Colonel Duncan M. Thompson, Sr. was commissioned an Infantry Officer upon graduation from Officer Candidate School 6 March 1969. His first duty assignment was as Executive Officer, Operational Detachment A, 6th Special Forces Group (Airborne), Fort Bragg, North Carolina. | His subsequent duty assignments include: Executive Officer, Detachment 13, Company B, 46th Special Forces Company (ABN), LopBuri, Thailand;  Commander, Field Training Team #1, 46th Special Forces Company (ABN), Ubon, Thailand; Commander, Detachment 5 and Executive Officer, Company C, 5th Special Forces Group (ABN), Fort Bragg, North Carolina; Commander, Team #4, Joint Casualty Resolution Center, Ekp, Thailand; Instructor, Tower Committee, Airborne Department, United States Army Infantry School, Fort Benning, Georgia; S-3 and Engineer Officer, 2d Battalion, 12th Special Forces Group (ABN), United States Army Reserve, Tulsa, Oklahoma; MOBDES Officer, United States Army J.F. Kennedy Center for Military Assistance, Fort Bragg, North Carolina; Instructor-OCS Alabama Military Academy, Alabama Army National Guard, Fort McClellan, Alabama; Commander, Company B, 1st Battalion, 167th Infantry (MECH), Montgomery, Alabama; Commander, Operational Detachment A, Company A, 20th Special Forces Group (ABN), Montgomery, Alabama; Assistant S-3 Officer, 2d Brigade, 24th Infantry Division, Schofield Barracks, Hawaii; Commander, Company B, 1st Battalion, 14th Infantry, Schofield Barracks, Hawaii; Post Commander, United States Army Support Command, Hawaii, Fort DeRussy, Hawaii; Commandant, Hawaii Military Academy, Hawaii Army National Guard, Fort Ruger, Hawaii; Executive Officer, 100th Battalion, 442d Hawaii, Fort DeRussy, Hawaii; Assistant Deputy Chief of Staff, Training, Headquarters, 83d United States Army Reserve Command, United States Army Reserve, Columbus, Ohio; and Commander, 2d Battalion, 11th Special Forces Group (ABN), Reynoldsburg, Ohio; and Special Projects Officer, Headquarters, State Area Command, Ohio Army National Guard, Columbus, Ohio.