Japanese Minesweepers

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

IJN Minesweeper W-20: Tabular Record of Movement
© 2005-2018 Bob Hackett and Peter Cundall
Revision 17

19 March 1941:
Tokyo. Laid down at Ishikawajima Shipbuilding.
5 August 1941:
Classified as a type seven minesweeper and named W-20 under instruction No. 246.
17 September 1941:
Launched and numbered W-20.
1 December 1941:
Her assigned call sign is JXTP.
10 December 1941:
Reserve Lt Kita Yasaburo is appointed appointed Chief Equipping Officer.
15 December 1941:
Completed and commissioned in the IJN. Registered in the Maizuru Naval District and attached to the Combined Fleet Third Fleet Second Base Force. 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.
28 January 1942:
At Balikpapan, at 1300, receives 120 rounds main gun ammunition from patrol boat PB-37.
10 March 1942:
Attached to the Combined Fleet Fourth Fleet Eight Special Base Force.
31 March 1942:
W-20 is coaled by auxiliary gunboat NIKKAI MARU.
1 April 1942:
Reclassified as a type nineteen minesweeper.
21 April 1942:
At Rabaul, refueled by IJN auxiliary transport KAGU 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.
From 0830 till 0920 W-20 is alongside auxiliary ammunition ship KOTOKU MARU and is supplied with coal.
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.
24 December 1942:
Attached to the Combined Fleet Southeast Area Fleet Eight Fleet First Base Force.
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. Later that day 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.
12 February 1943:
Departs Rabaul on an escort mission.
17 February 1943:
Returns 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.
12 March 1943:
Departs Rabaul on an escort mission, probably of NOSHIRO MARU.
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. Attached to the Mako Guard District Forces Mako Special Base Force In Service as a security minesweeper and reattached to Kirun Defense Forces.
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.
3 June ~ 5 June 1943:
Takes part in combined exercise No. 13.
23 June ~ 25 June 1943:
Takes part in combined exercise No. 14.
4 July 1943:
Rescues survivors from sunk IJA auxiliary transports KOKI MARU and damaged ATLANTIC MARU.
8 July ~ 10 July 1943:
Takes part in combined exercise No. 15.
10 July 1943:
Scheduled to depart Kirun, Formosa (now Keelung, Taiwan) and escort TSUYAMA MARU.
15 July 1943:
Attached to the Maizuru Naval District.
16 July 1943:
Departs Takao, Formosa (now Kaoshiung, Taiwan) for Kirun.
24 July 1943:
Departs Kirun and meets up with and starts escorting convoy No. 283 consisting of KINREI, SHONAN, TOFUKU and HAGURO MARUs and KYOEI MARU No. 5. and four unidentified marus, escorted by patroal boat PB-36.
28 July 1943:
Arrives at Moji with convoy No. 283.
28 ~ 29 July 1943:
Departs Moji.
29 July 1943:
Arrives at Maizuru.
17 September 1943:
Attached to the Chinkai Guard District Forces.
18 September 1943:
Departs Maizuru for Chinkai, Chosen (now Jinhae, South Korea).
2 December 1943:
Arrives at Chinkai.
3 December 1943:
Loads fuel.
4 December 1943:
Provisioned with fresh food and water.
5 December 1943:
Departs Chinkai and arrives at Takeshiki, Tsushima and departs later that day.
7 December 1943:
Arrives Miura Bay, Korea and departs later that day.
8 December 1943:
Arrives at Takeshiki. Loads coal.
10 December 1943:
Departs Takeshiki on anti-submarine sweep.
13 December 1943:
Arrives at Miura Bay.
14 December 1943:
Departs Miura Bay on an escort mission.
15 December 1943:
Arrives at Chinkai. Loads fuel and is provisioned with fresh food and water and departs later that day on a submarine hunt.
18 December 1943:
Detects an enemy submarine, drops 28 depth charges.
19 December 1943:
Arrives at Chinkai.
20 December 1943:
Bunkers (Refuels).
21 December 1943:
Provisioned with fresh food and stored grain products.
22 December 1943:
Departs Chinkai on patrol. Inspects a Junk and later that day returns to port.
23 December 1943:
Unloads shell gunpowder.
24 December 1943:
Departs Chinkai and later that day arrives at Fuzan (Pusan), Korea. Docks at the Chosen heavy industry company's second dock.
