Isoroku Yamamoto (山本 五十六, Yamamoto Isoroku; April 4, 1884 – April 18, 1943) was an admiral of the Imperial Japanese Navy (IJN) and the commander of the Combined Fleet during World War II. He commanded the fleet from 1939 until his death in 1943, overseeing the start of the Pacific War in 1941 and Japan's initial successes and defeats before his plane was shot down by U.S. fighter aircraft over New Guinea.
Yamamoto graduated from the Imperial Naval Academy in 1904 and served in the Russo-Japanese War, where he lost two fingers at the Battle of Tsushima. He later studied at Harvard University in the United States and was appointed naval attaché to the Japanese embassy in Washington. His experiences convinced him that naval power depended on access to oil and industrial capacity, and that Japan thus had little hope to defeat the U.S. in a war. He was one of the first naval leaders to conclude that naval aviation and aircraft carriers would play a decisive role in any future conflict. In 1936, Yamamoto was appointed navy vice minister, and opposed Japan's alliance with Germany and Italy in the Tripartite Pact of 1940.