Midget Submarines at Chichi-jima, Ogasawara (Bonin)
© 2011 Bob Hackett, Sander Kingsepp and Erich Muehlthaler
Ogasawara (Bonin) Islands in the Pacific
15 June 1853:
The Ogasawara Islands lie about 1000 km S of Tokyo and
about 1400 km E of Okinawa. Commodore Matthew C. Perry's side-wheel steamer USS
SUSQUEHANNA (F) and sloop-of-war USS SARATOGA visit the islands as part of
Perry’s tour to open Japanese ports to trade. Perry claims the islands for the
United States to use as a steamship coaling station. Later, the claim is
disavowed by the American Government. 
The Japanese Government sends KANRIN MARU to explore the island
group. Ogasawara Gunto is officially adopted as the name for the complex of
islands consisting of the Chichi-jima, Muko-jima and Haha-jima island groups.
Chichi-jima (Father Island), formerly known in the 19th century to the English
as part of the Bonin Islands, is the largest island in the Ogasawara
archipelago. Chichi-jima is approximately 150 miles (241.4 km) north of Iwo
Japan sends a warship to Ogasawara Gunto and claims them for
the Japanese Empire.
American planners consider Chichi-jima a potential target for
an amphibious landing, but because its mountainous terrain would not permit
rapid construction of airfields, the island is dropped in favor of Iwo Jima.
Photo-recon also shows Chichi-jima more heavily fortified than Iwo.
Six Hei Gata (Type C) midget submarines (HA-62, HA-65, HA-66, HA-71, HA-73 and HA-75) are deployed from Yokosuka to Chichi-jima in two groups. Lt Shinokura Osamu (69), CO of the Chichi-jima detachment, and his service crew chief fly to the island by plane.
23 August 1944:
The 1st group departs Yokosuka for Chichi-jima in a convoy, probably designated No. 3823A, consisting of HA-62 towed by 926 grt converted auxiliary CHOKI MARU, HA-65 by 703grt auxiliary FUJI MARU and HA-73 by 531 grt auxiliary KIRI MARU No. 1 Go. En route, the convoy encounters a typhoon. HA-65 and HA-73 are washed away and lost.
At 1400, the 2nd group departs Yokosuka for Chichi-jima in convoy No. 3823B consisting of HA-66 towed by 479 grt NAGATA MARU, HA-71 by 315 grt HAKUGIN MARU and HA-75 by 376 grt FUYO MARU escorted by subchaser CH-51, auxilary minesweepers Wa-11 and Wa-14. The convoy's planned arrival at Chichi-jima is 1930, 27 Aug '44, but soon after departure encounters the same typhoon. FUYO MARU later
turns back to Tateyama with HA-75.
29 August 1944:
HA-62 arrives at Chichi Jima.
30 August 1944:
At 0530, HAKUGIN MARU and HA-71 arrive at Hachijo-Jima. At 2200, NAGATA MARU and HA-66 arrive at Chichi-jima.
18 September 1944:
A second attempt is made to deliver HA-75. She departs in tow by kaibokan ISOJIMA (ex-Chinese light cruiser NING HAI), probably escorted auxiliary subchaser CHa-170.
19 September 1944:
85 nms from Hachijo-jima. At about 0553, LtCdr Lawrence V. Julihn’s (USNA '37) USS SHAD (SS-235) fires four Mark-23 steam torpedoes and gets three hits on ISOJIMA. While assisting ISOJIMA, CHa-170 requests help, but ISOJIMA sinks at 33-40N, 138-20E. Somehow HA-75 breaks free and begins to drift.
That same day, minesweeper HAGOROMO MARU is escorting SEIAN MARU from Kaminato, Hachiijo-Jima when the minesweeper receives Tokyo Bay Force Secret Radio Message No. 190743. It informs her of the sinking of ISOJIMA and orders her to find and tow the midget submarine.
N tip of O-Shima. HAGOROMO MARU stops her escort duty at a point seven nms N of Kazahaya-Saki at 34-48N, 139-22E and begins searching for the drifting midget submarine.
21 September 1944:
HAGOROMO MARU discovers HA-75 and takes her in tow.
22 September 1944:
HAGOROMO MARU and HA-75 arrive at Yokosuka, where the midget submarine is taken over by the Harbor-Master's Office.
The same day, HAGOROMO MARU arrives at Nagaura.
24 September 1944:
HA-71 arrives at Chichi-jima.
5 January 1945:
Two miles SW of Chichi-jima. USN PB4Y-1s (B-24-type “Liberator”) heavy patrol bombers of VPB-111 bomb and sink HA-71.
16 March 1945:
Iwo Jima is declared secured. After Iwo falls, Chichi-jima suffers daily air raids. Japanese radar on Chichi-jima's highest
mountain point cannot detect low flying Grumman F-6F "Hellcat" fighters that strafe the island's shipping and facilities.
27 July 1945:
Chichi-jima. By this date, the island's garrison numbers about 3,500 men.
15 August 1945: Cessation of Hostilities:
The war ends. Chichi-jima is never captured.
3 September 1945:
Aboard USS DUNLAP (DD-384) off Chichi-jima. LtGen Tachibana Yoshio, senior Japanese commander in the Ogasawaras, surrenders the islands to Commodore John H. Magruder, Jr, USN. Chichi-jima and Haha-jima's garrisons comprise 20,656 Army and Navy personnel and 2,285 civilian laborers.
(LtGen Tachibana signs the instrument of surrender aboard USS DUNLAP )
A detachment of Marines is sent to Chichi-jima to help repatriate former Japanese servicemen. They are the first American troops to set foot in the Bonins since Commodore Perry's expedition in 1853.
 Although the evidence is dubious, the islands may have been discovered in 1593 by Ogasawara Sadayori in the service of the warlords
Toyotomi and Tokugawa. In 1675, the Edo Government sent an exploration ship to investigate the islands. The expedition named the islands Bunin ("Bonin") Shima (uninhabited islands). About 1825, Captain Frederick W. Beechey’s HMS BLOSSOM claimed the islands for Britain. He renamed them the Archbishop Islands.
 The authors could find no accounts of combat sorties by any of Chichi-jima's midget submarines against Allied shipping.
-Bob Hackett, Sander Kingsepp and Erich Muehlthaler.
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