(IRO in warime camoflague scheme)
Tabular Record of Movement
© 2006-2015 Bob Hackett and Peter Cundall.
2 September 1921:
Osaka. Laid down at Osaka Iron Work's Sakurajima factory.
5 August 1922:
Launched and named IRO.
30 October 1922:
Osaka. Completed and registered in the Kure Naval District.
1 July 1924:
Cdr (later Rear Admiral) Tomioka Aijiro (32) assumes acting command.
10 November 1924:
Cdr (later Rear Admiral) Mihori Denzo (32)(former CO of NOJIMA) is appointed Commanding Officer.
1 December 1924:
Cdr Mihori is promoted Captain.
10 July 1925:
Captain Mihori assumes "paper" command of survey ship YAMATO as an additional duty.
18 September 1925:
A new, but unknown captain assumes command.
15 October 1926:
Cdr (later Rear Admiral) Tachibana Hajime (33) is appointed CO.
1 December 1926:
Cdr Tachibana is promoted Captain.
1 April 1927:
Captain (later Rear Admiral) Sezaki Nihei (32), CO of SETTSU, assumes "paper" command of IRO.
1 May 1927:
A new, but unknown captain assumes command.
21 February 1938:
Captain (Rear Admiral, posthumously) Sugimoto Michio (41)(CO of TOKIWA, assumes "paper" command of IRO.
15 April 1938:
Captain (later Rear Admiral) Ishizaki Noboru (42)(former CO of SATA) is appointed CO.
15 December 1938:
Captain (later Rear Admiral) Asakura Bunji (44) is appointed CO. Captain Ishizaki is reassigned as the Chief Instructor of the Submarine School.
1 September 1939:
Captain (later Rear Admiral) Horie Giichiro (43)(former XO of YAKUMO) is appointed CO. Captain Asakura is reassigned as an instructor at the Naval Academy.
15 November 1939:
Captain (later Rear Admiral) Nishina Kozo (44) is appointed CO. Captain Horie is reassigned as CO of KAKO.
10 March 1940:
Captain (later Rear Admiral) Takahashi Yuji (44) assumes command. Captain Nishina is reassigned to the Naval Shipbuilding Command.
15 October 1940:
Captain (Vice Admiral, posthumously) Inoguchi, Toshihira (46) is appointed CO. Captain Takahashi is reassigned as CO of TENRYU.
24 May 1941:
A new, but unknown Captain assumes command. Captain Inoguchi is reassigned as the Chief Instructor at the Gunnery School. In Oct '44, he is KIA as CO of MUSASHI.
1 September 1941:
Cdr (Rear Admiral, posthumously) Matsuda Takatomo (45) (former XO of NAKA) is appointed CO.
31 October 1941:
IRO is assigned to the 4th Fleet.
20 November 1941:
2 December 1941: Operation "Z":
The coded signal "Niitakayama nobore (Climb Mt. Niitaka) 1208" is received from the Combined Fleet. It signifies that hostilities will commence on 8 December (Japan time).
4 December 1941:
8 December 1941: The Invasion of Wake Island:
IRO departs Kwajalein to support the operations against Wake Island.
Rear Admiral (Vice Admiral, posthumously) Kajioka Sadamichi's (39) (former CO of KISO) Wake Island Attack Force departs Roi-Namur, Kwajalein with CruDiv 18's TATSUTA and TENRYU, DesRon 6's light cruiser YUBARI, DesDiv 29's OITE and HAYATE, DesDiv 30's KISARAGI, MUTSUKI, YAYOI and MOCHIZUKI, two converted destroyer transports, submarine depot ship JINGEI and transports KONGO and KINRYU MARUs.
11 December 1941:
YUBARI and three destroyers close to within 4,500 yards of Wake Island to bombard American positions. At 0615, Marine 1st Lt Clarence A. Barninger's Battery "A" 5-inch guns open fire. YUBARI is straddled, but not hit. She opens the range to 5,700 yards, and is straddled twice more, but not hit.
