Sargent joined the United States Army and by March 15, 1967 was serving as a first lieutenant in Company B, 4th Battalion, 9th Infantry Regiment, 25th Infantry Division during the Vietnam War. On that day, while in Hau Nghia Province of the Republic of Vietnam. For his actions on that day, he was posthumously awarded the medal, America’s highest military decoration.
His citation partially reads, “For conspicuous gallantry and intrepidity in action at the risk of his life above and beyond the call of duty. While leading a platoon of Company B, 1st Lt. Sargent was investigating a reported Viet Cong meeting house and weapons cache……..As they approached another Viet Cong emerged and threw 2 hand grenades that landed in the midst of the group. 1st Lt. Sargent fired 3 shots at the enemy then turned and unhesitatingly threw himself over the 2 grenades. He was mortally wounded, and his 2 companions were lightly wounded when the grenades exploded.
By his courageous and selfless act of exceptional heroism, he saved the lives of the platoon sergeant and forward observer and prevented the injury or death of several other nearby comrades.” The Ruppert Leon Sargent Memorial City Administration Building in Hampton was dedicated in 2002.