ZATSUYOSEN!

(SENKO MARU prewar)

IJN SENKO MARU:
Tabular Record of Movement

© 2011-2018 Gilbert Casse, Bob Hackett and Peter Cundall

Revision 2

12 September 1934:
Yokohama. Laid down at Yokohama Dock K.K. as a 4,472-ton cargo ship for Kinkai Yusen K. K. (Near Seas Mail Co.), Tokyo.

18 May 1935:
Launched and named SENKO MARU.

31 July 1935:
Completed and registered in Tokyo. Her registered net tonnage is 2,621-tons and her registered draft (light), 23.9’. Placed in Kinkai Yusen's Takao ~ Tokyo commercial service, transporting bananas and other fruits from Formosa to the Keihin (Tokyo – Kawasaki – Yokohama) area.

E 1936:
Registered net tonnage is changed to 2,618-tons.

E 1937:
Registered draft (light) is changed to 16.7’.

8 September 1939:
Her ownership changes to Nippon Yusen K.K.

16 August 1941:
SENKO MARU is scheduled to be requisitioned by the IJN under internal order No. 874.

21 August 1941:
Requisitioned by the IJN.

20 September 1941:
SENKO MARU is registered in the IJN as an auxiliary transport under internal order No. 1093 and attached to the Sasebo Naval District. Her homeport is Sasebo Naval Base. Enters Osaka Tekkosho (Ironworks) K.K., Innoshima shipyard to start her military conversion.

14 November 1941:
Conversion is completed. Attached to the Fifth Fleet as an auxiliary transport, (Ko) category. [1]

3 December 1941:
Departs Sasebo for Nagakasuku Wan (Bay), Okinawa.

8 December 1941:
Arrives at Nagakasuku Wan. Departs later for Koniya, Amami-Oshima where she arrives at an unknown date.

17 December 1941: The Invasion of Lamon Bay, Southern Luzon:
Imperial General Headquarters launches the combined IJA and IJN Lamon Bay Operation. The Army force consists of Gen (later Field Marshal) Count Terauchi Hisachi’s Southern Expeditionary Army. Its 14th Army, under LtGen Homma Masaharu, fields MajGen Morioka Susumu's Invasion Unit of about 7,000 troops consisting of elements of the 16th Infantry division: 20th Infantry, 22nd Field Artillery, HQ and II Battalion, 16 HQ Company, 16th Eng Battalion, 16th Recon Battalion, 3/45 AA Company, 16th Transport, 16th Signal Company, 16th Med Unit and 16th Veterinary Unit. Two AA and one Signals regiments are stationed on IJA transports.

The invasion units are embarked on 20 IJA transports: BENGAL, DAINICHI, DURBAN, KAIMEI, KAYO, KITANO, KOFUKU, LISBON, NAGATO, NICHIREN, RYOKA, RYUYO, SHINSEI, SHINSHU (4182 GRT), TAIAN, TATSUNO, TOFUKU, TOYAMA and TOYOHASHI MARUs and TAMON MARU No. 5.

The naval force consists of Vice Admiral (later Admiral) Kondo Nobutake's (35)(former CO of KONGO) Southern Force, Philippines Invasion Group that includes Vice Admiral Takahashi Ibo’s (35)(former CO of YAMASHIRO) Third Fleet. Rear Admiral (later Vice Admiral) Kubo Kyuji’s (38) (former CO of KAGA) Invasion Unit consists of his 1st Base Force HQ, in light cruiser NAGARA, 1st Quartermaster Ports and Docks Unit and 1st Naval Signal Unit, aboard HAKUSAN MARU, 1st Naval Guard Unit, aboard KIMISHIMA MARU, 1st Naval Survey Unit in SENKO MARU and Captain (later Vice Admiral) Mori Kunizo's (40)(former CO of SATA) Sasebo No. 1 and 2 Combined Special Naval Landing Force (SNLF) aboard MYOKO MARU.

The convoy’s escort consists of light cruiser NAGARA (F), heavy cruiser ASHIGARA, destroyers TOKITSUKAZE, YUKIKAZE, KAWAKAZE, SUSUKAZE, UMIKAZE, YAMAKAZE, minelayer AOTAKA, minesweepers W-7 and W-8, auxiliary gunboat/minelayer IKUSHIMA MARU, auxiliary gunboats BUSHO, KEIKO, KANKO and MYOKEN MARUs, auxiliary subchasers SHONAN MARU No. 17 and TAKUNAN MARU No. 5 and auxiliary netlayer FUKUEI MARU No. 15.

