 He enlisted in the U. S. Marine Corps Reserve in Brooklyn, New York on December 26, 1967 and was subsequently discharged to enlist in the Regular Marine Corps on January 31, 1968.Private Noonan completed recruit training with the 3rd Recruit Training Battalion, Marine Corps Recruit Depot Parris Island, South Carolina in April 1968, and was promoted to private first class on April 1, 1968.Transferred to the Marine Corps Base Camp Lejeune, North Carolina, he underwent individual combat training with the 1st Battalion, 1st Infantry Training Regiment.