Japanese Transports

ZATSUYOSEN!

((No photo is known to exist of Iwato Maru. The attached photo of Hirota Maru is representative of what the ship may have looked like – Peter Cundall’s Collection)
)

IJN IWATO MARU :
Tabular Record of Movement

© 2015 Gilbert Casse and Peter Cundall

November 1938:
Osaka. Laid down by Nakata Zosensho K.K. shipyard for Kunjiro Okubo as a 526-tons cargo ship.
20 February 1939:
Launched and named IWATO MARU.
18 April 1939:
Completed and registered at Tarumi, Hyogo Prefecture.
1939:
Chartered to Sanko Kisen K.K.
14 June 1940:
Requisitioned by the IJN as a general requisitioned ship.
18 December 1941:
Shimonoseki, Yamaguchi Prefecture. Begins conversion to military duty at Hayashikane Tekko Zosen K.K.
20 December 1941:
Registered in the IJN as an auxiliary netlayer attached to the Sasebo Naval District under instruction No. 1699.
31 December 1941:
Assigned to Vice Admiral Yamamoto Koki‘s (36) Mako Guard District, Base Force, Base Defence Unit under instruction No. 1780.
December 1941:
Departs Mako, Pescadores.
10 January 1942:
The conversion is completed.
15 January 1942:
Assigned to Mako Guard District, Base Force, Base Defence Unit under Mako Guard District instruction No. 41.
18 January 1942:
Departs Sasebo.
22 January 1942:
Arrives in South Straits.
24 January 1942:
Exits South Straits waters.
26 January 1942:
Arrives at Mako.
February 1942:
Undergoes diesel engine repairs at Mako Naval Yard.
18 February 1942:
Departs Mako on patrol duties.
24 February 1942:
Arrives back at Mako.
26 February 1942:
Departs Mako on patrol duties.
28 February 1942:
Arrives back at Mako.
29 March 1942:
Performs her first gunnery drill W of Mako.
July 1942:
Departs Mako.
25 July 1942:
Performs her third gunnery drill W of Mako.
7 ~ 9 September 1942:
Performs her first fleet exercise.
28 September ~ 1 October 1942:
Performs her second fleet exercise.
1 October 1942:
Assigned to Mako Guard District, Base Force, Kirun Defence Unit under Mako Guard District instruction No. 55.
3 October 1942:
Departs Mako and arrives at Kirun, Formosa (now Keelung, Taiwan) later that day.
14 October 1942:
Assigned to ASW sweep under Mako Guard District instruction No. 71.
14 ~ 18 October 1942:
Engages in ASW sweeping and rescue of small ship TEIMURA MARU.
20 October 1942:
Departs Ryojun and arrives at Chinkai later that same day.
11 ~ 13 November 1942:
Performs her first fleet drill.
28 ~ 30 December 1942:
Performs her second fleet drill.
4 ~ 6 February 1943:
Performs her fifth fleet drill.
24 ~ 26 February 1943:
Performs her sixth fleet drill.
1 April 1943:
Assigned to Mako Guard District, Base Force under Mako Guard District instruction No. 588. Assigned to Kirun Defence Unit under Mako Guard District instruction No. 6.
17 April 1943:
Assigned to ASW sweep and rescue mission of IJN requisitioned ship (ex-whale factory ship) (B-AK) NISSHIN MARU No. 2 under Mako Guard District instruction No. 47. [1]
20 April 1943:
Rescue mission of NISSHIN MARU No. 2 is organized by Air Rescue Service under Mako Guard District instruction No. 52. Vessels involved include destroyer SANAE, salvage tugs SHOHO and NANSHIN MARUs and auxiliary patrol boats YOBAI and OYO MARUs and NITTO MARU No. 21.
25 April 1943:
ASW sweep related to NISSHIN MARU No. 2 is ended under Mako Guard District instruction No. 57.
28 April 1943:
Air Rescue Service organization related to NISSHIN MARU No. 2 is ended under Mako Guard District instruction No. 61.
3 ~ 8 May 1943:
Performs her 11th fleet drill.
1 June 1943:
Assigned from 8 Jun ’43 to Mako Guard District, Base Force, Base Defence Unit under Mako Guard District instruction No. 15.
