 March 1943:
Arrives at Ambon.

13 March 1943:
Departs Ambon on an escort mission.

15 March 1943:
Arrives at Babo.

16 March 1943:
Departs Babo on an escort mision.

17 March 1943:
Arrives at Kaimana.

19 March 1943:
Departs Kaimana on an escort mission.

20 March 1943:
Temporarily anchors at an undetermined location.

21 March 1943:
Departs on escort mission.

23 March 1943:
Arrives at Ambon.

24 March 1943:
Departs Ambon on an escort mission.

25 March 1943:
Temporarily anchors at an undetermined location.

26 March 1943:
Resumes voyage.

29 March 1943:
Arrives at Surabaya.

1 April 1943:
Departs Surabaya.

4 April 1943:
Arrives Jakarta and departs later on patrol.

7 April 1943:
Arrives at Christmas Island.

9 April 1943:
Departs Christmas Island and resumes patrol.

12 April 1943:
Arrives at Jakarta.

13 April 1943:
Departs Jakarta on patrol.

16 April 1943:
Arrives at Surabaya.

18 April 1943:
Lt Kawano Atsumu assumes command.

25 April 1943:
Departs Surabaya on an escort mission.

30 April 1943:
Arrives at Ambon.

2 June 1943:
Escorts convoys to western New Guinea.

1 July 1943:
At Ambon.

5 July 1943:
At 0000 departs Ambon.

7 July 1943:
Late that evening arrives at Kaimana.

9 July 1943:
Late that evening departs Kaimana on an escort mission.

12 July 1943:
Arrives at Ambon.

14 July 1943:
Departs Ambon.

19 July 1943:
Arrives at Surabaya.

21 July 1943:
Departs Surabaya.

23 July 1943:
Arrives at Macassar.

24 July 1943:
Departs Macassar for Lombok area.

27 July 1943:
Arrives back at Surabaya.

1 August 1943:
Arrives at Surabaya. Drydocked.

13 August 1943:
Undocked.

15 August 1943:
Departs Surabaya. Escorts a convoy to Ambon.

21 August 1943:
At 1530 arrives at Ambon.

25 August 1943:
At 1600 departs Ambon on an escort mission.

27 August 1943:
At 0645 arrives at Kaimana. Later departs and returns to Ambon.

30 August 1943:
At 0730 arrives at Ambon.

3 September 1943:
At 1300 arrives at Maumere.

4 September 1943:
At 1800 departs Maumere on an escort mission.

7 September 1943:
At 1200 arrives at Surabaya.

11 September 1943:
At 1100 departs Surabaya on an escort mission.

14 September 1943:
At 0900 arrives at Jakarta.

15 September 1943:
At 0000 departs Jakarta on an escort mission.

22 September 1943:
At 1500 arrives at Ambon.

25 September 1943:
At 1000 departs Ambon on an escort mission.

26 September 1943:
At 1330 arrives at Bula.

9 October 1943:
At 0828 departs Bula (or some other location in area) on an escort mission.

11 October 1943:
At 1800 arrives at Surabaya.

15 October 1943:
At 1200 departs Surabaya on an escort mission.

17 October 1943:
At 1700 arrives at Jakarta.

20 October 1943:
At 1830 departs Jakarta on an escort mission.

22 October 1943:
At 1430 arrives at Surabaya.

29 October 1943:
At 0955 departs Surabaya on an escort mission.

1 November 1943:
Arrives back at Surabaya.

3 November 1943:
At 1030 departs Surabaya on an escort mission.

5 November 1943:
At 1630 arrives at Batavia.

6 November 1943:
At 0900 departs Batavia on an escort mission.

9 November 1943:
At 0830 arrives at Balikpapan.

10 November 1943:
At 0800 departs Balikpapan escorting SENKO MARU.

E 12 November 1943:
W-12 hands over escort to W-8 at 04-00S, 112-00E and heads for Surabaya. SENKO MARU and W-8 proceed to Padang.

