Leahy, William Daniel, 1875–1959, American naval officer and diplomat, b. Hampton, Iowa. He served in the Spanish-American War, in the Philippines, then in Nicaragua (1912), in Haiti (1916), in the Mexican expedition (1916), and in World War I. He later became chief of naval operations (1937) and governor of Puerto Rico (1939), and he served (1940–42) as ambassador to Vichy France. In 1942, he became chief of staff to President Franklin Delano Roosevelt, who made him (1944) a fleet admiral (five-star admiral). He continued as chief of staff under President Truman until 1949. He wrote I Was There (1950).