The United States Armed Forces are the military forces of the United States. U.S. federal law names six armed forces: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. Since 1949, all of the armed forces, except the Coast Guard, have been permanently part of the United States Department of Defense, with the Space Force existing as a branch of the Air Force until 2019. They form six of the eight uniformed services of the United States.
From their inception during the American Revolutionary War, the Army and the Navy, and later the other services, have played a decisive role in the country's history. They helped forge a sense of national unity and identity through victories in the early-19th-century First and Second Barbary Wars. They played a critical role in the territorial evolution of the U.S., including the American Civil War. The National Security Act of 1947 created the Department of Defense or DoD, (after a short period being called the National Military Establishment) headed by the secretary of defense, superior to the service secretaries. It also created both the U.S. Air Force and National Security Council; in 1949, an amendment to the act merged the cabinet-level departments of the Army, Navy, and Air Force into the DoD.
