W-21 (W-19 class) scanned from Gakken, V. 45

IJN Minesweeper W-20:
Tabular Record of Movement

© 2005-2016 Bob Hackett and Peter Cundall

Revision 15

19 March 1941:
Tokyo. Laid down at Ishikawajima Shipbuilding.

17 September 1941:
Launched and numbered W-20.

10 December 1941:
Reserve Lt Kita Yasaburo is appointed appointed Chief Equipping Officer.

15 December 1941:
Completed and commissioned in the IJN. Reserve Lt Kita Yasaburo is the Commanding Officer.

26 December 1941:
Davao, Philippines. W-20 collides with destroyer MURASAME and is damaged. Thereafter, undergoes repairs.

31 March 1942:
W-20 is coaled by auxiliary gunboat NIKKAI MARU.

30 April 1942:
Rabaul. Between 0515-0730, W-20 is watered by auxiliary ammunition ship KOTOKU MARU.

3 May 1942:
Rabaul. Between 1300-1600, W-20 is coaled by auxiliary ammunition ship KOTOKU MARU.

4 May 1942: Operation “MO” – The Invasions of Tulagi and Port Moresby:
Rabaul, New Britain. W-20 is assigned to Rear Admiral Kajioka's Port Moresby Attack Force with DesRon 6's YUBARI, DesDiv 29’s ASANAGI, OITE, DesDiv 30’s MUTSUKI, MOCHIZUKI and YAYOI and a patrol boat escorting Rear Admiral (later Vice Admiral) Abe Koso's (former CO of HIEI) Transport Force of five Navy and six Army transports, repair ship OSHIMA, oilers GOYO MARU, HOYO MARU, IRO, minesweepers HAGOROMO MARU, NOSHIRO MARU No. 2, FUMI MARU No. 2 and minelayer TSUGARU towards the Jomard Pass in the Louisiade Archipelago. The Port Moresby invasion troops are in this group.

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

Rabaul. Between 0830-0920, W-20 is coaled by auxiliary ammunition ship KOTOKU MARU.

12 May 1942:
At 1200 departs Rabaul on patrol.

13 May 1942:
Arrives back at Rabaul.

14 May 1942:
Rabaul. Between 0500-0930 W-20 is coaled by auxiliary ammunition ship KOTOKU MARU.

15 May 1942:
At 0800 departs Rabaul on an escort mission.

19 May 1942:
At 1500 arrives at Rabaul.

22 May 1942:
At 1700, W-20 departs Rabaul for Moji escorting a convoy consisting of CHOWA, AKIBASAN and SHOKA MARUs.

23 May 1942:
At 0600, an unidentified auxiliary gunboat joins and accompanies the convoy until 2200. W-20 detaches and returns to Rabaul later that day.

24 May 1942:
At 1440 departs Rabaul on an escort mission.

30 May 1942:
At 0940 arrives back at Rabaul.

4 June 1942:
Departs Rabaul on an escort mission.

9 June 1942:
At 0545 arrives back at Rabaul.

16 June 1942:
At 0640 departs Rabaul and patrols [Blanche] Bay entrance, returning later that day.

17 June 1942:
At 1025 departs Rabaul on an escort mission with auxiliary gunboat KEIJO MARU.

21 June 1942:
SW Gavutu Is. At 1415, LtCdr John R. Moore’s old S-44 torpedoes and sinks auxiliary gunboat KEIJO MARU. That same day, W-20 rescues 62 of her survivors, another 63 are KIA.

25 June 1942:
At 1635 arrives back at Rabaul.

30 June 1942:
At 0405 departs Rabaul on an escort mission.

4 July 1942:
Arrives back at Rabaul.

6 July 1942:
Departs Rabaul on an escort mission possibly of NOJIMA MARU from Lae.

9 July 1942:
At 0910 arrives back at Rabaul.

11 July 1942:
At 1450 departs Rabaul on an escort mission.

14 July 1942:
At 0540 arrives back at Rabaul. At 1120 departs Rabaul again on an escort mission. W-20 and W-21 are reassigned to Rear Admiral (later Vice Admiral) Kanazawa Masao's (39)(former CO of KIRISHIMA) 8th Base Force in Vice Admiral Mikawa Gunichi's newly established Eighth Fleet.

15 July 1942:
At 1900 arrives back at Rabaul.

21 July 1942:
Departs on escort mission to Lae.

27 July 1942:
At 0630 returns to Rabaul.

1 August 1942:
At 1140 departs Rabaul on patrol.

2 August 1942:
At 1140 returns to Rabaul.

5 August 1942:
At 1700 departs Rabaul on an escort mission.

6 August 1942:
Arrives at Kavieng and departs later that day.

7 August 19422:
At 1740 arrives back at Rabaul.

8 August 1942:
At 2200 departs Rabaul on patrol.

9 August 1942:
At 1730 arrives back at Rabaul.

10 August 1942:
At 0850 departs Rabaul on an escort mision.

13 August 1942:
At 1030 arrives back at Rabaul.

17 August 1942:
At 0135 W-20 departs Rabaul for Basabua, New Guinea with light cruiser TENRYU and subchasers CH-22, CH-23 and CH-24 escorting a convoy consisting of KAZUURA, RYOYU and KANYO MARUs transporting Rear Admiral (later Vice Admiral) Yamada Sadayoshi's (42)(former CO of KAGA) 25th Air Flotilla's base supplies.

