Submarines of the Imperial Japanese Navy
Imperial Japanese Navy submarines originated with the purchase of five Holland type submarines from the United States in 1904. Japanese submarine forces progressively built up strength and expertise, becoming by the beginning of World War II one of the world's most varied and powerful submarine fleets.
Submarines of the Imperial Japanese Navy
The submarines were double-hulled medium sized submarines. They were derived from the (KT or K5 type, "Ro-29"-class). Several variants existed. From 1934 to 1944, the (K6 type, "Ro-33"-class) and the (K7 type, "Ro-35"-class) were built. The K6 type was equipped with a 3.25 inch (80 mm) gun and Type 95 Long Lance torpedoes. Twenty units were built: , , "Ro-35", "Ro-36, Ro-37", "Ro-38", "Ro-39", "Ro-40", "Ro-41", "Ro-42", "Ro-43", "Ro-44", , "Ro-46", "Ro-47", "Ro-48", "Ro-49", "Ro-50", "Ro-55", "Ro-56".