Colonel Clark D. Gilbertson was commissioned an Infantry Officer upon graduation from Officer Candidate School 17 August 1964. His first duty assignment was as Platoon Leader, 2d Battalion, 136th Infantry, Minnesota Army National Guard. | His subsequent duty assignments include: Platoon Leader, Company A, 4th Battalion, 39th Infantry, 9th Infantry Division, Fort Riley, Kansas and the Republic of Vietnam; Company Commander, Company A, 4th Battalion, 39th Infantry, 9th Infantry Division, Republic of Vietnam; S-1, U.S. Army Reception Station, Fort Jackson, South Carolina; Company Commander, U.S. Army Preparatory Training Detachment, Fort Jackson, South Carolina; Assistant S-3., 1st Battalion, 7th Cavalry, 1st Cavalry Division, Republic of Vietnam; S-4, 4th Battalion, 23d Infantry, 172d Arctic Light Infantry Brigade, Fort Richardson, Alaska; Company Commander, Company C (Airborne), 4th Battalion, 23d Infantry, 172d Arctic Light Infantry Brigade, Fort Richardson, Alaska; Assistant Professor of Military Science, Augusta College Senior ROTC Detachment, Augusta, Georgia; S-1, 2d Brigade, 82nd Airborne Division, Fort Bragg, North Carolina;  Battalion Executive Officer, 1st Battalion, 509th Parachute Infantry Regiment, 82nd Airborne Division, Fort Bragg, North Carolina; Battalion Commander, Troop Command, Fort Jackson, South Carolina; Battalion Commander, 1st Battalion, 509th Parachute Infantry Regiment, Joint Readiness Training Center, Fort Chaffee, Arkansas; Inspector General, 8th U.S. Army, Yongsan, Korea; and Deputy Chief of Staff Training, Fifth U.S. Army, Fort Sam Houston, Texas.