18 August 1942:
At 1730, arrives at Basabua (Basuba).

20 August 1942:
At 1105 arrives back at Rabaul.

24 August 1942:
At 0830 departs Rabaul for Buna.

27 August 1942:
At 0520 arrives back at Rabaul.

30 August 1942:
At 1430 departs Rabaul on an escort mission.

3 October 1942:
At 0640 arrives at Rabaul from escort mission.

4 October 1942:
At 2050 departs Rabaul on escort mission and anti submarine sweep.

10 October 1942:
At 1700 arrives back at Rabaul.

15 October 1942:
At 1400 departs Rabaul on an escort mission.

17 October 1942:
At 2300 arrives back at Rabaul.

20 October 1943:
At 1800 W-20 and W-21 departs Rabaul for Shortland on escort mission and then W-20 only undertakes patrols in Shortland area.

5 November 1942:
At 1600 arrives back at Rabaul.

7 November 1942:
At 1905 departs Rabaul. Meets up with convoy consisting of KENYO and CHIHAYA MARUs inbound from Truk.

10 November 1942:
At 0720 arrives back at Rabaul.

15 November 1942:
At 1600 departs Rabaul on an escort mission.

23 November 1942:
At 2320 arrives back at Rabaul.

25 November 1942:
At 0600 departs Rabaul on an escort mission.

30 November 1942:
At 0700 arrives back at Rabaul.

1 December 1942:
At 1600 departs Rabaul on an escort mission.

3 December 1942:
At 0845 arrives back at Rabaul.

7 December 1942:
At 1705 departs Rabaul on an escort mission.

12 December 1942:
At 1150 arrives back at Rabaul.

16 December 1942:
At 1700 departs Rabaul on an escort mission.

20 December 1942:
At 0930 arrives at Rabaul.

23 December 1942:
At 0530 departs Rabaul on an escort mission.

28 December 1942:
At 1600 arrives back at Rabaul.

31 December 1942:
At 0400 departs Rabaul to assist/rescue survivors of HITERU MARU (wrongly shown in Japanese records under old name RYUFUKU MARU, possibly because callsign records were not up to date).

4 January 1943:
At 1800 arrives back at Rabaul.

8 January 1943:
At 1655 departs Rabaul on an escort mission.

13 January 1943:
At 0815 arrives back at Rabaul.

15 January 1943:
At 1500 departs Rabaul escorting OYO MARU to Solomon Islands. At some point destroyer KAWAKAZE joins escort.

23 January 1943:
At 0655 arrives back at Rabaul. Later that day at 1330 departs on an escort mission.

28 January 1943:
At 1055 arrives back at Rabaul.

31 January 1943:
At 1600 departs Rabaul on an escort mission.

4 February 1943:
W-20 meets unescorted convoy "H" at 00-50S, 150-00E consisting of HAKUSAN and MYOKO MARUs that left Palau the previous day.

5 February 1943:
The convoy arrives safely at Manokwari, New Guinea. At an unknown date W-20 arrives back at Rabaul.

10 February 1943:
At 1930 departs Rabaul on an anti submarine sweep.

11 February 1943:
Arrives back at Rabaul.

18 February 1943:
At 2030 departs Rabaul with submarine chaser CH-16 to assist the aircraft transport KEIYO MARU that has been damaged by LtCdr John R Craig's USS GRAMPUS (SS-207) at 04-55S 152-26E.

19 February 1943:
At 0210 returns to Rabaul.

21 February 1943:
At 0600 departs Rabaul on an escort mission.

26 February 1943:
At 1300 arrives back at Rabaul.

1 March 1943:
W-20 departs on a short escort mission.

2 March 1943:
At 0600 arrives back at Rabaul.

4 March 1943:
At 1200 departs Rabaul on an escort mission.

9 March 1943:
At 0825 arrives back at Rabaul.

11 March 1943:
At 1045 departs Rabaul on an escort mission possibly of MANKO MARU to Kavieng.

13 March 1943:
While escorting NOSHIRO MARU (that had departed Rabaul the previous day) the auxiliary transport is torpedoed by LtCdr (later Rear Admiral) Edward C. Stephan's USS GRAYBACK (SS-208) at 00-10S,151-06E. Stephan claims two hits of four torpedoes he fires in a submerged attack. The damage is light indicating USS GRAYBACK's Mark-14 steam torpedoes may have been duds.

15 March 1943:
At 0800 arrives back at Rabaul possibly escorting TOYO MARU from Mowe anchorage near Kavieng.

17 March 1943:
At 1115 departs Rabaul on an escort mission.

20 March 1943:
At 1500 arrives back at Rabaul likely escorting a convoy with submarine chaser CH-16 from Palau consisting of MIYAURA, HAKUSAN (2197 grt), TATEISHI, ROKKOSAN, ADEN, MILAN, SORACHI, KENKOKU and KANJO MARUs.

26 March 1943:
At 1500 departs Rabaul on an escort mission.

31 March 1943:
At 0725 arrives back at Rabaul.

7 April 1943:
At 1035 departs Rabaul escorting auxiliary seaplane tender KAMIKAWA MARU.

8 April 1943:
At 0600 arrives at the west mouth of Shortland Harbour.

10 April 1943:
At 0525 arrives back at Rabaul.

13 April 1943:
At 1300, W-20 and submarine chaser CH-23 depart Rabaul escorting a convoy consisting of KAIFUKU, TOKO MARUs, YOSHIDA MARU No. 3 and an unidentified merchant ship en route to Palau. Att some point W-20 is detached and returns to Rabaul.

