Prior to attending Officer Candidate School, Colonel Harold H. Roberts III served in the Tennessee and Georgia National Guard. His assignments were Armor Crewman and Battalion Supply Clerk. Colonel Roberts was commissioned as a Field Artillery Officer after graduating from Officer Candidate School (Reserve Component), Class 2-74 at Fort Benning, Georgia on 16 August 1974. His first duty assignment was Battalion Ammunition Officer, SVC Battery 1/115 Field Artillery Battalion Shelbyville, Tennessee.

His subsequent duty assignments include: Assistant Executive Officer, B Battery 1/115 FA BN; Battery Commander/S4, SVC Battery 1/115 FA Battalion; Battery Commander, HHQ Battery 1/115 FA Battalion; Training Development Officer/Instructor, Tennessee Military Academy; Senior Tactical Officer, Tennessee Military Academy; Assistant Operations/Plans Officer, Tennessee Military Academy, S-3, Tennessee Military Academy; Chief Exam/Auditor, HQ STARC, attached to DET3-STARC(TMA), as S-3; Executive Officer, DET 3, STARC, (TMA); Deputy Director, Facilities Engineer HQ STARC(-) attached to DET 3 STARC, (TMA); Supply Management Officer HQ STARC(-); Installation Commander, Catoosa Training Center, HQ TNANG, Chief Environmental Section, HQ, TNARNG; Commander(1stBN), 117thFA TNG, 117th Regiment, TN; S-3, HHT 278th ACR, Knoxville, Tennessee; Commander, 1/278 ACR, Athens, Tennessee; Administrations Officer, HQ TNARNG, STARC (-); Chief, 230th Army Liaison Team, Smyrna, Tennessee; U.S. Liaison Officer to the International Security Assistance Force, Kabul, Afghanistan.

His military education and training includes: Field Artillery Advanced Course, Chemical Advanced Course, Command and General Staff College.

His highest military awards include: Legion Of Merit, Bronze Star Medal Meritorious, NATO Medal, Global War on Terrorism Service Medal, and Global War on Terrorism Expeditionary Medal.

COL Roberts Army National Guard service coincided with his civilian career as a teacher, head football coach, and high school principal.