Lieutenant Colonel Clayton C. Sims served with the 393rd Infantry Regiment Camp Van Dorn, Mississippi as Assistant Adjutant and Assistant S3. He later served with the 99th Infantry Division and the 90th Infantry Division in Germany during World War II as Assistant G1. In 1946, Lieutenant Colonel Sims served with the 4th Armored Division and the 1st Infantry Division in Germany as Assistant Chief of Staff and Assistant G1. | Upon returning to the United States in 1948, Lieutenant Colonel Sims was assigned as Assistant Gl, Headquarters, 2d Army, Fort Meade, Maryland. In 1950, Lieutenant Colonel Sims became Assistant G1, U.S. Forces, Salzburg, Austria. He became a Battalion Commander and Assistant Chief of Staff, 8th Infantry Division, Fort Jackson, South Carolina, in 1953. In 1954, Lieutenant Colonel Sims went to Seoul, Korea, as Chief of Military Personnel, Headquarters 8th U.S. Army and later was assigned as Deputy G1, Okinawa. In 1957, Lieutenant Colonel Sims returned to Fort Jackson, South Carolina, as Deputy Chief of Staff.