Isoroku Yamamoto (山本 五十六, Yamamoto Isoroku, April 4, 1884 – April 18, 1943) was a Marshal Admiral of the Imperial Japanese Navy (IJN) and the commander-in-chief of the Combined Fleet during World War II until he was killed. Yamamoto held several important posts in the IJN, and undertook many of its changes and reorganizations, especially its development of naval aviation. He was the commander-in-chief during the early years of the Pacific War and oversaw major engagements including the attack on Pearl Harbor and the Battle of Midway.