(Rio de Janeiro Maru as a pre-war O.S.K. liner)
IJN Submarine Tender
RIO DE JANEIRO MARU: Tabular Record of Movement
© 1998-2015 Bob Hackett, Sander Kingsepp and Peter Cundall.
16 May 1929:
Nagasaki. Laid down at Mitsubishi Shipbuilding as a 9,627 GRT passenger-cargo liner for the Osaka Shosen Kaisha (OSK) Line.
19 November 1929:
Launched and named RIO DE JANEIRO MARU.
15 May 1930:
Completed. RIO DE JANEIRO MARU can accomodate 1,140 passengers.
1 June 1930:
Departs her home port of Kobe on her maiden voyage to OSK's South American ports of call.
7 January 1931:
Arrives at Santos, Brazil on No. 156 Emigrant Voyage. 
3 July 1931:
Arrives at Santos, Brazil on No. 165 Emigrant Voyage.
16 December 1931:
Arrives at Santos, Brazil on No. 171 Emigrant Voyage.
2 June 1932:
Arrives Santos on No. 177 Emigrant Voyage.
7 November 1932:
Arrives at Santos, Brazil on No. 184 Emigrant Voyage.
16 April 1933:
Arrives at Santos, Brazil on No. 194 Emigrant Voyage.
2 October 1933:
Arrives at Santos, Brazil on No. 205 Emigrant Voyage.
4 March 1934:
Arrives Santos on No. 215 Emigrant Voyage.
Runs aground in the Mississippi River estuary.
1 August 1934:
Arrives at Santos, Brazil on No. 225 Emigrant Voyage.
1 January 1935:
Arrives Santos on No. 235 Emigrant Voyage.
31 May 1935:
Arrives at Santos, Brazil on No. 244 Emigrant Voyage.
30 October 1935:
Arrives at Santos, Brazil on No. 251 Emigrant Voyage.
29 August 1936:
Arrives at Santos, Brazil on No. 260 Emigrant Voyage.
Provides around-the-world service. Ports of call include Yokohama, Hong Kong, Singapore, Colombo, Durban, Cape Town, Rio de Janeiro, Santos, Montevideo, Buenos Aires, Belem, Cristobal, Balboa and Los Angeles.
30 May 1937:
Arrives at Santos, Brazil on No. 271 Emigrant Voyage.
13 November 1937:
Arrives Santos on No. 275 Emigrant Voyage.
16 March 1938:
Arrives at Santos, Brazil on No. 278 Emigrant Voyage.
1 August 1938:
Arrives at Santos, Brazil on No. 282 Emigrant Voyage.
13 December 1938:
Arrives at Santos, Brazil on No. 285 Emigrant Voyage.
17 March 1939:
Departs Kobe on No. 289 Emigrant Voyage.
18 March 1939:
21 March 1939:
23 March 1939:
28 March 1939:
Departs Hong Kong.
3 April 1939:
9 April 1939:
20 April 1939:
24 April 1939:
Departs Cape Town.
5 May 1939:
Departs Rio de Janeiro.
7 May 1939:
10 May 1939:
11 May 1939:
Arrives at Buenos Aires. Then reverse on return voyage.
Makes voyage to eastern coast of South America.
25 August 1939:
Departs Kobe on No. 293 Emigrant Voyage. Sails to Kobe then Los Angeles.
4 September 1939:
Collides with KAGU MARU at 46-16N, 177-10E. RIO DE JANEIRO MARU is damaged and KAGU MARU tows the ship.
22 September 1939:
Salvage tug SEIHA MARU subsequently takes over the tow and tows the ship to Mitsubishi Jukogyo’s Kobe yard where the ship is repaired.
11 May 1940:
Departs Dairen, Manchuria.
22 May 1940:
2 June 1940:
8 October 1940:
Requisitioned by the IJN.
19 October 1940:
Kure Navy Yard. Begins conversion to an auxiliary transport.
1 November 1940:
Registered as an auxiliary transport ship in the Sasebo Naval District. The IJN simply calls her RIO MARU.
30 November 1940:
Completes conversion that includes installation of two 25-mm Type 96 dual AA guns, signal equipment and new accommodation spaces.
24 February 1941:
Departs Sasebo for the South China coast.
3 March 1941:
Arrives at Keelung, Formosa.
25 March 1941:
Registered as a prospective submarine tender in the Sasebo Naval District. Captain Murase Raiji (38) (former CO of MATSUKAZE) is appointed CO.
Banshu, Hyogo. Begins conversion at Harima's shipyard. Four 5.9-inch (150-mm) guns, a range finder and an anti-magnetic mine degaussing coil are fitted. A torpedo and depth charge hangar is constructed as are replenishment goods storage and a medical facility. Motor launch loading equipment is also installed.
7 May 1941:
24 November 1941:
Sasebo. RIO MARU is a tender in Rear Admiral (later Vice Admiral), the Marquis, Daigo Tadashige's (40) (former CO of KINU) SubRon 5 with light cruiser YURA (F), SubDiv 28 (I-59, I-60), SubDiv 29 (I-62, I-64) and SubDiv 30 (I-65, I-66).