13 November 1943:
At 1930 arrives at Surabaya.

16 November 1943:
At 1600, departs Surabaya escorting NANKAI MARU.

17 November 1943:
W-12 develops engine trouble. The convoy anchors for five hours at Kabanramari Island, Postiljon Archipelago, while W-12 carries out engine repairs.

20 November 1943:
At 0730, arrives at Ambon. W-12 is detached from the convoy that proceeds to Halmahera Island.

26 November 1943:
After 1200, W-12 and W-11 depart Ambon escorting a convoy consisting of SUEZ MARU carrying sick and wounded Japanese troops and 1,102 mostly sick British and Dutch POW's. A E-13A1 "Jake"float plane is located on the fore deck of the ship. The aircraft has a fractured fuselage and is scheduled for repairs at Repair Depot No. 102 in Surabaya.

27 November 1943:
W-11 detaches from the convoy and heads for Kendari.

28 November 1943:
In the evening, W-12 detaches to hunt an enemy submarine, but rejoins SUEZ MARU the following morning.

29 November 1943:
At 0800, LtCdr (later Cdr) Thomas W. Hogan's (USNA ’31) USS BONEFISH (SS-223) fires four torpedoes at the overlapping targets of SUEZ MARU and W-12 at 06-22N, 116-35E. SUEZ MARU's lookouts sight the torpedoes and she avoids two. The third explodes prematurely, but Hogan's fourth torpedo strikes hold No. 4, which along with hold No. 3 contains the POW's. Most of the POW's in the hold are killed in the blast. The ship settles rapidly with a steep list and sinks at 0940.

About 200-250 POW's survive. W-12 rescues about 200-250 Japanese and Koreans, but is unable to accommodate any POW's. After much arguing, and on the insistence of Lt Kawano Atsumu, CO of W-12, IJA Lt Koshio Masaji, in charge of the POW's, agrees to massacre the survivors in the water. Between 1415 and 1630, a rifle party of a dozen men is based on the warship's foredeck and together with a machine gun mounted on the bow opens fire on the POW's. Either in the ensuing massacre, or in the water over the next few days, all but possibly one of the POW's are killed. A solitary survivor, British Soldier Kenneth Thomas, was allegedly rescued 24 hours later by the Australian minesweeper HMAS BALLARAT, although this is unconfirmed.

E 1 December 1943:
W-12 is diverted to Batavia because of mines in Surabaya.

7 December 1943:
Arrives at Surabaya.

3 January 1944:
At 1200 arrives back at Surabaya from an escort mission.

4 January 1944:
At 1200 departs Surabaya on an escort mission.

17 January 1944:
At 1200 arrives back at Surabaya.

22 January 1944:
At 1400 departs Surabaya on an escort mission.

31 January 1944:
At 1700 arrives back at Surabaya.

6 February 1944:
At 0120 departs Surabaya on an escort mission.

9 February 1944:
At 1430 arrives back at Surabaya.

15 February 1944:
At 1400 departs Surabaya on an escort mission.

28 February 1944:
Arrives back at Surabaya.

1 March 1944:
At 1200, W-12 and auxiliary subchaser CHa-103 depart Surabaya escorting a convoy consisting of KITA MARU and tankers KYOEI MARU and TSURUMI.

2 March 1944:
A radio message is received advising Balikpapan Port has been mined. The convoys sails to Pagatan arriving there later that day.

3 March 1944:
At 0400, departs Pagatan. At 0930, KITA MARU is detached from the convoy. Later that day, the convoy arrives in the Kotabaru Sea and anchors there.

