Marvin was inducted 1 December 1943. While in Europe during World War II, he was in the 29th Division and participated in the Battle of the Bulge and other battles in the European Theater. During his second tour of duty in Europe, Marvin served for a time as a guard at the War Crimes Trials at Nuremberg. He returned to the U.S. in December 1949 and was stationed at Fort Benning, Georgia until being sent to Korea in August 1950. Between August 1950 and 30 November 1950, Marvin was a Weapons Platoon Sergeant. He trained men in the use of the 60 Millimeter Mortar Shells and the firing of 57 Millimeter Recoilless Rifles.
On 30 November 1950, Marvin was captured by the Chinese Communists at Chosen Reservoir and was a prisoner until 31 August 1953 when he was repatriated and returned to the United States in September 1953.
He was then assigned to the Mine Warfare Committee of the Weapons Department, Fort Benning, Georgia. Later he was assigned at Fort Sill, Oklahoma for training on Corporal and Redstone Missiles. He was assigned to a test team for Redstone and Pershing Missiles.
Marvin was discharged 31 December 1963 and received the Good Conduct Medal; the Bronze Clasp with three Loops; the Army Commendation Medal with one Oak Leaf Cluster; the American Campaign Medal; the European-African-Middle Eastern Campaign Medal with three Bronze Stars; the World War II Victory Medal; the World War II Occupation Medal; the National Defense Medal; the Korean Service Medal with five Bronze Stars and one Bronze Arrowhead; the United Nations Korean Service F/S Medal; the Combat Infantryman Badge and numerous Letters of Commendations for Outstanding Performance.