Colonel Roy R. Trumble was commissioned an Infantry Officer upon graduation from Officer Candidate School, 1 May 1970. His first duty assignment was as Platoon Leader, Company C, 4th Battalion, 10th Infantry, Fort Davis, Panama. | His subsequent duty assignments include: Motor Officer, Headquarters  and Headquarters Company, 4th Infantry Battalion, 10th Infantry, Fort Davis, Panama; Company Executive Officer, Combat Support Company, 4th Infantry Battalion, 10th Infantry, Fort Davis, Panama; Adjutant, Detachment Executive Officer and Detachment Commander, Company C, 3rd Battalion, 7th Special Forces Group, Airborne, Fort Gulick Panama; Assistant S3, 3rd Battalion, 47th Infantry, Company Commander, Combat Support, 3rd Battalion, 47th Infantry, and G3 Operations Officer, Headquarters and Headquarters Company, Fort Lewis, Washington; Area Commander, U.S. Army Recruiting Command Little Rock, Shreveport, Louisiana; Company Commander, Company A, 3rd Battalion, 7th Special Forces Group, Fort Gulick, Panama; Battalion Executive Officer,  3rd Special Forces Battalion (Airborne), Fort Davis, Panama; Branch Chief, U.S. Army Forces Command, Fort McPherson, Georgia; Battalion Commander, 3rd Battalion, 7th Special Forces Group (Airborne), Fort Davis, Panama; Chief Special Operations Detachment, Joint Readiness, Fort Polk, Louisiana, Chief, U.S. Army Element Military Assistance Advisory Group Peru, Lima, Peru; Commandant, U.S. Army School of the Americas, Fort Benning, Georgia.