30 December 1943:
Undocked. Departs Fuzan and arrives at Chinkai later that day. Loads shell gunpowder.
31 December 1943:
Departs Chinkai.
3 January 1944:
Arrives at Takeshiki.
4 January 1944:
Loads coal and departs Takeshiki.
5 January 1944:
Arrives at Miura Bay.
6 January 1944:
Departs Miura Bay and arrives at Mutsure Jima latyer that day.
8 January 1944:
Departs Miura Bay to assist a ship in distress. Starts towing but the towing line breaks.
10 January 1944:
Arrives at Chinkai, takes on bunkers, water and supplies and fresh food and then departs on an anti-submarine sweep.
13 January 1944:
Arrives at Chinkai.
14 January 1944:
Bunkers.
15 January 1944:
Provisioned with fresh food and water.
16 January 1944:
Departs Chinkai for a patrol and arrives at Takeshiki later that day.
19 January 1944:
Arrives at Takeshiki.
20 January 1944:
Loads coal.
22 January 1944:
Departs Takeshiki.
25 January 1944:
Arrives at Chinkai.
26 January 1944:
Takes on fresh water.
27 January 1944:
Loads fuel and is provisioned with fresh water.
28 January 1944:
Departs Chinkai on patrol.
31 January 1944:
Arrives at Takeshiki.
1 February 1944:
Loads coal.
3 February 1944:
Departs Takeshiki.
6 February 1944:
Arrives at Chinkai.
7 February 1944:
Takes on fuel and water.
10 February 1944:
Provisioned with fresh food.
12 February 1944:
Departs Chinkai on patrol 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:
Loads coal. Departs Takeshiki on an anti-submarine sweep.
24 February 1944:
Arrives at Chinkai.
25 February 1944:
Loads fuel and is provisioned with water.
29 February 1944:
Provisioned with fresh food.
1 March 1944:
Departs Chinkai on ferry escort.
3 March 1944:
Joins and escorts an Army convoy consisting of one ship from Fuzan to Moji.
4 March 1944:
Resumes patrol and later that day arrives at Takeshiki. Loads coal.
5 March 1944:
Departs Takeshiki.
7 March 1944:
Arrives at Yokosuka.
8 March 1944:
Loads depth charges and fuel and is provisioned with fresh water, fresh food and canteen goods.
9 March 1944:
Departs Yokosuka and arrives at Kisarazu later that day.
10 March 1944:
Loads heavy oil.
12 March 1944:
W-20 departs from nearby Kisarazu on an escort mission.
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. Loads fuel and is provisioned with fresh food and water.
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 and returns to Saipan later that day.
23 March 1944:
Bunkers and loads stores.
27 March 1944:
Transfers ammunition to a military unit.
28 March 1944:
At 0500 W-20 departs Saipan for Yokosuka escorting convoy No. 4328 consisting of IKUSHIMA and KEIYO MARUs.
30 March 1944:
USS STINGRAY torpedoes and sinks IKUSHIMA MARU at 20-43N, 143-04E. W-20 drops depth charges with no result. Rescues 45 survivors. Auxiliary minesweeper TAKUNAN MARU No. 8 later joins the convoy.
April 1944:
Lt Tanaka Sanzo assumes command.
4 April 1944:
At 2133, arrives at Yokosuka.
9 April 1944:
Scheduled to escort convoy Higashi-Matsu No. 6.

12 April 1944:
Loads coal and is provisioned with water.
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, kaibokan CD-6 and subchasers CH-10 and CH-12 escorting convoy "Higashi-Matsu No. 6" consisting of AWAJI, HAKUBA, KATSUKAWA, TAKAOKA, BATAVIA, NITCHO, 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.
20 April 1944:
At 0812, an enemy submarine is detected. At 0842, drops 5 depth charges. At 0903, an airplane drops bombs. At 0905, drops 8 depth charges. At 0914, CD-6 drops depth charges and an airplane drops bombs.
21 April 1944:
At 1800, CH-10 joins the submarine hunt.
22 April 1944:
At 2120 drops 8 depth charges.
23 April 1944:
At 0300, TONEGAWA and INARI MARUs together with UZUKI, SARUSHIMA and W-20 are detached from the convoy and at 1735 arrive at Guam.
25 April 1944:
At 0016, departs Guam in a convoy also escorted by minelayer SARUSHIMA consisting of TONEGAWA MARU. At 1836 arrives at Saipan.