Departs Sasebo for Palau with the YURA and SubDivs 29 and 30. Enroute, SubRon 5 is diverted to Samah, Hainan Island, China.
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).
8 December 1941: Operation "E"- The Invasion of Malaya:
RIO MARU arrives at Camranh Bay, Indochina. That same day, Japanese forces land on the Kra Isthmus of Thailand and NE Malaya.
Kure. Seven coils are fitted all around the ship's side for magnetic mine degaussing.
8 January 1942:
Departs Camranh Bay.
10 January 1942:
Arrives at Singora, Malaya and disembarks personnel and equipment of the 11th Submarine Base Unit. Later, steams to Kota Bharu, Malaya, then Brunei, Borneo.
7 March 1942:
Arrives at Penang.
22 March 1942:
2 April 1942:
Arrives at Sasebo.
10 April 1942:
Sasebo. RIO MARU is in SubRon 5 with SubDiv 19 (I-56, I-57, I-58), SubDiv 28 (I-59, I-62) and SubDiv 30 (I-64, I-65, I-66).
28 April 1942:
Departs Sasebo for Kure.
5 May 1942:
Departs Kure for Sasebo.
7 May 1942:
Captain-Retired (later Rear Admiral) Ohashi Tatsuo (40) (former CO of RO-68) assumes command.
14 May 1942: Operation “MI” - The Battle of Midway:
RIO MARU is assigned to Vice Admiral, the Marquis, Komatsu Teruhisa’s (37) (former CO of NACHI) Advance (Submarine) Force’s (Sixth Fleet). She is designated flagship and tender of Rear Admiral (later Vice Admiral) Kawano Chimaki’s SubRon 3 consisting of SubDivs 13, 19 and 30 based at Kwajalein.
24 May 1942:
Arrives at Kwajalein.
29 May 1942:
Balabac Strait, N of Borneo. LtCdr (later Rear Admiral) Chester C. Smith's (USNA ’25) USS SWORDFISH (SS-193) operating from Fremantle, Australia, is patrolling the Strait. Smith’s lookouts spot a small convoy and he sets up for a submerged night attack. Smith fires two Mark 14 steam torpedoes at what he identifies at a “5,000-ton” oiler,
but claims no hits.
Actually, one of his torpedoes hits RIO MARU and rips open a 46-foot long by 26-foot wide hole in Hold No. 1. Smith then attacks another ship in the convoy and fires two torpedoes at it. He hits and sinks IJA transport TATSUFUKU MARU with the loss of 12 crewmen and 36 troops.
Six sailors volunteer to enter RIO MARU's flooded compartment and seal the leak. Later, they receive a commendation from the CINC, Combined Fleet, Admiral (Fleet Admiral posthumously) Yamamoto Isoroku (32) (former CO of AKAGI). Repair ships KASUGA MARU and YAMABIKO MARU arrive later and tow RIO MARU to Singapore for repairs. 
Singapore. RIO MARU is drydocked and repaired at Seletar's No. 1 Shipyard (former King George V Graving Dock).
1 July 1942:
Surabaya. Provisioned by auxiliary storeship HAKUREI MARU.
2 July 1942:
Arrives at Sasebo.
10 July 1942:
SubRon 5 is disbanded.
14 July 1942:
Reassigned to Vice Admiral Takahashi Ibo's (36) (former Co of KIRISHIMA) Southwest Area Fleet as a tender for flagship I-8 and SubDiv 30 (I-162, I-163, I-166).
21 July 1942:
27 July 1942:
94 miles E of Camranh, Indochina. RIO MARU is attacked by LtCdr (later Rear Admiral) James C. Dempsey's (USNA ’31) (former CO of USS S-37) USS SPEARFISH (SS-190). Dempsey later claims two hits of four torpedoes he fires in a submerged night attack. He departs thinking the stopped ship is sinking by the stern. The next day, Captain Ohashi reports RIO MARU suffered "medium" damage, but is able to proceed to Hong Kong for repairs.
3 August 1942:
Arrives at Camranh Bay.
27 August 1942:
Replenishes SubDiv 30 and departs Camranh Bay later that day. Proceeds to Singapore with repair ship YAMABIKO MARU and undergoes more permanent repairs.
6 October 1942:
Attached to SubRon 5 with SubDiv 19.
1 January 1943:
Surabaya, Java. Continues service as a tender in the Southwest Area Fleet's SubDiv 30 (1-162, 1-165, 1-166).
25 January 1943:
Employed in transporting air field construction materials to Kokas on the Bay of Sekar, W Java.
12 February 1943:
Ambon, Moluccas. Attacked unsuccessfully by aircraft.
16 March 1943:
Assigned to the Second Southern Expeditionary Fleet of the Southwest Area Fleet.
1 May 1943:
Departs Java for Ambon carrying 200 Allied POWs.
1 July 1943:
At Surabaya provisioned by auxiliary storeship HAKUREI MARU.
2 July 1943:
Loads drums and cargo for Balikpapan, Borneo. RIO MARU is scheduled to carry 5,000 drums of AvGas to Yokosuka.
16 July 1943:
23 July 1943:
At Sorong, Vogelkop Peninsula, New Guinea.
