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. 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, although one source[1] states that the Yu 1001 subclass differed from the original Yu 1 sublcass in other ways, being longer, having a slightly larger displacement and more powerful diesel engine that increased the maximum speed by, and probably having no deck gun installed. None of the Yu I-type submarines carried torpedoes or had torpedo tubes. Yu 1003 a unit of the Yu 1001 subclass.[2]
Japan Steel Works (Nihon Seikojo) constructed at its plant in Hiroshima, Japan.[2] [3] Records of the details of the construction of Yu 1003 have not been discovered, but the earliest Yu I-type submarines of the original Yu 1 subclass were laid down and launched during the latter half of 1943 and entered service at the end of 1943 or early in 1944.[3] [4]
Yu 1003 spent her operational career in Japanese home waters.[5] In January 1945, several Type I transport submarines were sent to operate from Shimoda on the southern tip of the Izu Peninsula in Shizuoka Prefecture on Honshu,[1] and the submarines began transport missions from Shimoda in March 1945.[1] Assigned to Detachment 2, Transport Submarine Group, on 11 February 1945,[1] Yu 1003 made a round-trip supply voyage from Shimoda to Hachijō-jima in the Philippine Sea sometime during 1945.[1] [3]
World War II ended with the cessation of hostilities on 15 August 1945. Yu 1003 surrendered to the Allies later in August 1945.[3] She subsequently either was scuttled or scrapped.[1]