 Less than a month after the attack, Marks reported to Fort Ord as a Second Lieutenant in the United States Army.Serving in the Pacific Theater of Operations, including the Philippines Campaign (1944–45), he was the Assistant Defense Counsel for the Court of the Eighth United States Army during the Occupation of Japan.After completing his Army service as a Major, Marks returned to the UC Berkeley Law School but eventually transferred, graduating from San Francisco Law School in 1949.