18 April 1943:
At 1130 returns to Rabaul.

20 April 1943:
At 1450 departs Rabaul on way to Takao after transfer to Takao Guard Unit, Taiwan.

30 April 1943:
At around midday returns to Rabaul.

15 May 1943:
Reserve Lt Aizawa Shingo is appointed CO.

2 December 1943:
Arrives at Chinkai.

5 December 1943:
Arrives at Takeshiki, Tsushima and departs later that day.

7 December 1943:
Arrives Sanpo Bay, Korea and departs later that day.

8 December 1943:
Arrives at Takeshiki.

10 December 1943:
Departs Takeshiki.

13 December 1943:
Arrives at Sanpo Bay.

14 December 1943:
Departs Sanpo Bay.

15 December 1943:
Arrives Chinkai and departs later that day on a submarine hunt.

19 December 1943:
Arrives at Chinkai.

20 December 1943:
Bunkers (Refuels).

22 December 1943:
Departs Chinkai on patrol and later that day returns to port.

24 December 1943:
Departs Chinkai and later that day arrives at Fuzan (Pusan), Korea.

30 December 1943:
Departs Fuzan.

31 December 1943:
Arrives at Chinkai.

3 January 1944:
Arrives at Takeshiki.

4 January 1944:
Departs Takeshiki.

5 January 1944:
Arrives at Sanpo Bay.

8 January 1944:
Arrives at Mutsure Jima.

10 January 1944:
Arrives at Chinkai, takes on bunkers, water and supplies and then departs on patrol.

13 January 1944:
Arrives at Chinkai.

14 January 1944:

16 January 1944:
Departs Chinkai.

19 January 1944:
Arrives at Takeshiki.

22 January 1944:
Departs Takeshiki.

25 January 1944:
Arrives at Chinkai.

26 January 1944:
Takes on fresh water.

27 January 1944:

28 January 1944:
Departs Chinkai.

31 January 1944:
Arrives at Takeshiki.

3 February 1944:
Departs Takeshiki.

6 February 1944:
Arrives at Chinkai.

7 February 1944:
Takes on fuel and water.

10 February 1944:
Loads stores.

12 February 1944:
Departs Chinkai and later that day arrives at Takeshiki.

15 February 1944:
Departs Takeshiki on anti submarine patrol.

18 February 1944:
Arrives at Takeshiki.

19 February 1944:
Departs Takeshiki.

24 February 1944:
Arrives at Chinkai.

25 February 1944:

29 February 1944:
Loads stores.

1 March 1944:
Departs Chinkai on patrol.

3 March 1944:
Joins and escorts an Army convoy from Fuzan to Moji.

4 March 1944:
Resumes patrol and later that day arrives at Takeshiki.

5 March 1944:
Departs Takeshiki.

7 March 1944:
Arrives at Yokosuka.

12 March 1944:
W-20 departs from nearby Kisarazu.

13 March 1944:
Ordered to the disaster scene of KOKUYO MARU sunk early that morning by USS SANDLANCE.

19 March 1944:
Arrives at Saipan apparently separately to Higashi- Matsu Convoy No.2.

20 March 1944:
Departs Saipan escorting TAMAHOKO MARU from Higashi-Matsu No.2 Convoy and later that day arrives at Guam.

22 March 1944:
Departs Guam escorting TAMAHOKO MARU.

23 March 1944:
Arrives at Saipan. Bunkers and loads stores.

27 March 1944:
W-20 departs Saipan for Yokosuka escorting a convoy consisting of IKUSHIMA and KEIYO MARUs.

30 March 1944:
USS STINGRAY torpedoes and sinks IKUSHIMA MARU at 20-43N, 143-04E. W-20 rescues survivors.

April 1944:
Lt Tanaka Sanzo assumes command.

4 April 1944:
At 2133, arrives at Yokosuka.

13 April 1944:
At 0630, W-20 departs Yokosuka. At 0730, arrives at Kisarazu.

15 April 1944:
Reserve Lt Tanaka Mitsuzo is appointed Commanding Officer. At 0600, W-20 and W-28 depart Tokyo with destroyers HOKAZE, YUNAGI, UZUKI, kaibokan MIYAKE, minelayers SARUSHIMA, KYOSAI and YURISHIMA and subchasers CD-6, CH-10 and CH-12 escorting convoy "Higashi-Matsu No. 6" consisting of AWAJI, HAKUBA, KATSUKAWA, TAKAOKA, BATAVIA, AWA and HOKUSHIN MARUs bound for Saipan, CHOAN MARU No. 2 and MIKAGE MARU No. 1 bound for Truk, JOKUJA, BISAN and JINSAN MARUs bound for Palau, KAMISHIMA and SHOZAN MARUs bound for Woleai, INARI and TONEGAWA MARUs bound for Guam and TATSUAKI and TAMAHOKO MARUs bound for Chichi-Jima.

23 April 1944:
At 0300, TONEGAWA and INARI MARUs together with W-20 are detached from the convoy and at 1735 arrive at Guam.

25 April 1944:
At 0016, departs Guam a in convoy consisting of TONEGAWA MARU escorted by minelayer SARUSHIMA and W-20. At 1836 arrives at Saipan.

27 April 1944:
At 1140, departs Saipan in convoy HIGASHI MATSU No. 6 (RETURN) consisting of AZUCHISAN, AWAJI, SHOUN, TOAN, SHOZUI, KATSUKAWA, TAKAOKA, TONEGAWA, HOKUSHIN, TATEBE (KEMBU) and AWA MARUs and three unidentified merchant ships escorted by destroyer HOKAZE, minelayer SARUSHIMA, minesweeper W-20, kaibokan MIYAKE, AMAKUSA, CD-6 and CD-10.

4 May 1944:
At 2130, arrives at Yokosuka.

15 May 1944:
At 0900, departs Yokosuka. At 1143 arrives off Tateyama.

17 May 1944:
At 0616, W-20, destroyer HATAKAZE, kaibokan CD-16, MIKURA and MIYAKI, subchaser CH-48, minelayer SARUSHIMA and auxiliary netlayer KOA MARU No. 2 depart Tateyama escorting convoy No. 3515 consisting of HAKUSAN, NIPPONKAI, TOYO, KINSHU, HINKO, REIKAI, EIKO, NATSUKAWA, SEIGA, AKISHIMA, SHOKAI, MEITO and CHIYO MARUs and UNYO MARU No. 8.