26 April 1944:
Loads coal, heavy oil and is provisioned with water.
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 submarine chaser CH-10.
3 May 1944:
At 1845, MIYAKE carries out a depth charge attack.
4 May 1944:
At 1400, a floating mine is discovered. At 1553, destroys the floating mine at 255 degrees 8.5 nautical miles off Oshima Lighthouse. At 2130, arrives at Yokosuka.
5 May 1944:
At 0627 departs Yokosuka roadstead and at 0730, arrives at Yokosuka.
6 May 1944:
Loads coal, heavy oil and depth charges and is provisioned with water.
9 May 1944:
Loads fresh food and canteen goods.
15 May 1944:
At 0900, departs Yokosuka. At 1143 arrives off Tateyama.
16 May 1944:
Off the coast of Tateyama on a parallel course with the convoy carries out communication exercises.
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.
26 May 1944:
Loads coal and heavy oil.
27 May 1944:
At 1730, embarks 119 passengers (Guam army soldiers).
28 May 1944:
At 0245, W-20, minelayer SARUSHIMA and auxiliary minesweeper FUMI MARU No. 2 depart Saipan escorting Hinko Maru convoy (No. 3515) consisting of REIKAI and HINKO MARUs. At 1422, detects an enemy submarine. At 1429, drops 5 depth charges. Later that day arrives at Guam. At 1915, 119 passengers disembark.
29 May 1944:
At 0400, W-20, kaibokan CD-12, minelayer SARUSHIMA and auxiliary minesweeper FUMI MARU No. 2 depart Guam escorting Batavia Maru 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:
At 2043, a surfaced enemy submarine is detected. Together with HATAKAZE pursues the submarine. At 2135, carries out an anti-submarine sweep in the vicinity where the submarine submerged. 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. At 2240, W-20 rejoined with convoy No. 4530. At 2315, at 270 degree bearing discovers a surfaced submarine. Starts pursuing. At 2353, at a distance of aproximately 6,000m guns fired one round. At 2354, the enemy submarine is submerged. At 2400, drops 5 depth charges. W-20 and the other escorts counter-attack and drop a total of thirty-nine depth-charges, but without damage to USS SHARK.
3 June 1944:
At 0007, stops dropping depth charges. Sweeps the vicinity where the submarine submerged. Following of the convoy stops. At 0500, Continues sweeping. At 0952 rejoins convoy No. 4530.
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 fired. At 0415, HAKUSAN MARU’s stern rises vertically and she sinks at 22-37N 136-50E. At 0410, drops depth charges. At 0435, drops depth charges. Following of the convoy stops. At 0588, continues sweeping. W-20 and the other escorts counter-attack and drop thirty-four depth-charges, but without damage to USS FLIER. At 0735, rejoins convoy No. 4530. [1]
6 June 1944:
At 1900, on a forward patrol, 5000m in front of the convoy.
7 June 1944:
At 0430, ends the forward patrol, and rejoins the convoy.
8 June 1944:
At 0640, as the escort mission ends W-20 is at the end of the convoy column. At 0800, the remainder of the convoy arrives at Yokosuka.
9 June 1944:
Loads heavy oil, shell gunpowder cartridges and is provisioned with water.
10 June 1944:
At 1615, enters Yokosuka Naval Dockyard second dock.
19 June 1944:
At 0923, departs Yokosuka Naval Dockyard. Loads shell gunpowder.
20 June 1944:
Loads fuel and 20 type two depth charges.
21 June 1944:
Departs Yokosuka for a trial and returns later that day.
22 June 1944:
Loads heavy oil and is provisioned with fresh food.
23 June 1944:
Loads coal and is provisioned with water.
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 Kominato, Hachijo Jima.
25 June 1944:
Arrives at Kominato. Later departs Kominato for an anchorage patrol.
26 June 1944:
Returns at Kominato. Later departs Kominato for an anchorage patrol.
27 June 1944:
Returns at Kominato. Later departs Kominato for an anchorage patrol.
28 June 1944:
Returns at Kominato. Later departs Hachijo Jima escorting a convoy consisting only of UNKAI MARU No. 10 bound for Yokosuka.
29 June 1944:
Arrives at Yokosuka.
30 June 1944:
Loads fuel and is provisioned with water.
1 July 1944:
Loads heavy oil.
