Submarines of the Imperial Japanese Navy
Imperial Japanese Navy (IJN) submarines formed by far the most varied fleet of submarines of World War II, including manned torpedoes ("Kaiten"), midget submarines ("Kō-hyōteki", ), medium-range submarines, purpose-built supply submarines (many used by the Imperial Japanese Army, see Type 3), fleet submarines (many of which carried an aircraft), submarines with the highest submerged speeds of the conflict ("Sentaka" ), and submarines able to carry multiple bombers (World War II's largest submarine, the Sentoku ). They were also equipped with the most advanced torpedo of the conflict, the oxygen-fuelled Type 95 (which are sometimes confused with the famed Type 93 Long Lance torpedo).
History of submarines
The Germans were slower to recognize the importance of this new weapon. A submersible was initially ordered by the Imperial Russian Navy from the Kiel shipyard in 1904, but cancelled after the Russo-Japanese War ended. One example was modified and improved, then commissioned into the Imperial German Navy in 1906 as its first U-boat, "U-1". It had a double hull, was powered by a Körting kerosene engine and was armed with a single torpedo tube. The fifty percent larger "SM U-2" had two torpedo tubes. A diesel engine was not installed in a German navy boat until the class of 1912–13. At the start of World War I, Germany had 20 submarines of 13 classes in service with more under construction.