4 March 1944:
At 1530, departs Kotabaru Sea and at 2000 arrives at Pamukan Bay.

5 March 1944:
At 0500, departs Pamukan Bay and later that day arrives at Balikpapan.

6 March 1944:
At 1430 W-12 (that must have detached at some point) arrives back at Surabaya.

8 March 1944:
At 1500 departs Surabaya on an escort mission and anti submarine sweep.

16 March 1944:
At 1100 arrives back at Surabaya. At 1710 departs Surabaya on an escort mission.

22 March 1944:
At 1630 arrives back at Surabaya.

26 March 1944:
At 0800, W-12 and subchaser CH-2 depart Surabaya escorting a convoy consisting of NICHINAN, HEIAN and KUNIYAMA MARUs. That evening, anchors at Kangean Island. NICHINAN MARU carries the main body of the IJA 147th Infantry Regiment [less 3rd Battalion].

27 March 1944:
At 0600, departs Kangean Island. At 1000, LtCdr Willard R. Laughon's (USNA ’33) USS RASHER (SS-269) torpedoes and sinks NICHINAN MARU at 07-27S 115-52E. 311 passengers, including the 147th Infantry Regimental Commander and 264 men below the rank of colonel, 28 crewmen and 10 shipboard gunners die. W-12 and subchaser CH-2 counter-attack dropping 35 depth-charges without effect. The convoy returns to Surabaya. At 1825, the convoy again departs port.

28 March 1944:
The escort is handed over to patrol boat No. 104 at 07-15S, 115.50E. W-12 and subchaser CH-2 return to Surabaya.

1 April 1944:
At 1400 arrives at Surabaya. Soon after departs on an escort mission.

7 April 1944:
At 1500 arrives at Surabaya.

12 April 1944:
At 1300, W-12 and subchaser CH-2 depart Surabaya escorting a convoy consisting of MIKASA MARU and SHINSEI MARU No. 17.

15 April 1944:
Arrives at Bima Bay, Sumbawa Island.

16 April 1944:
At 0500 departs Bima Bay.

17 April 1944:
At 1100, arrives at Maumere, Flores Island.

18 April 1944:
At 1300, departs Maumere.

19 April 1944:
At 1930, arrives at Bima Bay.

22 April 1944:
At 0130, departs Bima Bay.

23 April 1944:
At 1200, arrives at Surabaya.

24 April 1944:
At 1800 departs Surabaya on patrol.

25 April 1944:
At 0800 arrives back at Surabaya.

26 April 1944:
At 1200, departs Surabaya escorting CHOYO (ex RNN surveying vessel TYDEMAN) towing 473 ton oil barge (presumed) JOKAI MARU and accompanied by TOYO MARU No. 5 towing 486 ton oil barge (presumed) JODOU MARU.

27 April 1944:
At 1800, arrives at Jakarta.

28 April 1944:
At 1500, departs Jakarta.

30 April 1944:
At 0450 arrives at unidentified location Ke-Ra-Ke-Ya-Tsu-Pu (Krakapu?)

2 May 1944:
At 0930, departs the unidentified location with TYDEMAN towing TOYO MARU No. 5.

5 May 1944:
At 0940, arrives at Jakarta. At 1400 departs port.

7 May 1944:
At 1530 arrives at Surabaya. Drydocked.

25 May 1944:
Undocked.

3 June 1944:
At 0900, W-12 departs Surabaya escorting a convoy to Balikpapan, Borneo consisting of KITA, ENOSHIMA and JAMBI MARUs.

5 June 1944:
Detaches from convoy and at 1055 arrives at Surabaya.

6 June 1944:
At 1000 departs Surabaya escorting TENSHIN MARU.

7 June 1944:
At 1100, is detached and at 1320 arrives at Surabaya.

10 June 1944:
At 1000, W-12 departs Surabaya escorting a convoy consisting of IKUTAGAWA and SEIA MARUs.

11 June 1944:
At 2030, arrives at Laut Island, SE Borneo.

12 June 1944:
At midnight, departs Laut Island. At 1920, arrives at Doangdoangan Island. At 2100, auxiliary subchaser SHONAN MARU No. 1 joins the convoy.

