Japanese submarine I-156

The Japanese submarine I-156 was a cruiser submarine of the KD3B sub-class built for the Imperial Japanese Navy (IJN) during the 1920s. She supported Japanese forces during the invasion of Malaya in December 1941 and the Dutch East Indies campaign in early 1942.

Design and description
The submarines of the KD3B sub-class were essentially repeats of the preceding KD3A sub-class with minor modifications to improve seakeeping. They displaced 1800 LT surfaced and 2300 LT submerged. The submarines were 101 m long, had a beam of 8 m and a draft of 4.9 m. The boats had a diving depth of 60 m and a complement of 60 officers and crewmen.

For surface running, the boats were powered by two 3400 bhp diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 900 hp electric motor. They could reach 20 kn on the surface and 8 kn underwater. On the surface, the KD3Bs had a range of 10000 nmi at 10 kn; submerged, they had a range of 90 nmi at 3 kn.

The boats were armed with eight internal 53.3 cm torpedo tubes, six in the bow and two in the stern. They carried one reload for each tube; a total of 16 torpedoes. They were also armed with one 120 mm deck gun for combat on the surface.

Construction and career
Built by the Kure Naval Arsenal, I-56 was laid down on 3 November 1926, launched on 23 March 1928 and completed on 31 March 1929. In November 1941, the boat was assigned to the 19th Submarine Division of the 4th Submarine Squadron. The division departed its base at Samah on Hainan Island, China on 1 December for their patrol area off Trengganu, Malaya.