In the final two years of World War II, the Imperial Japanese Army constructed transport submarines — officially the Type 3 submergence transport vehicle and known to the Japanese Army as the Maru Yu — with which to supply its isolated island garrisons in the Pacific Ocean. Only submarines of the Yu I type were completed and saw service. The Yu I type was produced in four subclasses, each produced by a different manufacturer and differing primarily in the design of their conning towers and details of their gun armament. None carried torpedoes or had torpedo tubes. Yu 3 was of the Yu 1 subclass.[1]
Yu 3 was laid down in 1943[2] by the itachi Kasado Works (Hitachi Kasado Seisakujo) at Kudamatsu, Japan.[1] [2] She was launched later in 1943.[2]
After her delivery to the Japanese Army, Yu 3 initially remained in Japanese home waters while the Army constructed additional submarines of her class and established a training program for their crews.[3] In May 1944, the Army created its first submarine combat unit (jissen butai), the Manila Underwater Transport Detachment (Manira Sensuiyuso Hakentai), consisting of Yu 3, her sister ships and, and a mother ship.[3] The detachment got underway from Japan on either 28[3] or 30[2] May 1944 (according to different sources) bound for Manila on Luzon in the Philippines.[3] The vessels had a difficult voyage which included a number of mechanical breakdowns, but finally arrived at Manila on 18 July 1944.[2] [3] After their arrival, the three submarines underwent repairs and thorough overhauls.[3]
On 20 October 1944, United States Army forces landed on Leyte, beginning both the Battle of Leyte and the broader Philippines campaign of 1944–1945.[3] In November 1944, all three submarines got underway on their first supply run to Leyte.[3] Yu 2 never arrived,[3] but Yu 1 and Yu 3 reached Ormoc on Leyte's west coast on 27 November 1944 and discharged a combined 600 bags of white rice, 50 boxes of field rations, and 300 boxes of radio batteries.[3]
In December 1944, Yu 1 and Yu 3 were sent to San Fernando on the northwest coast of Luzon.[3] On 5 January 1945, while Yu 3 was transporting a cargo which consisted mostly of large bags of rice and bundles of welding rods for the Luzon garrison, U.S. aircraft attacked her in Lingayen Gulf, and she ran aground.[2] [3] [4] Her crew scuttled her just off Damortis and abandoned her.[2] [3] [4]
U.S. Army forces landed on the coast of Luzon in Lingayen Gulf on 9 January 1945, and shortly afterward U.S. forces found Yu 3 lying awash in shallow water just off Damortis.[4] After United States Seventh Fleet personnel of the Seventh Fleet Intelligence Center inspected the wreck, the United States Navy decided to salvage Yu 3.[4] The U.S. Navy rescue and salvage ship refloated her on 18 January 1945,[4] [5] and she was towed across Lingayen Gulf to Sual.[4] U.S. personnel examined her there, finding her cargo still aboard and no sign of any battle damage.[4] Yu 3 subsequently was loaded aboard the dock landing ship,[4] [5] which transported her to the United States in May 1945.[5] By no later than early June 1945 Yu 3 was at Mare Island Navy Yard in Vallejo, California.[5]
An article in the 8 June 1945 issue of the Mare Island Navy Yard's newspaper, The Grapevine, described Yu 3 as a 137feet, 280-ton Japanese "cargo-carrying submarine" of crude construction powered by two six-cylinder diesel engines.[5] The article said that she had no interior bulkheads and that her periscope operated by counterweights,[5] and so could be raised only 3feet. An article in the 22 June 1945 issue of The Grapevine identified her as Yu 3 and reported that the navy yard was offering tours of her and selling parts from her to raise money for war bonds.[5] She subsequently probably was either scrapped or scuttled, sometime after early July 1945.[3] [5]