3 ~ 5 June 1943:
Performs her 13th fleet drill.
23 ~ 25 June 1943:
Performs her 14th fleet drill.
8 ~ 10 July 1943:
Performs her 15th fleet drill.
28 ~ 30 July 1943:
Performs her 16th fleet drill.
9 ~ 11 August 1943:
Performs her 17th fleet drill.
16 August 1943:
Assigned to ASW sweep at position 24-55N, 120-50E under Mako Guard District instruction No. 217.
17 August 1943:
At 2350, sights and attacks a surfacing submarine at position 25-16N, 120-10E.
20 August 1943:
Ordered to end current ASW sweep at 1200 under Mako Guard District instruction No. 223. Assigned to another ASW sweep at position 24-27N, 120-23E under Mako Guard District instruction No. 225.
22 August 1943:
Ordered to end current ASW sweep at 0800 under Mako Guard District instruction No. 229.
25 ~ 27 August 1943:
Performs her 18th fleet drill.
9 September 1943:
Assigned to ASW sweep under Mako Guard District instruction No. 262.
12 September 1943:
Ordered to end current ASW sweep at 1200 under Mako Guard District instruction No. 266.
18 September 1943:
Assigned to ASW sweep under Mako Guard District instruction No. 277.
20 September 1943:
Ordered to end current ASW sweep at 1200 under Mako Guard District instruction No. 280.
22 September 1943:
Assigned from 1 Oct ’43 to Mako Guard District, Base Force, Kirun Defence Unit under Mako Guard District instruction No. 21. Assigned to ASW sweep under Mako Guard District instruction No. 285.
23 September 1943:
Ordered to stop current ASW sweep and to return to base under Mako Guard District instruction No. 289.
27 September 1943:
Assigned from 1 Oct ’43 to Mako Guard District, Base Force, Base Defence Unit under Mako Guard District instruction No. 22.
27 ~ 29 September 1943:
Performs her 20th fleet drill.
September 1943:
Her owners are changed to Chugoku Unko K.K. and her port of registry to Tokushima, Shikoku.
28 September 1943:
Scheduled to be converted to an auxiliary transport under Navy’s secret directive No. 4917.
30 September 1943:
Arrives at Daito Wan (Bay).
1 October 1943:
Detached from Mako Naval District, Base Force under instruction No. 2039. Removed from the Navy’s list under instruction No. 2040. Registered that same day in the Navy’s list as an auxiliary transport (Otsu) category attached to the Sasebo Naval District with Sasebo as home port under instruction No. 2041. Lt. Makizaki Togo is appointed CO. [2]
October ~ November 1943:
Undergoes conversion to actual military duty at the Mako Naval Yard.
26 November 1943:
Departs Mako on trials and returns to base later in the day. Departs later.
13 December 1943:
Departs Takao, Formosa (now Kaohsiung, Taiwan).
14 December 1943:
Arrives at Mako.
25 December 1943:
Departs Takao and arrives at Mako later that day.
30 December 1943:
Departs Mako and arrives at Takao.
1944:
Her owners are changed to Nihon Kinkai Kisen K.K and port of registry to Kobe.
3 January 1944:
Departs Takao Naval Base and arrives at Takao commercial port. Loads 100 mines, iron plate, ammunition and other sundries totaling 200-tons.
7 January 1944:
Departs Takao and arrives at Mako later in the day. Loads ammunition.
10 January 1944:
Departs Mako.
11 January 1944:
Arrives at Takao.
E 12 ~ 14 January 1944:
Loads 70-tons of coal, one car, general cargo totaling 200-tons, aviation weapons totaling 30-M3, wood and other sundries totaling 100-tons.
15 January 1944:
Departs Takao commercial port.
16 January 1944:
Arrives at Mako. Loads old ammunition bound for Takao.
26 January 1944:
Departs Mako.
27 January 1944:
Arrives at Takao commercial port.
31 January 1944:
Loads one machine with starter, about 150-tons of equipment, 13-tons of cement and other sundries totaling 60-tons. Departs Takao and arrives at Mako later that day.
