I received most of my information from the book "Operation Storm: Japan's Top Secret Submarines and Its Plan to Change the Course of World War II" by John Geoghan, I recommend you guys read it if you find this interesting and other Japanese plans to attack the U.S. mainland. After Japan had attacked Pearl Harbor, Japanese Admiral Isoroku Yamamoto told his colleagues in the Japanese High command that he could give them 6 months of hard fighting against the Americans, after that nothing could be guaranteed. Yamamoto, being a professional gambler (Seriously he was really damn good at it and threatened multiple times to leave the military and take it up professionally) thought up an audacious plan, one with the same daring and shock as Pearl Harbor, one that would hopefully make the Americans sue for peace. He called it "[i]Operation Storm[/i]" "Operation Storm" called for 14-18 I-400 Submarines to travel to the east coast of the United States and launch an aerial surprise attack against New York city and Washington D.C. Now these submarines weren't any normal kind, the I-400 was capable of carrying 3 Aichi M6A float planes, making it basically an underwater aircraft carrier. The I-400 was often mistaken in aerial reconnaissance photographs as a surface ship such as a destroyer or light cruiser, they never thought something so big could be an submarine. American subs were hardly half the size of that monster and no American submarine would be bigger until 1959 when we launched our first ballistic missile submarine. These planes were some of the most advanced of its time, capable of being able to fold into a space of 10-feet in the submarines hold, and to be launched from a catapult mechanism on the top deck, they were also painted in American scheme to fool air defenses. They could also be easily retrieved once there mission was completed by landing on the water near the submarine as they were float planes. Yamamoto hoped that they could launch a 40 plane attack against each city and completely demoralize the American people and there government. I-400's were easily suited for the job, they could travel the world one and a half times over without stopping to refuel, a feat no submarine could do out of every other country in the world during the war. Each plane in there hangars could carry a sufficient armament of incendiarys and bombs to damage cities, and this attack was specifically designed to target metropolitan areas. Something unheard of in the world, no one ever thought a submarine capable of such an attack nor dreamed of it! "Operation Storm" never came to pass as many I-400's were discovered during there passage and American patrols increased, I-400's did however raid the west coast and cause minimal damage, these raids were the first time since 1812 when American soil was directly attacked. The influence of the I-400's can be traced all the way up to our most recent class of intercontinental ballistic submarine, it stands as the first type of submarine ordered to attack a city and with the capability to do so. (Not including the Germans theorized design to launch a V-2 from a U-Boat as it never came to be tested fully nor was it operational to any extent at all) Picture- One of the very few if not only picture of an I-400 in active service during World War 2, as you can see it is a massive submarine, its crew compliment was 204 officers and crew and it had 6 torpedo tubes in front. It weighed 6 tons and measured up to 122 meters in length, making it the largest submarine in existence until 1959 when the U.S. launched its first ballistic missile submarine. Today the only I-400 that could be found and studied was found off the coast of an Hawaiian island in 2005, it is largely intact. There is a surviving float plane as well that is on display at the National Air and Space Museum in Washington D.C., ironically where it was supposed to attack. As always if you like World War 2 and stuff like this feel free to follow me to stay tuned on my posts and please ask any questions you may have!