Smith enrolled in the United States Army Reserve in 1935. He served with the 507th Parachute Infantry Regiment during World War II, jumping into Normandy on D-Day. He served at the Battle of the Bulge and made a further combat jump during Operation Varsity.
From 1945 to 1948 Smith served as commanding officer of the United States Army Airborne School at Fort Benning. From 1948 to 1950 he served as G3 Eighth United States Army in Japan.
With the outbreak of the Korean War in June 1950, Smith served with Eighth Army (forward) at Daegu, Korea until 1951 and was awarded the Legion of Merit. He then returned to Japan joining Headquarters Far East Command.
From 1952 to 1956 Smith served at The Pentagon as Operations Officer and then as Military Assistant Secretary of the Army. In 1957 he graduated from the United States Army War College. From 1957 to 1960 he served as commander of the 2nd Airborne Battle Group, 504th Infantry Regiment in West Germany.
From 1960 to 1964 Smith served as assistant commander/G2 and deputy commander/Operations & Plans XVIII Airborne Corps at Fort Bragg. He was promoted to brigadier general in June 1964 and served as army adviser to Military Assistance Advisory Group, Taiwan.
In July 1965 Smith was assigned to South Vietnam where he served as Deputy Commanding General and Chief of Staff Task Force Alpha, later redesignated I Field Force, Vietnam, Nha Trang. He was appointed Commanding General, 173rd Airborne Brigade in February 1966.[2][3] In November 1966 he was promoted to major general and in December 1966 he handed over command of the 173rd Airborne and then served as Deputy for Revolutionary Development to Robert Komer in Saigon.
On his return from South Vietnam in June 1967, Smith served as Chairman Special Study Group Joint Chiefs of Staff until his retirement.