Two miles SW of Wake Island. HAYATE, OITE and ASANAGI close to bombard Wilkes Island. HAYATE takes three direct hits from salvos of Marine 2nd Lt John A. McAlister's Battery "L" 5-inch guns. At 0652, HAYATE blows up and sinks with her entire crew of 168 at 19-16 N, 166-37 E. Battery "L" also scores a near-miss that damages OITE. DesDiv 30's YAYOI, MUTSUKI and KISARAGI close to bombard both Wilkes and Peale Islands. 1st Lt Woodrow W. Kessler's Battery "B" 5-inch guns on Peale open fire and score a hit on YAYOI.
30 miles SW of Wake. At 0724, USMC Grumman F4F "Wildcats" strafe TENRYU and damage three torpedoes on her deck. A Wildcat strafes TATSUTA and hits her radio shack with machine-gun fire.
Captain Henry T. Elrod, USMC, hits KISARAGI with a 100-lb. bomb that probably detonates her depth charges. At 0731, she blows up and sinks with her entire crew of 150 at 18-55 N, 166-17 E.
That morning, a dejected Rear Admiral Kajioka orders his Attack Force to return to Kwajalein.
13 December 1941:
Arrives at Roi, Kwajalein.
18 December 1941:
28 December 1941:
Arrives at Yokosuka.
5 January 1942:
14 January 1942:
Arrives at Truk.
17 January 1942:
23 January 1942: Operation "O"- The Invasion of Rabaul and Kavieng:
Provides refueling support for the invasion landings.
24 January 1942:
Refuels cruiser AOBA at sea.
28 January 1942:
Arrives at Rabaul.
4 February 1942:
17 February 1942:
Arrives at Yokosuka.
24 February 1942:
11 March 1942:
Arrives at Rabaul.
15 March 1942:
29 March 1942:
Arrives at Yokosuka.
9 April 1942:
28 April 1942:
Arrives at Rabaul, New Britain. Engages in replenishment of fleet units.
30 April 1942: Operation “MO” – The Invasions of Tulagi and Port Moresby:
Rabaul. Rear Admiral Kajioka's Port Moresby Attack Force departs 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 (40) (former CO of HIEI) Transport Force of five Navy and six Army transports, oilers IRO (at anchor at Shortland) and GOYO and HOYO MARUs, repair ship OJIMA, escorted by mine-sweepers W-20, HAGOROMO MARU, NOSHIRO MARU No. 2, FUMI MARU No. 2 and mine layer TSUGARU towards the Jomard Pass in the Louisiade Archipelago.
The Attack Force stops briefly at Shortland Islands, Bougainville to setup a seaplane base. IRO remains at Shortlands as a Station Tanker with KEIJO MARU and elements of the 84th Guard Unit.
4 May 1942:
Cdr Matsuda is promoted to Captain.
5 May 1942:
Shortland Islands Anchorage, Bougainville. CruDiv 6's KINUGASA, AOBA, FURUTAKA and KAKO arrive and refuel from IRO.
9 May 1942: The Battle of Coral Sea.
After the Battle of Coral Sea, Operation MO is canceled and the Attack Force returns to Rabaul.
13 May 1942:
30 May 1942:
Arrives at Kure. Dry docked for repairs.
23 June 1942:
Undocked. Departs Kure.
11 July 1942:
Arrives at Rabaul. Engages in oil transport runs between Rabaul and Truk.
22 August 1942:
A new, but unknown, Captain assumes command. Captain Matsuda is reassigned to the Yokosuka Naval District. In Feb '44, he is KIA as CO of light cruiser AGANO.
A new, but unknown, captain assumes command.
4 November 1942:
At 9-00N 155-00E IRO meets up with auxiliary cruiser UKISHIMA MARU which escorts the ship to Truk.
5 November 1942:
Arrives at Truk.
10 November 1942:
Departs Truk with tanker NOTORO escorted by destroyer YUZUKI. At 10 Ri outside the atoll YUZUKI detaches and returns to Truk.