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. Later departs for an anchorage patrol. 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. With SHIBAZONO MARU detaches from convoy No. 3702 and joins convoy No. 3701 bound for Yokosuka. At 1825, emergency anchoring.
5 July 1944:
Arrives at Yokosuka. Loads coal and is provisioned with water.
6 July 1944:
At 0100, departs Yokosuka escorting convoy 3706.
8 July 1944:
At 1128, arrives off the coast of Mutsure Jima. Departs at 1752.
9 July 1944:
At 0610, arrives at Chinkai.
10 July 1944:
Loads coal.
11 July 1944:
At 0801, departs Chinkai on patrol.
12 July 1944:
Arrives at West Gyuji Island, Chosen (now South Korea).
13 July 1944:
Departs West Gyuji Island. At 1000 arrives at rendezvous point (35-05N 125-10E). Starts a vicinity search. At 1448, emergency anchoring at Shimizu. Later departs Shimizu for an anti-submarine sweep.
16 July 1944:
At 1457, arrives Moppo, Chosen (now Mokpo, South Korea).
17 July 1944:
Loads coal and is provisioned with water.
19 July 1944:
At 1155, departs Moppo. At 1700, on patrol. At 1710, discovers a floating mine. At 1810, destroys the floating mine with gunfire. Later arrives at Anba To, Chosen (now South Korea).
20 July 1944:
Departs Anba To for a patrol and arrives at Soto Kemuri Shima, Chosen (now South Korea) later that day.
21 July 1944:
Departs Soto Kemuri Shima. At 1400, discovers a floating mine. At 1613, destroys the floating mine with gunfire. At 1836, discovers another floating mine. At 2025 destroys the floating mine with gunfire. Arrives at Kogunsan Gunto, Chosen (now South Korea) later that day.
22 July 1944:
Departs Kogunsan Gunto for a patrol. At 0817, discovers two floating mines. At 0936, destroys the floating mines with gunfire. At 0957, discovers a floating mine. At 1034, destroys the floating mine with gunfire. At 1250, discovers a floating mine. At 1330, the floating mine is blown up. At 1429, discovers a floating mine. At 1534, the floating mine is blown up. At 1920, anchors at Sakurajima (Anba To).
23 July 1944:
At 0555, departs Sakurajima. At 0930, discovers a floating mine. At 0950, destroys the floating mine with gunfire. At 1150, discovers a floating mine. At 1243, destroys the floating mine with gunfire. At 1558, discovers two floating mines. At 1628, one floating mine is blown up. At 1721, the other floating mine is destroyed with gunfire. Arrives at Daikokuyama Shima, Chosen (now South Korea) later that day.
24 July 1944:
Departs Daikokuyama Shima with auxiliary subchaser Cha-76 for an anti-submarine sweep. At 1334, a floating mine is discovered. At 1424, the floating mine is destroyed with gunfire. At 1445, started sweeping for mines. At 1845, a floating mine is discovered. At 1914, the floating mine is destroyed with gunfire.
25 July 1944:
At 1251, arrives at Chinkai.
26 July 1944:
Loads coal and heavy oil.
28 July 1944:
At 0355, departs Chinkai. At 1602 arrives at Moji at quay seven.
31 July 1944:
At 1604, departs Moji and at 1704 arrives off the coast of Mutsure Jima.
1 August 1944:
At 0400, departs departs off the coast of Mutsure Jimain convoy MO-05 consisting of KAZUURA, TATSUJU, TSUSHIMA, YAMAHAGI, GYOKU, ETAJIMA and HIROTA MARUs also escorted 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. At 1530, transfers reserve bank notes of the Shanghai bank to destroyer HIBIKI. At 1745, collides with the bow of the army auxiliary transport YAMAHAGI MARU. At 1800, the right anchor is entangled in YAMAHAGI MARU’s right anchor chain. At 1830, the right anchor chain is cut.
8 August 1944:
The anchor chain is being repaired. Repairs are completed at 1630.
9 August 1944:
At 1640, departs Naha having detached from convoy.
11 August 1944:
At 1108, arrives at Moji. Loads heavy oil.
12 August 1944:
Loads coal.
14 August 1944:
Provisioned with fresh food and water. 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:
At 1200 anti-submarine sweep towards Kirun. Arrives at Keelung at 1400.
26 August 1944:
Loads coal.
27 August 1944:
At 0900 departs Keelung escorting convoy MOTA-23.
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, Niihama quay later that day. Loads coal.
