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United States Armed Forces

Combined military forces of the U.S.

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Through Military, American Revolutionary War and World War I

Established 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 contributed to early national consolidation through conflicts such as the Barbary Wars and the War of 1812, shaped the country's territorial evolution, and were involved in global conflicts including World War I, World War II, the Cold War, and the war on terror. The National Security Act of 1947 reorganized the military establishment by creating the DoD, the Air Force, and the 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. formalizing a unified defense structure under civilian control. The Space Force was established in 2019 as the newest branch.

The president of the U.S. serves as commander-in-chief and exercises authority over the armed forces through the DoD and, for the Coast Guard in peacetime, DHS. Since 1973, the United States has maintained an all-volunteer force, although the Selective Service System remains authorized to conscript most male citizens and residents aged 18 and 25 to register. All six services are also among the eight uniformed services of the United States. The armed forces consist of active-duty personnel, Reserve components, and the National Guard.

The U.S. Armed Forces are widely considered the world's most powerful and most advanced military. The military expenditure of the U.S. was US $957 billion in 2025, the highest in the world, accounting for 33% of the world's military expenditures. The personnel size of the six armed forces together ranks them among the world's largest state armed forces. The U.S. Armed Forces has significant capabilities in both defense and power projection due to its large budget, resulting in advanced and powerful technologies which enable widespread deployment of the force globally, including around 800 military bases around the world.

History

The history of the U.S. Armed Forces dates back to 14 June 1775, with the creation of the Continental Army, even before the Declaration of Independence marked the establishment of the United States. The Continental Navy, established on 13 October 1775, and Continental Marines, established on 10 November 1775, were created in close succession by the Second Continental Congress in order to defend the new nation against the British Empire in the American Revolutionary War.

These forces demobilized in 1784 after the Treaty of Paris ended the Revolutionary War. The Congress of the Confederation created the current United States Army on 3 June 1784. The United States Congress created the current United States Navy on 27 March 1794 and the current United States Marine Corps on 11 July 1798. All three services trace their origins to their respective Continental predecessors.

The 1787 adoption of the Constitution gave Congress the power to "raise and support armies," to "provide and maintain a navy", and to "make rules for the government and regulation of the land and naval forces", as well as the power to declare war. The president of the United States is the United States Armed Forces' commander-in-chief.

The United States Coast Guard traces its origin to the formation of the Revenue Cutter Service on 4 August 1790, which merged with the United States Life-Saving Service on 28 January 1915 to establish the Coast Guard.

The United States Air Force was established as an independent service on 18 September 1947; it traces its origin to the formation of the Aeronautical Division, U.S. Signal Corps, which was formed 1 August 1907 and was part of the Army Air Forces before being recognized as an independent service in the National Security Act of 1947.

The United States Public Health Service Commissioned Corps was formerly considered to be a branch of the United States Armed Forces from 29 July 1945 until 3 July 1952, and is now one of the eight uniformed services of the United States. Should it be called into active duty again, it would constitute a seventh branch of the Armed Forces.

The United States Space Force was established as an independent service on 20 December 2019. It is the sixth branch of the U.S. military and the first new branch in 72 years. The origin of the Space Force can be traced back to the Air Force Space Command, which was formed 1 September 1982 and was a major command of the United States Air Force.

The U.S. Congressional Research Office annually publishes a List of Notable Deployments of U.S. Military Forces Overseas since 1798.

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