25 December 1942:
Joined by subchaser CH-36 at 31-28N 132-38E and escorted to Fukajima.
26 December 1942:
Arrives at Kure.
14 January 1943:
15 January 1943:
Off Saki. Joined by subchaser CH-36 and escorted south.
E 16 January 1943:
CH-36 is detached at a point 90 degrees off Toi Misaki.
1 February 1943:
At 7-22N 148-53E destroyer YUNAGI meets up with IRO and escorts the tanker to Truk.
2 February 1943:
Arrives at Truk.
15 February 1943:
20 February 1943:
Arrives at Jaluit.
27 February 1943:
Departs Jaluit. At about 0900, W of Jaluit, IRO is torpedoed by LtCdr Raymond H. Bass' (USNA ’31) USS PLUNGER (SS-179). Hit by one of five torpedoes Bass fires, IRO becomes unnavigable. KATORI MARU tows her to Jaluit with SHONAN MARU No. 11 as escort.
4 March 1943:
Arrives at Jaluit. Undergoes repairs for the next two months.
22 April 1943:
Minelayer TOKIWA and IRO depart Kwajalein at 0558 but both return at 1625.
24 April 1943:
TOKIWA and IRO again depart Kwajalein at 0550 and return at 1337.
27 April 1943:
Captain Kitamura Fumio (47) is appointed CO.
21 May 1943:
At 0630 departs Kwajalein under tow by passenger-cargo ship OKITSU MARU escorted by the destroyer OITE, submarine chaser CH-31 and auxiliary sub-chaser TAMA MARU No. 5.
23 May 1943:
Departs Jaluit under tow by passenger-cargo OKITSU MARU escorted by destroyer OITE and subchaser CH-31.
E 30 May 1943:
The convoy arrives at Saipan, Marianas.
1 June 1943:
At 0600 departs Saipan escorted by auxiliary netlayer SHUKO MARU that returns to Saipan the following day, and destroyer OITE.
10 June 1943:
SE of Fuka Island, Oita Ken. At about 0500, IRO, still under tow, is hit by two of four torpedoes fired by LtCdr (later Rear Admiral) Lawrence R. Daspit's' (USNA ’27) USS TINOSA (SS-283) at 31-14N, 132-44E. IRO sustains some flooding , but continues under tow.
Auxiliary minesweepers TAKUNAN MARU No. 3 and TAKUNAN MARU No. 8 join as additional escorts at 31-52N, 132-25E.
12 June 1943:
Arrives at Kure. The tow of some 4,600 miles had been completed at an average speed of 5-6 knots through treacherous waters. The crew of OKITSU MARU receives deservedly profuse congratulations.
30 November 1943:
Dry docked. While undergoing repairs, an experimental camouflage is painted on replacing the dazzle camouflage previously adopted. The new camouflage consists of dark grey overall, except for bow and stern that are painted light grey to give the impression of a smaller, faster oiler with raked bow and cruiser stern. The camouflage is deemed successful, but is not duplicated elsewhere.
8 December 1943:
Departs Saeki for Palau in convoy O-803 consisting of IRO and cargo ships FUKKO and TAIAN MARUs escorted by torpedo boat HATO and minelayer YURISHIMA. TAIAN MARU is towing a crane platform.
10 December 1943:
At 1000, YURISHIMA is detached from the convoy.
18 December 1943:
Arrives at Palau. Loads 8,000-tons of crude oil.
23 December 1943:
Departs Palau in convoy 2516 also consisting of tankers NIPPON and KENYO MARUs escorted by destroyers HAYANAMI and WAKATAKE.
25 December 1943:
At dawn, HAYANAMI is detached.
28 December 1943:
Arrives at Tarakan.
2 January 1944:
At 1600, IRO departs Tarakan with a cargo of refined oil and cargo ship TOSHO MARU, escorted by destroyer WAKATAKE.
4 January 1944:
At 1900, arrives at Balikpapan. Loads a cargo of crude oil.