30 August 1944:
At 1900 arrives at Takao.
31 August 1944:
Departs Takao with CH-41 on a relief mission towards convoy MI-15. At 1900, LtCdr (later Rear Admiral) Eugene B. Fluckey's USS BARB (SS-220) torpedoes and sinks the 45th Minesweeper Squadron's HINODE MARU No. 20. At 1944, starts an anti-submarine sweep near the sinking location.
1 September 1944:
Torpedoboat HIYODORI and subchaser CH-41 carry out an anti-submarine sweep. At 1900 the sweeping ends.
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. Loads heavy oil and coal.
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:
At 1440, at 30 degrees right bearing 8000m friendly aircraft drop bombs. At 1450, carries out an anti-submarine sweep and drops depth charges. At 1612, stops following convoy MI-17 and starts an anti-submarine sweep. At 1740, rejoins the convoy. 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. KOGYO MARU has rejoined convoy. The convoy reforms and adopts a zig zag formation. At 1034, together with W-17 and CH-41 is detached from convoy MI-17 and they head towards Takao. 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 0326, drops 9 depth charges. At 0635, CD-1 and CD-3 rescue survivors. At 0738, W-17 and CH-41 start an anti-submarine sweep. At 0330 follows the fleet again and continues to escort. At 0908, 2500m from the bow a friendly aircraft drops three bombs. At 0912, drops 9 depth charges. At 1135, stops following the convoy and starts an anti-submarine sweep. 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. Arrives at Lapoc Bay.
12 September 1944:
At 1930, convoy TAMA-25 anchors at Santa Cruz. Meanwhile at 1200 W-20 arrives at Saei, Formosa (now Zuoying, Taiwan). At 1027, anchors. At 1308, loads heavy oil. Later departs Saei and arrives at Takao later that day.
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. Meanwhile W-20 loads coal.
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 1000 embarks 250 army soldiers and at 1200 W-20 departs Takao to rejoin the convoy. Arrives at Daihanratsu, Formosa (now Taiwan) later that day.
15 September 1944:
Departs Daihanratsu and at 0900 apparently meets up with the convoy. At 1200 arrives at Basco and at 1834, disembarks the army soldiers. Departs Basco later that day.
16 September 1944:
At 1147 arrives at Takao. Loads coal and heavy oil.
17 September 1944:
Loads coal.
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. Arrives at Daihanratsu later that day.
19 September 1944:
Departs Daihanratsu. At 1633, a friendly aircraft drops bombs at 70 degrees left bearing, 2000m. Drops 9 depth charges. At 1640, a friendly aircraft drops a bomb at 25 degrees right bearing 5000m. At 1644, drops 11 depth charges. At 1847 rejoins the convoy. At 2130, the convoy arrives at Sabtang anchorage, Philippines. Patrols the anchorage entrance.
20 September 1944:
At 0345, the convoy departs Sabtang and continues with escort. At 1156, a friendly aircraft dops a bomb at 30 degrees right bearing 3500m. Stops following the convoy. At 1234, carries out an anti-submarine sweep. At 1618, rejoins the convoy. They arrives at Musa Bay, Philippines later that day.
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 1630, stops rescuing survivors and heads towards auxiliary transport TOYO MARU No. 3. At 1652, a friendly aircraft drops a bomb at 1800m. At 1653, drops 9 depth charges. At 2215, the convoy arrives at Lapoc Bay.

22 September 1944:
At 1035, disembarks the rescued survivors.
23 September 1944:
Off the coast of Lapoc patrols the Lapoc Bay entrance.
24 September 1944:
Replaced by CH-41. At 1030, arrives at Lapoc. Departs at 1858.
25 September 1944:
Off the coast of Lapoc patrols the Lapoc Bay entrance.
26 September 1944:
At 0630, convoy TAMA-26 departs Lapoc Bay and continues with escort. At 1645, arrives at North San Fernando.
27 September 1944:
At 0930, alongside auxiliary tanker NICHINAN MARU (1945 grt) and is supplied with heavy oil. At 1750, alongside auxiliary army transport SHIRANESAN MARU and is supplied with coal.
28 September 1944:
At 0147, departs San Fernando on a rescue mission towards convoy MIMA-11. At 1000 arrives at Santa Cruz. At 1707 departs Santa Cruz for San Fernando.
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 1440, drops 5 depth charges. At 2056 arrives at Manila Bay.