23 May 1944:
At about 0900, W-20 is detached from the convoy.

25 May 1944:
At 0708, the convoy arrives safely at Saipan.

28 May 1944:
At 0245, W-20, minelayer SARUSHIMA and auxiliary minesweeper FUMI MARU No. 2 depart Saipan escorting convoy consisting of REIKAI, HINKO MARUs. At 1915, arrives at Guam.

29 May 1944:
At 0400, W-20, minelayer SARUSHIMA and auxiliary minesweeper FUMI MARU No. 2 depart Guam escorting a convoy consisting of NISSHO MARU No. 18 and TAKUNAN and BATAVIA MARUs. At 2030 that day, arrives safely at Saipan.

31 May 1944:
At 0600, W-20, destroyer HATAKAZE, kaibokan CD-12, minelayer SARUSHIMA, auxiliary minesweeper FUMI MARU No. 2 and auxiliary store ship TAKUNAN MARU depart Saipan for Yokosuka escorting convoy No. 4530 consisting of HAKUSAN, JINZAN, EIKO, NATSUKAWA, SHUNSEN, KAIKO and CHIYO MARUs and UNYO MARU No. 8.

2 June 1944:
250 miles W of Uracas Island. At 2207, CHIYO MARU is attacked by LtCdr Edward N. Blakely’s USS SHARK (SS-314) and hit by two torpedoes port side under the rear of the bridge. About ten minutes later, CHIYO MARU sinks at 21-00N 140-30E. W-20 and the other escorts counter-attack and drop a total of thirty-nine depth-charges, but without damage to USS SHARK.

4 June 1944:
317 miles WSW of Iwo-Jima. At 0405, HAKUSAN MARU is attacked by LtCdr John D. Crowley’s USS FLIER (SS-250) and hit port side by two of three torpedoes torpedoes fired. At 0415, HAKUSAN MARU’s stern rises vertically and she sinks at 22-37N 136-50E. W-20 and the other escorts counter-attack and drop thirty-four depth-charges, but without damage to USS FLIER. [1]

8 June 1944:
At 0800, the remainder of the convoy arrives at Yokosuka.

10 June 1944:
At 1615, enters Yokosuka Naval Dockyard.

19 June 1944:
At 0923, departs Yokosuka Naval Dockyard.

24 June 1944:
Departs Tokyo Bay with auxilary submarine chaser CHa-171 escorting convoy No. 3624 consisting of KYUSHU MARU and UNKAI MARU No. 10 for Hachijo Jima.

28 June 1944:
Departs Hachijo Jima escorting a convoy consisting only of UNKAI MARU No. 10 bound for Yokosuka.

29 June 1944:
Arrives at Yokosuka.

2 July 1944:
At 1800, W-20, auxiliary subchaser CHa-9, coast defense vessel YASOJIMA (ex-Chinese light cruiser PING HAI), kaibokan AMAKUSA and OKI, auxiliary minesweeper SHOWA MARU No.7 and an unknown ship depart Yokosuka for Chichi-Jima escorting convoy No. 3702 consisting of SHIBAZONO, EIKO, DAIJI, RYUKO and YAEI MARUs and UNKAI MARU No.7, and Oil Tanker No. 3995.

3 July 1944:
At 1256, arrives at Hachijo Jima. Departs at 1752.

4 July 1944:
After receiving reports of an enemy carrier task force conducting raids on Chichi-Jima, the convoy reverses course for the homeland and later is dissolved.

6 July 1944:
At 0100, departs Yokosuka escorting convoy 3706.

8 July 1944:
At 1128, arrives Mutsure. Departs at 1752.

9 July 1944:
At 0610, arrives at Chinkai.

11 July 1944:
At 0801, departs Chinkai on patrol.

16 July 1944:
At 1457, arrives Moppo (Mokpo), Korea.

19 July 1944:
At 1155, departs Moppo.

22 July 1944:
At 1920, anchors at Sakurajima.

23 July 1944:
At 0555, departs Sakurajima.

25 July 1944:
At 1251, arrives at Chinkai.

28 July 1944:
At 0355, departs Chinkai. At 1602 arrives at Moji.

31 July 1944:
At 1604, departs Moji and at 1704 arrives at Mutsure.

1 August 1944:
At 0400, departs Moji in convoy MO-05 consisting of KAZUURA, TATSUJU, TSUSHIMA, YAMAHAGI, GYOKU, ETAJIMA and HIROTA MARUs escorted by W-20, minelayer SHIRATAKA, destroyer HIBIKI and auxiliary minesweeper Wa-2.

5 August 1944:
Arrives safely at Kinmu Bay, Okinawa.

6 August 1944:
At 0900 departs Kinmu Bay. At 1302, arrives at Nakagusuku Bay..

7 August 1944:
At 0800, departs Nakagusuku Bay. At 1305 arrives at Naha.

9 August 1944:
At 1640, departs Naha having detached from convoy.

11 August 1944:
At 1108, arrives at Moji.

14 August 1944:
At 1534, departs Moji for nearby Mutsure. Arrives there at 1634.

15 August 1944:
At 0600, W-20 destroyer HATSUSHIMO, kaibokan CD-10, CD-20, torpedo-boat HIYODORI and subchaser CH-63 depart Moji for Takao, Formosa escorting convoy MOTA-23 consisting of FUKUREI, EDOGAWA, TAIJO, EIJI, MANSHU, ATSUTA, CHINA, ROZAN, EIMAN, TOYOOKA, KOGYO and AWAJI MARUs and YOSHIDA MARU No. 3, TOYO MARU No. 3 and an unidentified ship. From about noon, the convoy commander believes they are being trailed by enemy submarines.

