Caption: "Marines and a Navy medical corpsman in Korea fasten the casualty rig of a helicopter as the pilot prepares to carry the wounded man to a rear area hospital." A hospital corpsman (HM) is an enlisted medical specialist of the United States Navy who serves with U.S. Navy and who may be assigned temporary duty with the United States Marine Corps or Fleet Marine Force. They are the only enlisted corps in the United States Navy. Hospital corpsmen accompanied Marine units into battle during the Korean War.