This was a Japanese campaign against Allied ships and naval bases in the central Pacific using suicide craft such as the ‘Shinyo’ class one-man launch, ‘Kaiten 1’ class one-man torpedo, and ‘Kaiten 2’ and ‘Kaiten 4’ class two-man submarines (11 January 1945 onward).
On 11 January the Japanese submarine I-36 launched four ‘Kaiten’ craft off Ulithi: one exploded a few yards from the ammunition ship Mazama and another possibly sank the landing craft LCI-600. On 12 January I-47 launched four ‘Kaiten’ off Hollandia: there were two explosions near the 7,247-ton transport Pontus H. Ross, and one ‘Kaiten’ failed to explode.
Planned attacks by I-53 in the Kossol Passage in the Palau group, by I-56 on Manus in the Admiralty islands, and by I-58 on Apra Harbor on Guam did not materialise. Also unsuccessful was an attack by I-48 on Ulithi on 20 January, and the Japanese submarine was sunk on 21 January by the US destroyer escorts Conklin, Corbesier and Raby.