2 October 1944:
At 0015 emergency anchoring off the coast of Manila. At 0643 anchors. Later that day arrives at Manila. Loads coal and heavy oil and is provisioned with water.
3 October 1944:
Provisioned with water. At 1555 departs Manila and arrives off the coast of Corregidor later that day.
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 (2764 gt), HOKUREI, TERUKUNI and HISHIGATA MARUs and SHINYO MARU No. 8. Departs off the coast of Corregidor to join convoy MATA-28. At 0100, the convoy departs. At 1055, enemy submarine threat forces the convoy to stop at Iba anchorage, Philippines. Carries out an anti-submarine sweep. At 1400, carries out an anti-submarine sweep towards Santa Cruz. At 1908 the convoy arrives 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. At 1845, carries out an ant-submarine sweep. At 2350, patrols the Lapoc Bay entrance.

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. At 0224, the convoy departs. At 0250 stops following the convoy for a patrol. At 0634 rejoins the convoy. At 0900, joins CD-25 and CD-32. Together they head towards the meeting point with auxiliary transport KAMOI.

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. At 1005, CD-8 joins the escort. At 1030 the convoy is heading to Hong Kong. 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. Provisioned with fresh food.
12 October 1944:
Loads coal and is provisioned with water.
13 October 1944:
Loads heavy oil.
14 October 1944:
Departs Hong Kong and arrives at Junk Bay, Hong Kong later that day.
15 October 1944:
Departs Junk Bay and arrives at Hong Kong later that day.
15 October 1944:
Provisioned with water.
16 October 1944:
At 1540 undergoes an air attack. The twelve centimeter gun fires 11 rounds and the twenty-five millimeter machine gun fires 1149 rounds.
17 October 1944:
Depart Hong Kong and arrives at Junk Bay later that day.
18 October 1944:
Departs Junk Bay and arrives at Hong Kong later that day.
19 October 1944:
Depart Hong Kong and arrives at Junk Bay later that day.
20 October 1944:
Departs Junk Bay and arrives at Hong Kong later that day. Loads coal and is provisioned with water.
21 October 1944:
Provisioned with fresh food.
26 October 1944:
Provisioned with water.
27 October 1944:
Depart Hong Kong and arrives at Junk Bay later that day. At 1958, W-20, subchasers CH-30, CH-33 and auxiliary subchaser and CHa-41 depart Junk Bay near 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:
Convoy HOMA-1 arrives at Saei (Takao outer harbor fleet anchorage). The convoy departs Saei later that day and at 1358, arrives at Takao. W-20 anchors at Niihama quay. Loads heavy oil and is provisioned with fresh water.
31 October 1944:
Loads coal and depth charges and is provisioned with fresh food, canteen goods and stored grain products. At 1410, W-21 is alongside.
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.
2 November 1944:
At 2305 HAMBURG and ATLAS MARUs are torpedoed and are unable to continue.
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 USS BREAM (SS-243), LtCdr William T. Kinsella’s USS RAY (SS-271), LtCdr Maurice W. Shea’s USS RATON (SS-270) and LtCdr (later Captain) Enrique D. Haskins’ USS 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). At 0100, the convoy heads towards Sabtang. W-20 patrols the North entrance. At 0905, departs for a rescue mission. At 1301 alongside ATLAS MARU and takes 674 people on board. At 1450, returns to Sabtang anchorage and transfers the 674 rescued people to auxiliary tanker ASOKAWA MARU. At 1650, departs because of a submarine threat. At 1655, KURETAKE tows ATLAS MARU. Provides escort 3000m ahead of them. Later that day arrives at Sabtang anchorage. 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, USS POMFRET also torpedoes and damages HAMBURG MARU. At 1850, one of the escorts scuttles her at 20-18N, 121-51E.
4 November 1944:
Patrols Sabtang west entrance. After completing the patrol returns towards Sabtang anchorage. 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 0720 departs Sabtang anchorage for a patrol mission. At 0740, W-20 returns to Sabtang Island.
6 November 1944:
At 0221, departs Sabtang Island. At 0340 convoy MOMA-06 departs Sabtang anchorage for Manila. At 1435, a sweeping force joins the convoy and takes up posion ahead of the convoy.