The Invasion Force departs Koniya, Amami Oshima for Lamon Bay, Quezon, Philippines.

24 December 1941:
The Invasion Force arrives at Lamon Bay. The landings proceed without strong opposition.

29 December 1941:
SENKO MARU departs Lamon Bay and arrives in Formosa at an unknown date.

E Early 1942:
Merchant captain Kisaburo Tominaga is appointed commanding officer. He remains for the entire war and resigns in Nov '45.

12 January 1942:
Transfers medical supplies to auxiliary hospital ship ASAHI MARU (ex-Italian DANTE ALIGHIERI).

26 February 1942:
At 0700 departs Davao in a convoy also consisting of oiler NOTORO, auxiliary destroyer tender KAMIKAZE MARU and auxiliary transport HAKONESAN MARUs escorted by minelayer TSUBAME.

28 February 1942:
At 1600, auxiliary transport HAKONESAN MARU detaches.

1 March 1942:
NOTORO transfers a passenger outside the harbor of Tarakan to auxiliary gunboat MANYO MARU. At 0830, arrives at Balikpapan with auxiliary destroyer tender KAMIKAZE MARU and NOTORO escorted by minelayer TSUBAME. At 0918, TSUBAME comes alongside NOTORO and is supplied with coal and water. At 1030, departs in same convoy escorted by TSUBAME.

2 March 1942:
At 1501, off Bandjarmasin, supplies TSUBAME with coal and water. At 1630 arrives at Banjarmasin with oiler AKEBONO MARU.

E 3 March1942:
Off Bandjermasin (now Banjarmasin), SE Borneo, loads weapons and ammunition.

E March 1942:
Attached to the Southwest Area Fleet as an auxiliary transport, (Ko) category. [1]

11 March 1942:
GENYO MARU and KAMIKAZE and SENKO MARUs are reported in the Macassar area being escorted by the minelayer WAKATAKA.

21 March 1942:
Auxiliary gunboat OKUYO MARU transfers four depth-charges (DC) to SENKO MARU.

25 May 1942:
North Macassar Strait. LtCdr (later Rear Admiral) Wreford G. Chapple (USNA ’30) USS PERMIT (SS-178) attacks SENKO MARU and claims a torpedo hit, but no damage is recorded by the Japanese. [2]

1 June 1942:
Departs Macassar, Celebes (now Sulawesi) for Surabaya, Java.

E June 1942:
Arrives at Surabaya.

E June-July 1942:
Departs Surabaya and arrives at Ambon, Moluccas, at unknown dates.

7 July 1942:
Departs Ambon for Macassar, towing auxiliary gunboat TAIKO MARU hit in the engine room and heavily damaged in an RAAF air attack on 13 May. The ships are escorted by auxiliary netlayer NAGARA MARU and auxiliary submarine chaser SHONAN MARU No. 1.

11 July 1942:
Both ships arrive at Macassar.

15 July 1942:
Departs Macassar for Singapore, still towing TAIKO MARU.

21 July 1942:
Both ships arrive at Singapore and enter Keppel harbor.

15 October 1942:
At 1850 departs Macassar escorted by auxiliary gunboat OKUYO MARU and auxiliary submarine chaser SHONAN MARU No. 1.

17 October 1942:
At 0500 between Macassar and Ambon, torpedo boat HATSUKARI and auxuiliary submarine chaser SHONAN MARU No. 2 join the small convoy to provide additional escort.

18 October 1942:
At 1130 arrives at Ambon.

4 February 1943:
At 1700 departs Macassar for Balikpapan.

26 February 1943:
Departs Kendari, Celebes for Ambon with TORA MARU No. 1 escorted by auxiliary gunboat OKUYO MARU and auxiliary submarine chaser SHONAN MARU No. 2 that are met at sea.

