Grant joined the Army from Boston, Massachusetts in 1958, and was killied in action on November 13, 1966 was serving as a first lieutenant in Company A, 1st Battalion, 14th Infantry Regiment, 25th Infantry Division. During a firefight on that day in the Republic of Vietnam, Grant organized his group's defense and repeatedly exposed himself to enemy fire to rescue wounded soldiers, despite being wounded himself, before he was killed in a mortar attack. He was posthumously promoted to captain and, on January 29, 1968, issued the Medal of Honor for his actions during the battle.