16 August 1944:
At 1230 an enemy submarine is detected. CD-10 drops depth charges. At 1237 executes an anti submarine sweep with CD-10 and CH-63.

17 August 1944:
Follows the convoy with CD-10 and CH-63 meanwhile continuing anti submarine sweeping. At 2000 they catch up with the convoy and end anti submarine sweeping.

18 August 1944:
At 1950, in an effort to shake off the enemy, the convoy puts into Kagoshima Bay, southern Kyushu.

20 August 1944:
At 0409, the convoy departs Kagoshima for Takao.

24 August 1944:
Off NW Formosa. At about 0700, off the coast of Sancho Point, Formosa (now cape Sandiajiao, Taiwan), as planned four ships detach from the formation bound for Keelung. About the same time, LtCdr Henry S. Monroe's USS RONQUIL (SS-396) attacks YOSHIDA MARU No. 3. She is hit by a number of torpedoes, her bomb and shell magazines erupt and a huge explosion rents the ship. She immediately sinks. At the same time, FUKUREI MARU is also torpedoed. She lists, floods, comes to a stop and then drifts ashore. On 13 November 1944, FUKUREI MARU is officially abandoned there. After the submarine attacks, the convoy changes course.

25 August 1944:
Arrives at Keelung at 1400.

27 August 1944:
At 0900 departs Keelung.

28 August 1944:
The convoy arrives at Saei, Formosa (now Tsoying harbour, Taiwan).

29 August 1944:
The convoy departs Port Saei and it arrives at Takao later that day.

30 August 1944:
At 1900 arrives at Takao.

31 August 1944:
At 1200 W-20 and CH-41, departs Takao escorting tanker RIKKO MARU.

2 September 1944:
At 1141, arrives at Mako, Pescadores. W-20 and W-41 join convoy MI-17 consisting of tankers NITTETSU and SHIMOTSU MARUs, cargo ships BAIKAL, AMAHI, DAITEN, NORWAY, ARAOSAN, NICHIZUI, HOKUREI MARU, SHINYO MARU No. 8 and three unidentified ships escorted by destroyers SHIOKAZE and KURETAKE, kaibokan CD-18, minelayer YURISHIMA and W-17. The convoy anchors at Mako.

4 September 1944:
At 1000, the convoy departs Mako for Manila. At an undetermined point, W-20 detaches from the convoy, probably after the dangerous Luzon Strait leg has been partly negotiated.

5 September 1944:
Meanwhile at 1900, destroyers HATSUHARU, HIBIKI, kaibokan CD-1, CD-3, CD-5, CD-7, subchaser CH-63, torpedo-boat HIYODORI, auxiliary subchaser CHa-67 depart Takao for Manila escorting convoy TAMA-25 consisting of KOGYO, EIJI, MANSHU, EIMAN, ATSUTA, SHOKOKU, NANREI, ROZAN, EIMAN, TOYOOKA and HOKUSEN MARUs. Previously known as MOTA-23, this convoy was enroute to Takao before being diverted to Keelung. The convoy is carrying reinforcements, equipment and ammunition for the defense of the Philippine Islands.

6 September 1944:
At 0230, as TAMA-25 sails south, KOGYO MARU develops engine troubles and turns back. At about 0423, EIJI MARU carrying units of the Kwantung Army's 8th. Infantry Division and 2nd Tank Division, strikes a mine at 22-19N, 120-30E. HIBIKI comes alongside to assist, but also strikes a mine that severely damages her bow. She returns to Takao. At about 0500, EIJI MARU is ordered abandoned. At 0800, there is another explosion and EIJI MARU sinks. The convoy withdraws to nearby Tungchiang, arriving at 1738. EIMAN MARU suffers engine troubles and also returns to Takao.

Meanwhile W-20 and convoy MI-17 arrive at Aparri and depart at 2200.

7 September 1944:
At 2150 convoy TAMA-25 departs Tungchiang. The convoy reforms and adopts a zig zag formation. Meanwhile W-20 is detached from MI-17 on a submarine hunt. The ship does not rejoin the convoy again.

8 September 1944:
At 0200 submarine chaser CH-41 meets up with convoy TAMA-25. At 1100 W-20 meets up with TAMA-25.

9 September 1944:
43 miles NW of Calayan Island. At about 0315, TOYOOKA MARU is torpedoed by LtCdr (later Rear Admiral) Charles E. Loughlin's USS QUEENFISH (SS-393). She sinks five minutes later at 19-45N, 120-55E. 1,036 soldiers and nine crewmen are killed. At 0319, MANSHU MARU is hit by a torpedo from QUEENFISH on her starboard side. She takes on a list, then two more torpedoes strike No. 3 hold and the engine room. The list increases and by 0322 sinks by the stern. She was carrying 1,492 men of the 42nd Infantry Regiment, plus her crew. 900 are killed. At 2120, the convoy seeks temporary shelter at Aparri. At 2250, the convoy departs hugging the coast. After rescuing survivors, W-20 is detached and proceeds ahead to Santa Cruz.

10 September 1944:
At 1714 the convoy arrives at San Fernando.

11 September 1944:
At 0003, W-20 arrives at Santa Cruz. Departs at 0654 for Takao with CH-41.

12 September 1944:
At 1930, convoy TAMA-25 anchors at Santa Cruz. Meanwhile at 1200 W-20 arrives back at Takao.

13 September 1944:
At 0640 the convoy departs Santa Cruz and at 1940, arrives in Subic Bay. It is learned the Americans have been attacking the Visayas in the Central Philippine Islands since 12 September.