27 February 1943:
At 1700 arrives at Ambon.

1 May 1943:
Attached to Combined Fleet, Southwest Area Fleet as an auxiliary transport, (Otsu) category. [1].

25 May 1943:
Departs Kaimana, West Papua for Manokwari, New Guinea.

4 June 1943:
Arrives at Manokwari.

5 September 1943:
Sustains an aerial strafing attack with no damage at Manokwari.

18 October 1943:
At 1000, departs Balikpapan for Palau in convoy No. 2609 also consisting of fleet oiler TSURUMI and KENZAN, DAI (ex-Dutch DUYMAER VAN TWIST) MARUs and OGURA MARU No. 2 (unconfirmed) and three other unidentified ships.

20 October 1943:
At 0800, DAI MARU breaks down and is assisted by auxiliary subchaser CHa-41.

21 October 1943:
At 1000, DAI and KENZAN MARUs and CHa-41 are detached for Menado.

25 October 1943:
The convoy arrives at Palau.

29 October 1943:
At 0600, departs Palau for Balikpapan via Menado, escorted by subchaser CH-4. Later CH-5 is scheduled to take over the escort.

E November 1943:
Arrives at Balikpapan, Borneo.

10 November 1943:
Departs Balikpapan for Padang escorted by minesweeper W-12.

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

15 November 1943:
Runs aground at North Watcher Island, N of west end of Java.

17 November 1943:
Refloated by the 11th Special Construction Unit. South of the Sunda Straits exit, SENKO MARU is torpedoed and hit by an unidentified submarine. [3]

2 December 1943:
SENKO MARU is scheduled to depart Padang for Balikpapan with minesweeper W-8 as escort. On 30 November however, W 8 is recalled to Surabaya.

1 January 1944:
At 0600, SENKO MARU departs Balikpapan for Kupang, Borneo via Macassar.

1 February 1944:
Attached to Second Southern Expeditionary Fleet.

15 February 1944:
Departs Surabaya for Ambon.

20 February 1944:
Arrives at Ambon.

24 February 1944:
Departs Ambon for Macassar escorted by auxiliary subchaser TAKUNAN MARU No. 5.

26 February 1944:
TAKUNAN MARU No. 5 is detached off Wowoni Island.

28 February 1944:
Arrives at Macassar.

2 March 1944:
Departs Macassar for Surabaya.

5 March 1944:
Arrives at Surabaya.

23 March 1944:
At 1500, departs Surabaya for Laut island, S Borneo (now Kalimantan) in a convoy also consisting of IKUTAGAWA MARU (ex-Italian CALITEA II) with patrol boat PB-104 as escort.

24 March 1944:
The convoy arrives at Laut Island to load iron and coal. Then, SENKO MARU departs Laut Island and arrives the same day at Balikpapan, Borneo. Strikes a mine off the harbor.

25 March 1944:
Returns back to Balikpapan for temporary repairs.

13 April 1944:
Departs Balikpapan for Surabaya.

17 April 1944:
Arrives at Surabaya. Enters shipyard for permanent repairs.

31 July 1944:
Repairs are completed, undocked.

8 August 1944:
Departs Surabaya for Jakarta (ex-Batavia, renamed by the Japanese after its capture).

10 August 1944:
Arrives at Jakarta.

15 August 1944:
Departs Jakarta for Batam (Batang) Island, S of Singapore.

24-25 August 1944:
Boengos (Bungus) Bay, S of Padang, W Sumatra. Sustains aerials attacks from British carrier aircraft. SENKO MARU is hit by bombs in hold No. 3 and No. 10, near her engine room. Fires are brought under control by water, but damage is extensive and two Type-96 25mm AA guns, two 13mm and one 7.7mm AA gun are destroyed. Repairs are scheduled to be made at Surabaya shipyard.

23 July 1945:
Bombed in Boengos Bay. Engine room hit. Badly damaged and subsequently beached.

1 September 1945:
Towed to Emma Haven (now Teluk Bayur), Padang.

11 October 1945:
Seized by Indonesian rebels.

3 November 1945:
Bombed and sunk by Dutch aircraft bombing the Indonesian rebels.

3 May 1947:
Removed from the Navy List under internal order No. 327.

Authors Notes:
[1] There were two categories of Zatsuyosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.

[2] No details of this attack are reported by Japanese source.

[3] No such attack is claimed by any Allied submarine.

Thanks go to Gengoro S. Toda of Japan and Berend van der Wal of Netherlands.

-Gilbert Casse, Bob Hackett and Peter Cundall

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