Yamaguchi attended Princeton University in the United States between 1921 and 1923 and then graduated from the Naval Staff College in 1924. He next served on the Naval General Staff. Promoted to commander in 1928, he was a member of the Japanese delegation to the 1929–1930 London Naval Disarmament Conference. Yamaguchi was promoted to captain in 1932 and then served as naval attaché in the United States between 1934 and 1937. Thereafter, he commanded the battleship Ise and the First Combined Air Fleet in China, engaged in air operations over China. Promoted to rear admiral in 1940, Yamaguchi assumed command of Carrier Division 2, composed of the aircraft carriers Hiryu and Soryu. A close confidant of Admiral Yamamoto Isoroku, he was an outspoken supporter of Yamamoto's Pearl Harbor plan and, later, his Midway plan.
Yamaguchi and the cautious Vice Admiral Nagumo Chuichi were often at odds. During the Japanese attack on Pearl Harbor, Yamaguchi urged Nagumo to make follow-up strikes on Pearl Harbor facilities and to destroy the U.S. carriers absent on 7 December 1941, but Nagumo refused. In early 1942, Yamaguchi took part in actions against the British in the Indian Ocean.
Yamaguchi and his carriers next participated in the Battle of Midway. Again, he and Nagumo disagreed on tactics. On 4 June 1942, Yamaguchi stressed the necessity for the Japanese to strike first, and on the sighting of the American carriers, he urged that the Japanese launch an immediate dive-bomber attack without the torpedo-bombers, but Nagumo refused. Nagumo's decisions left his carriers vulnerable, and three of the four were sunk by U.S. Navy dive-bombers. With his own carrier Akagi sinking, Nagumo transferred command of air operations to Yamaguchi.
Twice Yamaguchi launched attacks against what he thought were two different U.S. carriers; actually, there was only one, the Yorktown. Although Yamaguchi lost 24 aircraft, his attacking planes badly damaged the Yorktown, and she was later sunk by a Japanese submarine. As Yamaguchi prepared a third strike that evening, U.S. dive-bombers from the carriers Enterprise and Yorktown mortally damaged the Hiryu. He assumed blame for the loss of his ship and refused to leave it. His staff tried to dissuade him, as they believed that he was invaluable to the Japanese navy, but Yamaguchi rejected their appeals. The 800 survivors then abandoned ship, and Hiryu was scuttled, sinking on 5 June. Yamaguchi was last seen reciting poetry and sipping tea. William Head and Spencer C. Tucker
Dull, Paul S. A Battle History of the Imperial Japanese Navy. Annapolis, MD: Naval Institute Press, 1978.; Fuchida Mitsuo and Masatake Okumiya. Midway: The Battle That Doomed Japan. Annapolis, MD: Naval Institute Press, 1955.; Ienaga Saburo. The Pacific War: World War II and the Japanese, 1931–1945. New York: Pantheon, 1978.; Prange, Gordon W. At Dawn We Slept: The Untold Story of Pearl Harbor. New York: McGraw-Hill, 1981.; Prange, Gordon W., Donald Goldstein, and Kathleen Dillon. Miracle at Midway. New York: Penguin, 1982.
William Head and Spencer C. Tucker