14 September 1944:
At 0325, because of the danger of attacks in Manila, the convoy raises anchors and heads back north. At 1500, it arrives back at Santa Cruz. For the next two days the convoy remains on standby. Meanwhile at 1200 W-20 departs Takao to rejoin the convoy.

15 September 1944:
At 0900 apparently meets up with the convoy. At 1200 arrives at Basco and departs at 1820.

16 September 1944:
At 1147 arrives at Takao.

18 September 1944:
At 0630, W-20 and W-17, subchasers CH-20, CH-41 and CH-63 depart Takao for Manila escorting convoy TAMA-26 consisting of MIZUHO, SHIRANESAN, EIMAN, ARABIA, TEMPI, HOTEN, TSINGTAO, AWAJI and NICHINAN (1945 grt) MARUs and TOYO MARU No. 3.

21 September 1944:
At 0300, HOTEN MARU suffered engine troubles and remains behind at Musa. At 0700, a friendly aircraft flies overhead to a position forward of the convoy from which it dive-bombs a submarine. At the same time, three torpedoes are seen approaching. AWAJI MARU, carrying 500 tons of ammunition, 600 passengers and 67 crewmen, is struck in the engine room by two torpedoes fired by LtCdr (later Vice Admiral) Glynn R. Donaho's USS PICUDA (SS-382). AWAJI MARU lists to port, then splits into two parts. Her cargo begins to explode. Abandon Ship is ordered. At 0705, the forward part of the ship rises vertically, then sinks, the rear half quickly follows. NICHINAN MARU remains behind to rescue survivors. At 0745, the convoy manages to get back into formation and head southwards again.

At 0835, MIZUHO MARU is torpedoed by LtCdr Louis D. McGregor's USS REDFISH (SS-395). Hit by three torpedoes, the ship takes on a list and starts to sink by the stem. She is immediately abandoned. Soon after, she sinks at 18-37N, 120-4IE. MIZUHO MARU was carrying 5, 415 persons, 1, 313 of whom die. Also onboard were horses, baggage and equipment plus a large quantity of ammunition. W-17 counterattacks while W-20 rescues 370 survivors and the other vessels pick up more survivors. At 2215, the convoy arrives at Lapoc Bay.

24 September 1944:
At 1030, arrives at Lapoc. Departs at 1858.

26 September 1944:
At 1645, arrives at North San Fernando.

28 September 1944:
At 0147, departs San Fernando. At 1000 arrives at Santa Cruz. Departs at 1715.

29 September 1944:
At 1200 arrives back at North San Fernando.

30 September 1944:
At 0700 departs San Fernando. At 2053, arrives at Santa Cruz.

1 October 1944:
At 0634, departs Santa Cruz still escorting TAMA-26. At 2056, arrives at Manila.

3 October 1944:
W 20 departs Manila at 1555 to Corregidor.

4 October 1944:
Manila. W-20, W-41 and subchaser CH-41 are assigned to escort convoy MATA-28 to Takao, Formosa. The ships anchor in the Cabcaben Sea on the SE side of the Bataan Peninsula. The convoy formation is organized to include KOHOKU, KOKUREI, BUNZAN, SHOEI, HOKUREI, TERUKUNI and HISHIGATA MARUs and SHINYO MARU No. 8. At 0100, the convoy departs arriving the same day at 1908 at Santa Cruz.

5 October 1944:
At 0630, the convoy departs Santa Cruz arriving the same day at 1800 at San Fernando.

6 October 1944:
While at San Fernando, convoy MATA-28 absorbs convoy MIMA-11 consisting of oilers KAMOI and TACHIBANA and OMINE MARUs and YAMAMIZU MARU No. 2. At 0618, the reformed convoy departs San Fernando for Takao escorted by W-20, kaibokan CD-8, CD-32 and CD-25, subchasers CH-28, CH-30, CH-33 and CH-41.

At about 0800, LtCdr Henry C. Stevenson's USS ASPRO (SS-309) attacks the convoy. Stevenson fires three torpedoes by periscope at a tanker and claims one hit, but actually achieves no results. At 1530, LtCdr William C. Thompson's USS CABRILLA (SS-288) torpedoes HOKUREI MARU and YAMAMIZU MARU No. 2. YAMAMIZU MARU No. 2 sinks. HOKUREI MARU is badly damaged and beached off Vigan.

At 1830, the convoy retires to Lapoc Bay, Philippines.

7 October 1944:
At 0030, after receiving a radio message warning of an American task force off the E coast of Formosa, the convoy splits in two with KAMOI, KOHOKU, BUNZAN, TACHIBANA, HOKUSEN, SHOEI and HISHIGATA MARUs heading for Yulin, China. SHINYO MARU No. 8, TERUKUNI and OMINE MARUs and two unidentified escorts remain behind. At about 0600, KAMOI and TACHIBANA MARU split away from the convoy. They are accompanied by CD-8 and a subchaser. This leaves the convoy covered by W-20, CD-32, CD-25 and CH-41.

8 October 1944:
At 1630, the air raid warning for Takao is cancelled. At 1800, the convoy reverses course for Takao. At 2325, KOHOKU MARU is torpedoed and sunk in a night surface radar attack by LtCdr Victor B. McCrae's USS HOE (SS-258). Earlier that night, in a similar attack, McCrae also torpedoes and heavily damages CD-8.

9 October 1944:
At 0142, Cdr Alan B. Banister's USS SAWFISH (SS-276) makes a night surface radar attack on TACHIBANA MARU. Banister fires 10 torpedoes and gets three hits that sink TACHIBANA MARU at 19-33N, 116-38E. CD-8 rescues survivors. KAMOI is detached and proceeds to Hong Kong. At 1600, the rest of convoy MATA-28 is diverted from Takao to Hong Kong.