8 November 1944:
At 0700, the sweeping force discovers an enemy submarine at 160 degrees 10000m. At 0759, torpedo boat SAGI is torpedoed. At 0849, SAGI sinks. At 1810, arrives at Santa Cruz. At 1830 alongside auxiliary transport TOYO MARU No. 3 and loads coal. At 2355, loading coal is completed.
9 November 1944:
At 0027 disengages. At 0626, departs Santa Cruz escorting convoy MOMA-06. Arrives off the coast of Manila later that day.
10 November 1944:
At 0918, arrives at Manila. Loads heavy oil.
11 November 1944:
At 0855, alongside TOYO MARU No. 3 and loads 120t coal. At 1150, loading coal is complete and disengages. TOYO MARU No. 3 also supplies 80 tons of coal to W-17 and 75 tons of coal to W-18. At 1202 anchors. At 2200 provisioned with fresh water. 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.
14 November 1944:
At 2315 MISAKI MARU is torpedoed. Carries out an anti-submarine seep. Drops 5 depth charges.
15 November 1944:
At 0025, MISAKI MARU sinks. W-20 stops following the convoy. At 0206, starts an anti-submarine sweep. At 0320, SUGIYAMA MARU is torpedoed and sinks. Carries out an anti-submarine sweep. Drops 5 depth charges. At 0950, stops sweeping and heads towards St. Jacques.
16 November 1944:
At 2200 arrives at St Jacques.
17 November 1944:
Departs St. Jacques and arrives at Saigon, French Indochina (now Vietnam) later that day. Loads heavy oil.
18 November 1944:
Loads coal and is provisioned with water.
20 November 1944:
Departs Saigon. At 1205, W-17, W-18, and subchaser CH-41 departs St Jacques, Indochina escorting convoy SATA-02 consisting of HIDA MARU.
21 November 1944:
At 1030 joins the escort of convoy SATA-02 consisting of HIDA MARU escorted by W-17, W-18 and Ch-41. 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 0823, at Cape Batanga, 15-20N 109-10E, W-20 is detached and joins the NICHINAN MARU (5175 gt) 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 escorting NICHINAN MARU. At 1630, off the coast of Qui Nhon is detached.

29 November 1944:
At 1505 arribves at St Jacques and at 1900 arrives at Saigon.
30 November 1944:
Loads coal and is provisoned with fresh water.
3 December 1944:
At 0615 W-20 joins convoy MASHI-12A consisting of two unidentified merchant ships escorted by subchaser CH-1.
4 December 1944:
Arrives back at St. Jacques.
9 December 1944:
At 1100, before the heaquarters W-21 is alongside.
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).
1 January 1945:
Departs St. Jacques.
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.
11 February 1945:
At 1200 W-20 arrives briefly at Yulin, possibly separate from the convoy.
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.
3 March 1945:
W-20 departs Moji.
4 March 1945:
Arrives at Maizuru. Docked.
28 March 1945:
Departs Maizuru.
30 March 1945:
Arrives at Chinkai.
1 April 1945:
At 2350 arrives at Hikin Do.
2 April 1945:
At 1630 departs Hikin Do with kaibokan CD-215 on an anti submarine sweep.
8 April 1945:
At 1110 arrives back at Hikin Do.
9 April 1945:
At 0800 transfers from Hikin Do to Moppo (Mokpo).
12 April 1945:
At 1255 transfers from Moppo to Hikin Do. At 1434 departs Hikin Do on patrol.
19 April 1945:
At 1735 begins escorting convoy MO-705 Part 1 with kaibokan OKI, destroer KURI, gunboat OKITSU, auxiliary submarine chasers CHa-220 and CHa-240 and submarine chaser CH-21. The convoy consists of YAMAZONO, AWA, TOYOKAWA, SHINYO and KEIZO (KEIJO?) MARUs.
20 April 1945:
At 1330 the convoy arrives at Daito Wan and departs at 1500.
21 April 1945:
At 1155 CH-21 and W-20 are detached.
22 April 1945:
At 1640 CH-21 and W-20 arrive at Daito Wan.
24 April 1945:
At 1025 CH-21 and W-20 depart Daito Wan.
25 April 1945:
At 1110 the ships arrive at Hikin Do. At 1230 W-20 transfers to nearby Moppo.
28 April 1945:
At 1335 transfers from Moppo to Hikin Do.
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 May '43 - Dec '43. Readers with access to such data are requested to post the information on the Discussion and Questions board or at j-aircraft.org'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 and Mr. Berend van der Wal of Netherlands 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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