Fleet Admiral Isoroku Yamamoto (Japanese: 山本五十六) (1884–1943) was the commander-in-chief of the Combined Fleet during World War II, a graduate of the Imperial Japanese Naval Academy and a student of the United States Naval War College and of Harvard University (1919–1921).
Yamamoto held several important posts in the Imperial Japanese Navy, and undertook many of its changes and reorganizations, especially its development of naval aviation. He was the commander-in-chief during the decisive early years of the Pacific War and so was responsible for major battles such as Pearl Harbor and Midway. He died during an inspection tour of forward positions in the Solomon Islands when his aircraft (a G4M Betty bomber) was ambushed by American P-38 Lightning fighter planes. His death was a major blow to Japanese military morale during World War II.
Isoroku Yamamoto carried out the attack on Pearl Harbor and the subsequent invasion of Hawaii. He also helped defeat the USA's first attempt to retake the Hawaii in June, 1942.
Yamamoto had the respect of the entire Japanese military establishment. Even Army leaders revered the admiral, despite the traditional rivalry between the army and the navy. Thus, when Commander Minoru Genda concluded in March, 1941 that Japan must invade Hawaii rather than simply attacking the American naval base at Pearl Harbor, he brought his plan to Yamamoto. Yamamoto was persuaded by Genda's arguments, although he retained his own reservations that the American industrial complex would readily overwhelm Japan in the long run. Yamamoto personally planned the attack and invasion of Hawaii in December, 1941 through February, 1942.
In 1942, Yamamoto traveled to Hawaii at the insistence of the naval forces present, who anticipated an American a counter-invasion by the summer. From the Akagi, Yamamoto oversaw the utter defeat of the over-confident American forces.
However, Yamamoto's concerns proved prophetic. The Americans returned in 1943 with a far superior force. Yamamoto was not present in Hawaii when Japan was defeated and her forces crushed.