13 June 1944:
At midnight, departs Doangdoangan Island. At 1845, arrives at Tioro Strait.

14 June 1944:
At 0910 departs Tioro Straits and SHONAN MARU No. 1 is detached. At 1800, enters Wowoni Channel.

15 June 1944:
At 0500, departs Wowoni Channel. At 1730, arrives at Litrusaru.

16 June 1944:
At 0900, departs Litrusaru. At 1730 arrives at the N side of Sanana Island.

17 June 1944:
At 0230 departs Sanana Is. At 1630, arrives at Namlea, Buru Island.

18 June 1944:
At 0600, departs Namlea and at 1340, arrives at Ambon.

24 June 1944:
At 0700, W-12, torpedo boat KIJI, auxiliary minesweeper Wa-9 and auxiliary NITTO MARU No. 18 depart Ambon escorting a convoy consisting of SHINNO and KOHOKU MARUs and TENKAI No. 4. At 1720, arrives at Namrole, Buru Island.

25 June 1944:
At 0530, departs Namrole. W-12 and TENKAI No. 4 are detached and head for Surabaya.

27 June 1944:
At 1300, arrives at Ambon.

30 June 1944:
At 1100, W-12, torpedo boat KARI and auxiliary minelayer SHONAN MARU No. 2 depart Ambon escorting a convoy to Surabaya consisting of IKUTAGAWA and SEIA MARUs and LSTs 101 and 102.

1 July 1944:
At 0500 departs Namlea. At 1900 arrives at Vesuvia.

2 July 1944:
At 0700 departs Vesuvia. At 1800 arrives at Great Saloe anchorage.

3 July 1944:
At 0220 departs Great Saloe Anchorage. At 1100 arrives at Laoe Bay.

4 July 1944:
At 0600 departs Laoe Bay. At 1000, arrives off Tandjung Patjube.

5 July 1944:
At 1900, departs Tandjung Patjube.

6 July 1944:
At 2100, arrives at Doangdoangan.

7 July 1944:
At 0650, departs Doangdoangan. W-12 drops depth charges on a suspected submarine without results.

8 July 1944:
At 1130, arrives at Surabaya.

19 July 1944:
At 1600 departs Surabaya on patrol.

20 July 1944:
At 1805 arrives back at Surabaya.

24 July 1944:
At 1015, departs Surabaya escorting SEIA MARU to Ambon.

25 July 1944:
At 2130, arrives at Laut Island and departs there at 2359.

26 July 1944:
At 2000, arrives at Doangdoangan.

27 July 1944:
At 0000, departs Doangdoangan. At 1830, arrives at the west mouth of Tioro Straits and anchors there.

28 July 1944:
At 0530, departs the west mouth of Tioro Straits. At 1800, arrives at Wowoni.

29 July 1944:
At 0400, departs Wowoni. At 1800, arrives at Great Saloe.

30 July 1944: At 0830, departs Great Saloe and at 1340 arrives off Little Saloe.

31 July 1944:
At 0800 departs Little Saloe. At 1830, arrives at Taboro Bay on Tabulu Island.

2 August 1944:
At 0730 arrives at Ambon.

4 August 1944:
At 1330, W-12 and subchasers CH-26, CH-34 and CH-35 depart Ambon escorting a convoy to Staring Bay, Celebes consisting of SHINTAI, KANTO and KURAMASAN MARUs.

