On 24 May 1942, Admiral Isokuru Yamamato was a troubled but confident man. He and his staff had just finished up his final wargame for Operation MI, the invasion of the Aleutians and Midway Island. It was a resounding success… but only because his chief of staff declared the results of two Japanese carriers sunk as unrealistic. That was half of his current force of four carriers. He was troubled not because of the result of the game but because he only had four carriers: the Kido Butai should have six. Unfortunately, the Zuiakaku and Shokaku inexplicably returned to Japan after the Battle of the Coral Sea instead of returning to his main base at Truk, the Japanese version of Pearl Harbor in the Central Pacific where they could make repairs and cross level planes. And they could not be called back without delaying the operation. He had lost 1/3 of his main strength before the battle even began.
Yamamoto still had many advantages. His aircrews had infinitely more experience than the green American airmen. Also, even without his two wayward carriers, he still outnumbered the Americans 2 to 1 in that all-important class of ship. But most importantly, he believed he would have the element of surprise in the coming battle. Yamamoto was sure the Americans would react to an invasion of Alaska and he would ambush them at Midway as they did so. Four carriers should be more than enough. On the morning of 25 May, 1942, the various Japanese task forces would begin leaving their home ports for the intricate and complicated Operation MI.
Up to that time, Admiral Yamamoto’s Japanese Combined Imperial Fleet of four fleet carriers, seven battleships, and 174 other ships was the largest and most powerful naval force ever assembled for a single purpose in human history. The vast majority of it was headed directly for the Hawaiian Islands, specifically the tiny island of Midway.