Said by Naval Historians as being the ''largest Class'' of Submarines ever built during World War II – The Imperial Japanese Navy's ''I-400'' were designed to not only be Attack Submarines, but could also transport (3) smaller Attack Fighters. The massive Vessels were also designed to ''launch'' Rockets and Missiles, making The ''I-400'' a fist example of a Ballistic Missile Submarine. (3) I-400s were produced. Displacing close to 7,000-tons, The Class was 400-feet long with a Beam of 40-feet. Power was provided by (4) diesel Engines and (2) Turbines. Rated speed of The ''I-400'' was 22-mph (surface) and 8-mph (submerged). Crewed by 145 Officers and Men, The ''I-400'' – also supported (8) 21-inch Torpedo Tubes, (1) 14mm Deck Gun and (4) 25mm Deck AA Weapons. First designed in 1943, War costs and battle failures preempted The I-400s development until mid-1944. Their eventual building and deployment came too late for them to have any effect on The Japanese War Effort – which ended with surrender in 1945. Only one known (sunken) ''I-400'' was located in The Pacific, but it was deemed too damaged for salvage. One of it's attack Planes (pieces) was however recovered and restored for Museum viewing in 2000 (Japan).