5 August 1944:
CH-26 reverses course back to Ambon.

6 August 1944:
At 1400, the convoy arrives at Staring Bay.

8 August 1944:
At 1915 arrives at Surabaya.

13 August 1944:
At 1000, W 12 enters Surabaya Dockyard's No.2 Dock for engine repairs.

17 August 1944:
At 0930, undocked.

19 August 1944:
At 0930, departs Surabaya on trials. Returns at 1520.

23 August 1944:
At 1150, departs Surabaya with KOTSUSEN (Shuttleboat) No. 113 for Christmas Island.

26 August 1944:
At 0900, arrives Christmas Island. Later departs port.

29 August 1944:
At 1130, arrives at Jakarta.

30 August 1944:
At 1730, departs Jakarta escorting SHIRETOKO MARU.

6 September 1944:
After detaching arrives back at Jakarta at 1600.

7 September 1944:
At 1900, departs Jakarta escorting KOTSUSEN No. 113.

11 September 1944:
At 1620, arrives at Christmas Island.

13 September 1944:
At 0820, departs Christmas Island.

15 September 1944:
Ät 1900, arrives at Jakarta.

18 September 1944:
At 1800, departs Jakarta escorting MANYO MARU.

24 September 1944:
At 1930, arrives at Geisse anchorage.

25 September 1944:
At 0710, arrives at nearby Surabaya.

11 October 1944:
At 1330, departs Surabaya.

14 October 1944:
At 0945, NW of Tandjung Selatan meets up with TENCHO MARU. The two ships anchor in Laut Strait at 2245.

15 October 1944:
At 0620, departs Laut Strait and meets up with DAI and KANTO MARUs.

16 October 1944:
At 0250, arrives Bandjermasin. At 0650, departs port and anchors nearby.

17 October 1944:
At 0650, W-12 departs Bandjarmasin, S Borneo, escorting a convoy consisting of KANTO, TENCHO and DAI MARUs. At 1320, a report of an enemy submarine ahead is received and the convoy turns back to Batakani, near Cape Selatan arriving there at 1930.

18 October 1944:
At 2100, departs Batakani.

20 October 1944:
At 1530, arrives at Surabaya.

24 October 1944:
At 1100, docked in Dock No. 2 for repairs.

26 October 1944:
At 1000, undocked.

6 November 1944:
At 1630 departs Surabaya on an anti submarine patrol.

9 November 1944:
At 1110 arrives back at Surabaya.

10 November 1944:
At 1210 departs Surabaya on an escort mission.

16 November 1944:
At 0830, W-12, auxiliary subchasers CHa-2 and CHa-3 depart Sebuku Island, SE Borneo escorting a convoy consisting of AKITSU MARU towing HOKKAI MARU assisted by BAKUKO MARU and cargo ship SHUNSEN MARU.

18 November 1944:
At 2345, arrives in the swept eastern channel to Surabaya Port.

19 November 1944:
At 1230, arrives at Surabaya. HOKKAI MARU enters drydock.

23 November 1944:
At 1530 departs Surabaya on an escort mission.

28 November 1944:
At 1845 arrives at Surabaya.

December 1944:
Transfers to Tarakan area.

1 December 1944:
On that day, FRUMEL provides the following information:
"Vessels for transporting troops between Jolo and Tarakan (Minesweepers 12 and 8 and Subchaser 4), will leave Balikpapan at 1830 on 3rd and arrive Jolo at 1700 on 5th. 880 men of NADA Force comprise the troops to be transported."

5 December 1944:
At 1830 departs Balikpapan on the transport mission with CH-4 and W-8.

7 December 1944:
At 1730 arrives at Jolo.

9 December 1944:
At 0700 arrives at Tarakan.

10 December 1944:
At 1800 arrives back at Balikpapan.

14 February 1945:
At 0600, W-12 and patrol boat No. 10 depart Bandjarmasin escorting convoy BASU-12 consisting of DAI, OTOME, KOMPIRA, NITTEI, HEIYO, TOKUYAMA and NANSHO MARUs, communications boats No's 312, 401, 402, 408 and 409. At 1300, No. 408 breaks down and No. 409 takes the boat in tow back to Bandjarmasin.

