Damato enlisted in the United States Marine Corps on January 8, 1942. He went to Derry, Northern Ireland, in May of that year. During the first year of his enlistment, he distinguished himself, volunteering for special duty with a select invasion party that took part in the North African landings. He was advanced in rate for especially meritorious conduct in action while serving aboard ship at the port city of Arzew, Algeria, on November 8, 1942. Landing with an assault wave entering the port from seaward, he assisted in boarding and seizing vessels in the harbor, and ultimately the port itself. He returned to the United States in March 1943, and three months later, sailed for duty in the Pacific.