William D. Leahy | |
|---|---|
 Leahy c. 1945 | |
| Chief of Staff to the Commander in Chief | |
| In office 20 July 1942 – 21 March 1949 | |
| President | |
| Preceded by | Office established |
| Succeeded by | Omar Bradley (as Chairman of the Joint Chiefs of Staff) |
| United States Ambassador to France | |
| In office 8 January 1941 – 1 May 1942 | |
| President | Franklin D. Roosevelt |
| Preceded by | William Christian Bullitt Jr. |
| Succeeded by | Jefferson Caffery |
| Governor of Puerto Rico | |
| In office 11 September 1939 – 28 November 1940 | |
| President | Franklin D. Roosevelt |
| Preceded by | Blanton Winship |
| Succeeded by | Rexford Tugwell |
| Chief of Naval Operations | |
| In office 2 January 1937 – 1 August 1939 | |
| President | Franklin D. Roosevelt |
| Preceded by | William Harrison Standley |
| Succeeded by | Harold Rainsford Stark |
| Personal details | |
| Born | William Daniel Leahy 6 May 1875 Hampton, Iowa, U.S. |
| Died | 20 July 1959 (aged 84) Bethesda, Maryland, U.S. |
| Resting place | Arlington National Cemetery |
| Relations | William Harrington Leahy (son) |
| Military service | |
| Branch/service | United States Navy |
| Years of service | 1893–1959 |
| Rank |  Fleet Admiral |
| Commands | |
| Battles/wars | |
| Awards | |
William Daniel Leahy (/ˈleɪhiˌ ˈleɪ.i/) (6 May 1875 – 20 July 1959) was an American naval officer. The most senior United States military officer on active duty during World War II, he held several titles and exercised considerable influence over foreign and military policy. As a fleet admiral, he was the first flag officer ever to hold a five-star rank in the U.S. Armed Forces.
An 1897 graduate of Annapolis, Leahy saw active service in the Spanish–American War, the Philippine–American War, the Boxer Rebellion in China, the Banana Wars in Central America, and World War I. He was the first member of his cadet class to reach flag rank, as the Chief of the Bureau of Ordnance from 1927 to 1931. He subsequently served as Chief of the Bureau of Navigation from 1933 to 1936, and commanded the Battle Fleet from 1936 to 1937. As Chief of Naval Operations from 1937 to 1939, he was the senior officer in the United States Navy, overseeing the expansion of the fleet and preparations for war.
After retiring from the Navy, Leahy was appointed the governor of Puerto Rico in 1939 by President Franklin D. Roosevelt. In his most controversial role, he served as the Ambassador to France from 1940 to 1942. American policy was aimed at keeping the government of Vichy France free of German control, but Leahy had limited success. He came to believe that the United States should back Free France instead of Vichy France, and asked to be recalled after the Japanese attack on Pearl Harbor brought the United States into the war.
Leahy was recalled to active duty as the Chief of Staff to the President in 1942 and served in that position for the rest of the war. He was the highest-ranking active-duty member of the military. As the de facto first Chairman of the Joint Chiefs of Staff, he oversaw all of the American armed forces. He also presided over the American delegation to the Combined Chiefs of Staff. He was a major decision-maker during the war and was second only to the President in authority and influence. Leahy was promoted to five-star rank in December 1944. He served Roosevelt's successor Harry S. Truman, helping shape postwar foreign policy until he retired in 1949. Although he did not oppose the use of the nuclear weapons during the war, in the post-war period he rejected war plans that placed too much emphasis on the first use of nuclear weapons.