Colonel John C. Coleman was commissioned an Infantry Officer from Officer Candidate School on 1 September 1970. His first duty assignment was as Weapons Platoon Leader, Company C, 1st Battalion 279 Infantry, 45th Infantry Brigade, Oklahoma Army National Guard, Nowata, Oklahoma. | His subsequent duty assignments include: Liaison Officer, Headquarters, Headquarters Company, 1st Battalion 279th Infantry, 45th Infantry Brigade, Oklahoma Army National Guard, Tulsa, Oklahoma;  Company Commander, Support Company, 1st Battalion 279th Infantry, 45th Infantry Brigade, Tulsa, Oklahoma;  S-3 Air and S-1, Headquarters, Headquarters Company, 1st Battalion 279th Infantry, 45th Infantry Brigade, Tulsa, Oklahoma;  Commander, Company B, 1st Battalion 279th Infantry, 45th Infantry Brigade, Miami, Oklahoma;  S-3 Air, Headquarters, Headquarters Company, 1st Battalion 279th Infantry, 45th Infantry Brigade, Tulsa, Oklahoma; S-1, Headquarters, Headquarters Battery, 1st Battalion, 189th Field Artillery, 45th Field Artillery Brigade, Enid, Oklahoma;  Assistant S-3, Headquarters, Headquarters Company, 45th Infantry Brigade, Edmon, Oklahoma; S-1, Headquarters, Headquarters Company, 1st Battalion 279th Infantry, 45th Infantry Brigade, Tulsa, Oklahoma; S-1, Headquarters, Headquarters Battery, 45th Field Artillery Brigade, Enid, Oklahoma;  S-1 and Brigade Executive Officer, Headquarters, Headquarters Battery, 45th Field Artillery Brigade, Enid, Oklahoma;  Brigade Executive Officer, Headquarters, Headquarters Company, 45th Infantry Brigade, Edmond Oklahoma; Secretary to General Staff, Headquarters State Area Command, Oklahoma Army National Guard, Oklahoma City, Oklahoma; Chief of Staff, Headquarters State Area Command, Oklahoma Army National Guard, Oklahoma City, Oklahoma.