After serving in the Army Air Forces in World War II, I.G. Brown transferred to the U.S. Air Force when it became a separate branch of service in 1947. During the Korean War recall of the Air National Guard, General Brown was voluntarily recalled to active duty to serve as Chief of Operations, Air Division, National Guard Bureau. from 1969 to 1974 he was the First Director of the Air National Guard. He retired as a U.S. Air Force Major General.