William Thurman was appointed a second lieutenant in the Infantry Reserve in May 1931, and he was transferred to the Judge Advocate General Reserve in December 1937. After receiving his law degree he practiced law in Atlanta. Recalled to active duty in 1941, after serving in the Army Air Forces in World War II, he transferred to the U.S. Air Force when it became a separate branch of service in 1947. He retired in 1969 as a U.S. Air Force Major General.