Allan Kelton served briefly in the Navy during the Civil War, and after the war served for two years in the U.S. Army. He attended the U.S. Naval Academy at Annapolis, Class of 1866 but did not graduate with his class, and was subsequently commissioned in the Marine Corps. His older brother was a graduate of the U.S. Military Academy and served in the Civil War and later became Adjutant General of the Army. Allan Kelton retired as a Colonel of Marines in 1909, after more than 40 years of service in the Navy, Army, and Marine Corps.