Henry Harley Arnold, byname Hap Arnold, (born June 25, 1886, Gladwyne, Pennsylvania, U.S.—died January 15, 1950, Sonoma, California), air strategist, commanding general of the U.S. Army Air Forces in World War II.
After graduating from the United States Military Academy at West Point, New York, in 1907, Arnold served in the infantry and then transferred to the aeronautical section of the Signal Corps, receiving his flying instruction in 1911 from Orville Wright. During World War I he rose from captain to colonel and was eventually the executive officer to the chief of the air service. In the decade of demobilization and disarmament after the war, he was one of the apostles of strategic air power, following the lead of General William (“Billy”) Mitchell. In 1931 he was appointed commanding officer at March Field, California, where he worked on the organization and tactics that were to be employed in World War II.
Arnold reported to Washington, D.C., in 1936 as assistant chief of the Army Air Corps. When his superior, General Oscar Westover, was killed in a plane crash in 1938, Arnold succeeded him as chief. Anticipating the coming global conflict, Arnold strongly pressed for increased Air Corps appropriations and aid to the Allies, despite the hostility of isolationists and shortsighted officers in the military. In 1941 he published, in collaboration with Colonel (later General) Ira C. Eaker, a book entitled Winged Warfare.
During World War II, Arnold commanded the U.S. Army Air Forces throughout the world. He also served as air representative on the U.S. Joint Chiefs of Staff and on the Anglo-American Combined Chiefs of Staff. In these capacities he was an influential architect of the plans and strategy that resulted in Allied victory. In December 1944 he was one of four army leaders promoted to the five-star rank of general of the army. He retired from service in 1946, and in 1949 his title was changed to general of the air force; he was the only air commander ever to attain the rank of five stars.
Arnold had long planned and advocated that the air forces should have parity with the army and navy in the American military establishment. The creation of the National Defense Act of 1947, which authorized this organization, was undoubtedly due in no small measure to Arnold’s effort and influence. His autobiography, Global Mission (1949), includes a history of American military aviation.