11 October 1944:
At 1013, convoy MATA-28 arrives at Hong Kong.

27 October 1944:
At 1958, W-20, subchasers CH-30, CH-33 and auxiliary subchaser and CHa-41 depart Hong Kong for Takao escorting convoy HOMA-1 consisting of HAMBURG, YASUKUNI, EIWA, SHINETSU and KANETSU MARUs and NISSHO MARU No. 18.

30 October 1944:
At 1358, convoy HOMA-1 arrives at Takao.

1 November 1944:
At 1712, W-20 departs Takao with destroyer KURETAKE, minesweeper W-17, kaibokan CD- 1, CD-3, CD-7, subchaser CH-41, and fleet storeship KURASAKI escorting convoy MOMA-06 consisting of HAMBURG, KAKOGAWA, DAITOKU, SHIMOTSU, ASOKAWA, SEIWA, SHINETSU, TOTTORI, EIWA, SHINSHO, SEKIHO, ATLAS MARUS, TOYO MARU No. 3.

3 November 1944:
Near Lingayen Gulf, Luzon, Philippines. A temporary wolf pack is formed consisting of consisting of Cdr (later Rear Admiral) Wreford G. Chapple’s BREAM (SS-243), LtCdr William T. Kinsella’s RAY (SS-271), LtCdr Maurice W. Shea’s RATON (SS-270) and LtCdr (later Captain) Enrique D. Haskins’ GUITARRO (SS-363). Meanwhile, the convoy proceeds into the danger zone. While in the Bashi Channel, the convoy evades torpedoes probably fired by LtCdr Robert E. Ward's USS SAILFISH (SS-192). W-20 remains in the area for awhile to keep the submarine down, then shelters with the convoy in Lapoc Bay, N of Vigan, arriving there at 1800. At 2229, arrives at Sabtang Island.

At 0300, USN codebreakers intercept and decrypt a message from No. 1 Maritime Transport Commander to MOMA-06 convoy that reads: “Coast Defense Ship No. 11 will carry out screen of ---- and at the same time will execute anti-submarine sweep. Minesweeper No. 20, KURASAKI and No. 3 TOYO MARU will arrive at the scene by 0630 and engage in salvage operations. KURETAKE will carry out screen of Sabtang South entrance and Subchaser No. 41 will furnish screen at North entrance….Convoy will take refuge in Sabtang Channel and will delay departure.”

Bashii Strait. At 0435, Hess attacks ATLAS MARU again, but misses. At 0500, POMFRET also torpedoes and damages HAMBURG MARU. At 1850, one of the escorts scuttles her at 20-18N, 121-51E.

4 November 1944:
At 1500 departs Sabtang Island.

KURETAKE takes ATLAS MARU under tow. About 1330, ATLAS MARU is beached and her cargo begins to be unloaded (by 18 November, a typhoon causes ATLAS MARU to be abandoned). Torpedo boat SAGI arrives from Takao and joins the escort.

At 1616, USN codebreakers decrypt another message from No. 1 Maritime Transport Commander that reads: “Will have Coast Defense Vessel No. 11, Minesweeper No. 20, KURETAKE and No. 3 TOYO MARU investigate the situation of ATLAS MARU and take aboard survivors from 1430 on. Transfer of victuals for the troops has already begun. Weather is generally good at the vicinity of the anchorage.”

5 November 1944:
At 0740, W-20 returns to Sabtang Island.

6 November 1944:
At 0221, departs Sabtang Island.

8 November 1944:
At 1810, arrives at Santa Cruz.

9 November 1944:
At 0626, departs Santa Cruz.

10 November 1944:
At 0918, arrives at Manila.

11 November 1944:
TOYO MARU No. 3 supplies 120 tons of coal to W-20, 80 tons to W-17 and 75 tons to W-18. At 1957, W-17, W-18 and W-20 depart Manila for Yulin, Hainan escorting convoy MAYU-10 consisting of MISAKI and SUGIYAMA MARUs. At 2315, LtCdr Robert A. Keating's USS BARBEL (SS-316) torpedoes MISAKI MARU at 15-10N, 112-40E. She sinks about two hours later. W-18 and W-20 carry out counterattacks against USS BARBEL while W-17 remains with SUGIYAMA MARU.

12 November 1944:
E of Nha Thrang, Indochina. At 0110, USS BARBEL torpedoes and sinks SUGIYAMA MARU at 15-15N, 112-10E. 15 of the crew and many of the troops being carried are killed. A total of 652 survivors from the two ships are rescued by the three warships and later landed at Yulin.

16 November 1944:
At 2200 arrives at St Jacques.

20 November 1944:
At 1205, W-17, W-18, W-20 and subchaser CH-41 departs St Jacques, Indochina escorting convoy SATA-02 consisting of HIDA MARU.

21 November 1944:
At 2030, arrives at Camranh Bay.

22 November 1944:
At 0725, departs Camranh Bay. At 1820, arrives Van Phong Bay.

23 November 1944:
At 0720, departs Van Phong Bay. At 1345, CH-41 detaches from the convoy. At 1945, arrives at Baia de Xuan Bay.

24 November 1944:
At 0746, departs Baia de Xuan Bay.

25 November 1944:
At 0800, W-20 is detached and joins the NICHINAN MARU convoy off Qui Nhon and escorts to Van Phong Bay. At 2330 arrives at Van Phong.

28 November 1944:
At 0651, departs Van Phong Bay.

29 November 1944:
At 1505 arribves at St Jacques and at 1900 arrives at Saigon.

E 2 December 1944:
W-20 joins convoy MASHI-12A consisting of two unidentified merchant ships escorted by subchaser CH-1.