15 February 1945:
At 2020, the convoy anchors in Surabaya's eastern channel.

16 February 1945:
At 0800, departs and at 1100, arrives at Surabaya Port.

25 February 1945:
At 1500 departs Surabaya.

8 March 1945:
At 0940 departs Surabaya on a transport mission and joins W-11, W-34 and torpedo boat KARI.

13 March 1945:
At 1730 W-11, W-12, W-34 and KARI arrive back at Surabaya.

15 March 1945:
At 1600 W-12 departs Surabaya on an escort mission.

19 March 1945:
At 1310 arrives back at Surabaya.

24 March 1945:
At 1200 W-12 departs Surabaya and joins W-11 and W-34 on an anti submarine sweep and then an escort mission.

31 March 1945:
At 1500 arrives at Surabaya.

2 April 1945:
At 1000, W-12 and W-34 depart Surabaya for Timor Island, then Sumbawa Island via Bima.

4 April 1945:
W-12 and W-34 and torpedo boat KARI depart Surabaya escorting light cruiser ISUZU transporting an army detachment from Kupang to Sumbawa Island. The ISUZU group is sighted off Paternoster Island by a wolf pack led by Cdr (later Rear Admiral) Francis D. Boyle's (USNA ’34) USS CHARR (SS-328) with LtCdr Herman E. Miller's (USNA ’38) USS BESUGO (SS-32l) and LtCdr William B. Parham's (USNA ’36) USS GABILAN (SS-252), but Japanese aircraft force the pack to dive and they are unable to attack.

5 April 1945:
At 1930, arrives at Kupang, Timor. At 2200, departs Kupang.

6 April 1945:
Boyle's wolf pack is alerted about the position of the Japanese ships by an "Ultra" signals-intelligence message from ComSubPac at Pearl and takes up position near Bima Bay. They are joined there by ComSubSoWestPac's British submarine HMS SPARK.

Kupang Harbor. At dawn, ISUZU embarks an army detachment and departs for Sumbawa. N of Sumbawa, ISUZU is attacked by ten B-25 "Mitchell" bombers of the Dutch 18th Squadron based at Batchelor airfield S of Darwin, Australia. ISUZU is slightly damaged by near-misses. Later, she lands troops at Bima Bay, on the NE coast of Sumbawa.

Near Flores Island, Netherlands East Indies. ISUZU is hit in the bow by bombs from Consolidated B-24J "Liberator" bombers of the RAAF's No. 21 and No. 24 Squadrons based in Northern Australia. Two B-24's are shot down by Japanese aircraft.

Sape Strait, between Sumbawa and Komodo islands. About 1600, Miller's BESUGO fires nine torpedoes at the ISUZU group. They miss ISUZU, but two hit W-12 that has a deckload of troops. W-12 is beached, but torpedoed again and sinks at 08-13S, 119-14E.

At 1508, USN codebreakers intercept and decrypt a message from the CO of the Forward Transportation Unit that reads: “At 1508 W-12 received a torpedo hit forward of the bridge. While backing down it ran aground in the vicinity of the southern tip of the west coast of Komodo Island. We made requisition to the resident Army and Navy Officials at Bima for using the remaining small boats in salvage operations and in landing the soldiers.” (Komodo Island is at 08-40S, 119-25 E.)

14 April 1945:
At 1714, codebreakers intercept a message that reads: “Report of the state of salvage of W-12. At 1508 on 6th April she received a hit from a torpedo in a position approximately 4000 meters to the northwest of Klapa Island. It severed the forward part from the bridge and started a fire from the vicinity of ---- which set light to the fuel. There was no way of ----- the ship and after the work of rescuing the crew out of the after deck and completing the releasing of the material which would float. Complement left the hull. At 16----- she was again torpedoed amidships on the port side and the hull sank. -----.”

25 May 1945:
Removed from the Navy List.


Authors Note:
Thanks go to Mr. Aki of Japan and Matthew Jones of Ohio for help in identifying COs. Thanks to Mr. Gilbert Casse of France for general assistance. Thanks also go to John Whitman of the USA for info on CNO intercepts of Japanese messages. Photo credit goes to Ships of the World (SOTW) via J. Ed Low.

-Bob Hackett and Peter Cundall.


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