On July 23, 1966, Smith was sent to the Republic of Vietnam and served as Platoon Sergeant of the 1st Platoon, Company C, 2d Battalion, 8th Infantry of the 4th Infantry Division. The division performed combat operations in the western Central Highlands along the border between Cambodia and Vietnam. The division experienced heavy combat against North Vietnamese Army (NVA) regular forces in the mountains surrounding an area called Kontum.