21 January 1944:
At 0945, IRO departs Balikpapan in convoy O-103 consisting of oilers SATA and JAMBI MARU escorted by patrol boat PB-36 and subchasers CH-37 and CH-41.
23 January 1944:
JAMBI MARU is detached from the convoy and steams to Tarakan.
28 January 1944:
At 1350, arrives at Palau.
19 February 1944:
Palau. Provisioned by auxiliary storeship KITAKAMI MARU.
9 March 1944:
Departs Palau in a convoy with oiler OSE (ex-Dutch GENOTA) escorted by CruDiv 5's MYOKO and HAGURO and destroyer SHIRATSUYU. 
12 March 1944:
Arrives at Balikpapan.
15 March 1944:
At 0730, departs Balikpapan for Palau in convoy O-507 consisting of three echelons of seven ships escorted by destroyers HARUSAME and SHIRATSUYU, patrol boat PB-36, subchaser CH-6 and auxiliary subchaser CHa-52.
The first echelon consists of IRO and passenger-cargo NAGISAN MARU and oiler HISHI MARU No. 2. The second echelon consists of oilers TSURUMI and KYOEI MARU and cargo ship RAIZAN MARU and the third echelon consists only of cargo ship HOKUTAI MARU.
16 March 1944:
At 1530, destroyer MICHISHIO joins the convoy and the other escorts, except for PB-36 escorting IRO, depart.
20 March 1944:
At 0910, auxiliary subchasers CHa-51 and CHa-53 join the escort.
22 March 1944:
LtCdr (later Cdr) John A. Scott's (USNA ’28) USS TUNNY (SS-282) SJ radar picks up a large convoy. At daybreak, Scott is maneuvering to gain an attack position when his radar picks up a destroyer at 14,000 yards. The destroyer sights the submarine and challenges USS TUNNY with a blinker. Scott ducks into a nearby rain squall and continues to close on the surface in conditions of poor visibility. Through the haze, he makes out a group of oilers and cargo ships.
Scott sets up and fires a full bow spread of six-torpedoes at two cargo ships at 07-22N, 132-08E. He and his crew see and hear hits on both, but suddenly, a small oiler, probably KYOEI MARU, appears out of the gloom and almost collides with USS TUNNY.
Scott sets up on destroyer MICHISHIO moving at high speed across USS TUNNY’s stern. He fires four Mark-18 electric torpedoes, then crash dives as depth charges from a trawler explode on his port quarter. During the next four hours, IRO is hit in the bow, forward of the bulkheads. The Japanese drop 87 depth charges on USS TUNNY, but without effect.
23 March 1944:
At 1800 IRO limps into Palau.
30 March 1944: American Operation “Desecrate One”:
Palau. The anchorage is attacked by F6F "Hellcats", SBD "Dauntless", TBF "Avenger" and SB2C "Helldivers" of Task Group 58. 1's USS ENTERPRISE (CV-6), USS BELLEAU WOOD (CVL-24) and USS COWPENS (CVL-25), TG 58. 2's USS BUNKER HILL (CV-17), USS HORNET (CV-12), USS MONTEREY (CV-26) and USS CABOT (CVL-28) and TG 58. 3's USS YORKTOWN (CV-10), USS LEXINGTON (CV-16), USS PRINCETON (CVL-23) and USS LANGLEY (CVL-27).
31 March 1944:
Palau Harbor. TF 58's planes find and attack IRO anchored in a sheltered lagoon close to Koror, Peleliu. She sustains a direct bomb hit in the engine-room and is set afire. Of 250 soldiers on board, 200 survive, but Captain Kitamura is KIA. He is promoted Rear Admiral, posthumously.
17 April 1944:
IRO burns for days. On this day, she sinks in 130 feet of water. Her funnel lies horizontally where it falls across the deck.
10 May 1944:
Removed from the Navy List.
 See TROMS of AIKOKU and HOKOKU MARUs at Tokusetsu Junyokan!
Photo credit goes to Matthew Jones. Grateful thanks to Mr. Gilbert Casse and John Whitman for additional assistance.
- Bob Hackett and Peter Cundall.
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