E 4 December 1944:
Arrives at Singapore.

30 December 1944:
At 0830 departs Seletar and off Singapore begins escorting convoy SHISA-32 consisting of TOYU, OTSUSAN and SAN LUIS MARUs and two unidentified merchant ships as well as patrol boat PB-104 and three unidentified escorts (probably same escorts as for SASHI-39).

4 January 1945:
At 0720 arrives at St Jacques.

6 January, 1945:
At 0300 W-20 departs St Jacques with patrol boat PB-104, auxiliary minesweeper Wa-9, auxiliary subchasers KYO MARU No. 13 and TOKACHI MARU escorting convoy SASHI-39 consisting of SHINYU MARU and nine unidentified merchant ships.

9 January, 1945:
At 1700 arrives at Singapore.

12 January, 1945:
At 0300, W-20, and minelayer YURISHIMA depart Cape St. Jacques for Singapore escorting convoy SASHI-30 consisting of SHINGI, HOKOKU and FRANCE MARUs and FUSHIMI MARU No. 2 and KYOEI MARU No. 7.

About 0730, a carrier-type aircraft appears and drops a star shell over the convoy, then withdraws. The convoy proceeds at 8 knots. About 1100, three Grumman F6F "Hellcat" fighters bomb and strafe the ships. At 1200, four more aircraft dive-bomb and strafe while the ships return fire. At 1220, SHINGI MARU is hit portside blowing a large hole in her hull. At 1310, Abandon Ship is ordered. By 1320, her list increases and SHINGI MARU capsizes and sinks at 09-24N, 106-44E. She was carrying 1,266 Army troops, aviation spares and bombs. 38 crew and 790 soldiers are KIA.

The convoy reverses course towards Cape St. Jacques. About 1400, KYOEI MARU No.7 is hit by bombs and sinks with hands. FRANCE MARU, carrying the 3rd Shipping Transport Headquarters and 70th Anchorage Headquarters troops, is also bombed and damaged, but manages to beach herself. Fires rage and she is abandoned. FUSHIMI MARU No. 2 and HOKOKU MARU are damaged, but reach Cape St. Jacques the same day. The convoy is disbanded.

15 January 1945:
At 1100 W-20 arrives back at the Singapore eastern anchorage. Undergoes repairs for most of the month.

31 January 1945:
At 0800, W-20 kaibokan KANJU and MIYAKE depart Singapore escorting convoy HI-88C consisting of transport OESAN MARU and tanker ENCHO MARU.

4 February 1945:
The convoy arrives at Poulo Dama, French Indo Chinsa.

5 February 1945:
At 0500 the convoy departs.

8 February 1945:
In the evening, the convoy arrives and anchors Quinhon Bay, Indochina.

9 February 1945:
In the early morning, the convoy departs Quinhon Bay.

12 February 1945:
At 1800, arrives at Zensui Bay, China.

13 February 1945:
At 0500, the convoy departs Zensui Bay.

16 February 1945:
The convoy, arrives at Quemoy.

17 February 1945:
In the early morning, departs Quemoy. That evening, arrives at Nanji Island.

18 February 1945:
At 0700, departs Nanji Island.

21 February 1945:
The convoy arrives at the mouth of the Yangtse River. ENCHO MARU, MIYAKE and W-20 are detached and arrive at Shanghai later that day. ENCHO MARU discharges 3500 tons of fuel oil, or half, of her cargo.

26 February 1945:
At 1000, W-20, and kaibokan MIYAKE depart Shanghai escorting the Encho Maru convoy consisting of tanker ENCHO MARU .

27 February 1945:
Arrives at Oryong Do (Gyoryo To), Chosen.

28 February 1945:
Departs Oryong Do.

1 March 1945:
At 2000 arrives at Fukuoka Wan.

2 March 1945:
At 0600 departs Fukuoka Wan and at 1330 the convoy succesfully arrives at Moji. ENCHO MARU discharges the remaining 3500 tons of her oil cargo plus some raw rubber.

1 May 1945:
Reserve Lt Yamada Kunio (former CO of KIRI MARU No. 5) is appointed Commanding Officer.

5 May 1945:
Yellow Sea. 140 miles SE of Mokpo, Korea. W-20 proceeds to the scene of the sinking of kaibokan OJIKA, sunk by USS SPRINGER (SS-414) on 2 May 1945, but W-20 is intercepted enroute by LtCdr Allen R. Faust's USS TREPANG (SS-412) that torpedoes and sinks her at 33-56N, 122-49E.

30 November 1945:
Removed from the Navy List.

Author's Notes:
[1] USS FLIER, while transiting the Balabac Strait, Philippines, on 13 August 1944 struck a mine and sank. Fourteen of 86 crewmen escaped, but only eight survived the long swim in the Sulu Sea to shore. After making their way by raft to Palawan, at the end of the month they were evacuated by USS REDFIN (SS-272). In the spring of 2009, a dive team from YAP Films located the wreckage of the submarine at a depth of 330 feet. On 1 February 2010, the USN confirmed that the submarine is USS FLIER.

Little data were found of W-20's movements during Sep '42 - Mar '44. Readers with access to such data are requested to post the information on the Discussion and Questions board or at's IJN Ship Message Board

Thanks go to Mr. Aki of Japan and Matthew Jones of Missisippi, USA for help in identifying COs. Thanks also go to the late John Whitman of Virginia, USA for info on CNO intercepts of Japanese messages, and to Mr. Gilbert Casse of France for general assistance.

Photo credit goes to Ships of the World (SOTW) via J. Ed Low.

-Bob Hackett and Peter Cundall.

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