24 July 1943:
Minelayer WAKATAKA escorts RIO MARU through Dampier Strait as far as the easternmost tip of Waigeo Island.
27 July 1943:
Arrives at Balikpapan.
1 August 1943:
3 August 1943:
Arrives at Surabaya.
23 August 1943:
Arrives at Ambon.
29 August 1943:
Arrives at Surabaya, Java.
30 August 1943:
31 August 1943:
Arrives at Tarakan.
3 September 1943:
Arrives at Davao, Philippines.
15 September 1943:
Arrives at Manila.
That same day, Captain Ohashi is designated the Supervisor of Modification. RIO MARU is rerated an auxiliary transport in the Sasebo Naval District.
Departs Manila for Balikpapan.
2 October 1943:
Departs Macassar, Celebes for Batavia (Jakarta), Java carrying 200 Allied POWs.
4 October 1943:
Arrives at Batavia.
11 October 1943:
Departs Surabaya escorted by minesweeper W-8 until following day.
22 October 1943:
At 0900, departs Surabaya at 11 knots with oiler KAMOI escorted by minesweeper W-8 as far as the Banka Straits.
25 October 1943:
At 1600, arrives off Horsburgh Light near Singapore.
31 October 1943:
Departs Singapore for Cap St. Jacques, Indochina.
2 November 1943:
Arrives at Cap St. Jacques.
10 November 1943:
Arrives at Takao, Formosa in convoy with NICHIRAN MARU.
14 November 1943:
18 November 1943:
Arrives at Sasebo.
24 November 1943:
26 November 1943:
Arrives at Kure.
29 November 1943:
30 November 1943:
Arrives at Osaka.
5 December 1943:
Recalled Captain-Retired Kanemasu Yoshio (40) (former CO of OI) is posted as Supervisor of Modification. Captain Ohashi is reassigned to the Kure Naval District.
14 December 1943:
Departs Osaka. Arrives at the Aioi Shipyard. Begins modifications of a unknown nature, possibly installation of Type 96 25mm AA machine guns and search radar as carried out at Aioi on other sub tenders.
13 January 1944:
Departs Aioi at 0700 for Miike. Captain Kanemasu is the CO. Completes modifications.
18 January 1944:
Arrives at Kure Naval Arsenal. Loads thousands of rounds of various sizes of ammunition destined for light cruiser AGANO that is undergoing repairs at Truk by repair ship AKASHI.
23 January 1944:
Departs Kure. Arrives at Kobe.
27 January 1944:
29 January 1944:
Arrives at Yokosuka. Loads a cargo of depth charges, coastal defense guns, foodstuffs and mail for transport.
3 February 1944:
Departs Yokosuka escorted by YUZUKI.
11 February 1944:
Arrives at Truk.
17 February 1944: American Operation "Hailstone" - The Attack on Truk:
Vice Admiral (later Admiral) Marc A. Mitscher’s (USNA ’10) Task Force 58's five fleet carriers and four light carriers, supported by six battleships, ten cruisers and 28 destroyers, launch air attacks on airfields, shore installations and ships in the lagoon. Mitscher launches 30 strikes of at least 150 aircraft each. Beginning at dawn, the strikes are launched about every hour for two days.
East of Uman Island. Anchored RIO DE JANEIRO MARU is hit by 1,000-lb. bombs during TF 58's first attacks, probably dropped by SBDs of USS YORKTOWN (CV-10) and SB2Cs of USS BUNKER HILL (CV-17). Captain Kanemasu is KIA. He is promoted Rear Admiral, posthumously.
18 February 1944:
At 0030, RIO DE JANEIRO MARU sinks with the loss of two crewmen. She comes to rest on her starboard side at depth of 115 feet.
Task Force 58 sinks 31 transports and 10 naval vessels (two cruisers, four destroyers and four auxiliary vessels), destroys nearly 200 aircraft and damages severely about 100 more. Truk is eliminated as a major fleet anchorage for the IJN.
31 March 1944:
Removed from the Navy List.
 Three quarters of all Japanese prewar immigrants to Brazil arrived between 1925 and 1935, when Japan was preparing for its military and territorial expansion in East Asia. In 1933, immigrants from Japan numbered 24,494
or 53.2 percent of all immigrants entering Brazil that year. Most hoped to return home when they had made enough money as plantation workers to start over in Japan. Often, they were not paid the agreed upon wages and living and working conditions were far worse than expected. They were forced to buy their food and other supplies at exorbitant prices at stores owned by plantation owners. In the late 1930s, the number of Japanese immigrants to Brazil sharply declined as Japanese emigration headed to Manchuria, China, and Korea.
 Many books and Orders of Battle (OOB) erroneously list RIO DE JANEIRO MARU as being at Kwajalein during the Battle of Midway.
 Because of the conditions Allied POWs had to endure aboard her, RIO DE JANEIRO MARU was considered a "Hell Ship."
Thanks go to Toda Gengoro of Japan for information in Revision 2. Thanks also go to Gilbert Casse of France.
- Bob Hackett, Sander Kingsepp and Peter Cundall.
to Submarine Tender Page