E 2 ~ 4 February 1944:
Loads 45-tons of iron plate and ammunition.
4 February 1944:
Departs Mako and arrives at Takao Naval Base later that day. Transfers later that day to commercial port.
E 5 ~ 7 February 1944:
Loads 300-tons of coal, 100-M3 of coke, 20-tons of building materials and aviation weapons totaling 5-M3.
8 February 1944:
Departs Takao commercial port and arrives at Mako later in the day. Loads a generator and ammunition.
12 February 1944:
Departs Mako and arrives at Takao Naval Base. Transfers to commercial port later that same day.
13 February 1944:
Departs Takao commercial port.
14 February 1944:
Arrives at Karenko, Formosa (now Hualien, Taiwan). Loads about 0,60-tons of wood.
18 February 1944:
Departs Hualien.
19 February 1944:
At 1300, arrives at Takao commercial port.
E 20 ~ 24 February 1944:
Loads 100-tons of coal, 100-ton of aluminum and ammunition.
25 February 1944:
Departs Takao commercial port.
26 February 1944:
Arives at Karenko. Loads about 0,85-tons of wood and 65-tons of aluminum.
2 March 1944:
Departs Karenko.
3 March 1944:
Arrives at Takao commercial port.
10 March 1944:
Departs Takao and arrives at Mako later in the day.
16 March 1944:
Departs Mako and arrives at Takao later that same day.
20 March 1944:
Loads 300-M3 of ammunition and 300-tons of coal. Departs Takao and arrives at Mako later that day.
25 March 1944:
Loads general cargo. Departs Mako and arrives at Takao commercial port later that same day.
31 March 1944:
Loads 100-M3 of ammunition and 200-tons of civilian cargo. Departs Takao commercial port.
1 April 1944:
Arrives at Karenko.
4 April 1944:
Loads about 1,20-tons of special wood appropriate for munition boxes and for motorsailer. Departs Karenko.
5 April 1944:
Arrives at Kirun.
7 April 1944:
Loads 450-tons of old ammunition bound for Takao. Departs Kirun.
8 April 1944:
Arrives at Takao commercial port. Departs later for Karenko.
10 April 1944:
At 0630, departs Karenko.
11 April 1944:
At 1200, arrives at Takao.
13 April 1944:
Loads one car, 1,500 empty drums, 16-M3 of building materials, mild steel plate and other sundries totaling 90-tons. Departs Takao commercial port and arrives at Mako later in the day.
15 April 1944:
Assigned to Mako Guard District, Base Force, Base Defence Unit under Mako Guard District instruction No. 16.
17 April 1944:
Loads 1,600 drums of aviation gas. Departs Mako and arrives at Takao commercial port later that day.
20 April 1944:
Loads 550-M3 of old ammunition bound for Sasebo. Departs Takao commercial port and arrives at Kirun. At 1100, departs there in convoy TAMO-17 also consisting of auxiliary transport HIROTA MARU, IJA transports KYOKUZAN and TOKUSHIMA MARUs, IJA shared transports (A/C-AK) KENEI and SUGIYAMA MARUs, civilian ore carrier (C-AC) HIDA MARU, IJN requisitioned cargo ship (B-AK) TOTTORI MARU and sixteen unidentified merchant ships escorted by kaibokan CD-8, old destroyers HASU and ASAGAO, subchaser CH-8 and auxiliary subchaser TAKUNAN MARU No. 3.
E 22 April 1944:
HASU is detached.
26 April 1944:
Arrives at Osaka. Departs later that day.
27 April 1944:
Arrives at Sasebo.
2 May 1944:
Loads 300-M3 of old quartermaster weapons bound for Takao, aviation weapons totaling 150-M3, emergency goods and other sundries totaling 100-M3. Departs Sasebo.
9 May 1944:
Arrives at Takao commercial port. Departs later.
6 June 1944:
Departs Kagoshima, Kyushu in convoy KATA-614 also consisting of auxiliary transport TOYOSAKA MARU, IJA transport UNYO MARU No. 7, IJA shared transports (A/C-AK) SAKISHIMA and DAISHIN MARUs, IJA shared tanker (A/C-AO) NANSHIN MARU No. 18, civilian tanker (C-AO) YAEI MARU No. 5, civilian cargo ships (C-AK) SANYO, TOSHU MARUs and SHINTAI MARU No. 2 and five unidentified merchant ships, escorted by minelayer TSUBAME, minesweeper W-15, auxiliary minesweepers HAKATA MARU No. 6, BANSHU MARU No. 51, TOSHI MARU No. 7 and SHIMPO MARU and auxiliary patrol boat CHOUN MARU No. 13. TOSHU MARU is towing hyoteki HA-58.
7 June 1944:
Arrives at Koniya, Amami-Oshima. SANYO MARU is detached to Naze and TOYOSAKA MARU to Seso.
9 June 1944:
Departs Koniya.
10 June 1944:
Arrives at Naha, Okinawa.
11 June 1944:
Departs Naha.
12 June 1944:
Arrives at Ishigaki, Yaeyama Retto (Islands). Departs later that day.
13 June 1944:
Arrives at Kirun.
15 June 1944:
Departs Kirun.
16 June 1944:
Arrives at Takao.
23 June 1944:
Departs Takao and arrives at Haikow, Hainan Island later in the day.
24 June 1944:
Departs Haikow and arrives at Karenko Harbor later that day.
27 June 1944:
Departs Karenko Harbor and arrives at Kirun later that same day.
1 July 1944:
Departs Kirun.
2 July 1944:
Arrives at Takao.
12 July 1944:
At 1445, departs Takao in convoy MI-06 also consisting of auxiliary oilers JUKO MARU and OGURA MARU No. 2, IJA tankers ATAGO, RIKKO, ZUIHO and TACHIBANA MARUs, UNKAI MARU No. 5 and YAMAMIZU MARU No. 2, civilian tanker (C-AO) TOKUWA MARU and auxiliary transport HIROTA MARU, IJA transports TSUYAMA, AKAGISAN, KANKYO, AOBASAN, GENKAI and YAGI MARUs escorted by kaibokan CD-8 and CD-14, patrol boat P-38, auxiliary patrol boat TAKUNAN MARU No. 3 and minesweeper W-18.
13 July 1944:
At some point, IWATO MARU is detached from the convoy and arrives at Kirun.
22 July 1944:
Departs Kirun.
25 July 1944:
Arrives at Shanghai.
6 August 1944:
Departs Shanghai.
9 August 1944:
Arrives at Kirun.
18 August 1944:
Departs Kirun.
19 August 1944:
Arrives at Takao Naval Base.
22 August 1944:
Transfers to Takao commercial port.
27 August 1944:
Departs Takao commercial port.
28 August 1944:
Arrives at Batan Island, N of Luzon Philippines.
31 August 1944:
Departs Batan.
2 September 1944:
Arrives at Takao commercial port.
6 September 1944:
Departs Takao commercial port and arrives at Mako later that day.
20 September 1944:
Departs Mako and arrives at Takao commercial port later that same day.
5 October 1944:
Departs Takao commercial port and arrives at Mako later that day.
12 October 1944:
Engages in surface to air combat.
21 October 1944:
Departs Mako and arrives at Takao commercial port later that same day.
20 November 1944:
Departs Takao commercial port and arrives at Boryo (Horyu), Formosa later that day.
22 November 1944:
Departs Boryo and arrives at Daitaha later that same day.
23 November 1944:
Departs Daitaha and arrives at Haikow later that day.
24 November 1944:
Departs Haikow and arrives at Takao later in the day.
4 January 1945:
TF 38 continues operations against Japanese airfields and shipping in the Formosa area. IWATO MARU is bombed and sunk NE of Formosa by TF 38 aircraft with the loss of seven crewmen.
10 March 1945:
Removed from the Navy’s list under instruction No. 232.

Authors notes :
[1] NISSHIN MARU No. 2 was torpedoed and damaged with the loss of 12 crewmen and 14 gunners, probably by LtCdr (later Cdr) Royce L. Gross’ (USNA ’30) USS SEAWOLF (SS-107. The agent of NISSHIN MARU No. 2’s destruction is unknown. The mid-body eventually drifted ashore on Formosa and was scrapped locally.
[2] There were two categories of Zatsuyosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.
Thanks go to Gengoro S. Toda of Japan. Thanks also go to Jeff Donahoo of Iowa for Officers’ info.

Gilbert Casse and Peter Cundall.

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