Don Sinclair Davis, PhD (August 4, 1942 – June 29, 2008) was an American character actor best-known for playing General Hammond in the television series "Stargate SG-1" (1997–2007), and earlier for playing Major Garland Briggs on the television series "Twin Peaks" (1990–1991). He was also a theater professor, painter, and United States Army captain.
Don Sinclair Davis was in the air force.
It says he was in the Army. It was also possible he was in the air force at some time. This is unstated but possible.