The U.S. armed forces were originally established at the time of the Continental Congress. Following WWII, the armed forces evolved into a permanent necessity for national defense. There are five branches of service: the Air Force, Army, Coast Guard, Marines and the Navy. All branches of military service are mechanisms of the Dept. of Defense, except for the U.S. Coast Guard, a component of the Dept. of Homeland Security. In addition to the five branches of service, there are seven reserve components: the Army Reserve, Army National Guard, Navy Reserve, Marine Corps Reserve, Air Force Reserve, Air National Guard and Coast Guard Reserve.