He left school before graduating to join the United States Marine Corps during World War II, enlisting the day after the attack on Pearl Harbor. He was wounded in 1942 during the invasion of the Solomon Islands and was sent to a hospital in San Francisco to recuperate. According to an account published in newspapers across the United States, Combs was attacked by eight Japanese soldiers; he killed seven of them with his machine gun and, when the gun jammed, he disarmed the eighth Japanese soldier and "slit his throat" with a bayonet. Combs received a presidential citation and a Purple Heart for his service. After recovering from his wounds, Combs returned to action in the Pacific. He was killed during the invasion of Iwo Jima on February 19, 1945. In 1986, Combs was posthumously inducted into the University of Michigan Athletic Hall of Honor.