The United States military was formed by the second Continental Congress to defend against the British Empire in the American Revolutionary War. The Army, Marine Corps, and Navy were commissioned in 1775, in anticipation of the declaration of independence in 1776. The Coast Guard started as the Revenue Cutter Service in 1790. The United States Air Force originated as the Aeronautical Division of the U.S. Signal Corps in 1907 and became an independent service in 1947.