Overview
The Continental Congress in 1775 created the Continental Army and named General George Washington its commander. This newly formed army, along with state militia forces, and the French army and navy, defeated the British in 1781. The new Constitution in 1789 made the president the commander in chief, with authority for the Congress to levy taxes, and make the rules.
As of 2012, the U.S. military consists of an Army, Navy, Air Force and Marine Corps under the command of the United States Department of Defense. There also is the United States Coast Guard, which is controlled by the Department of Homeland Security.
The President of the United States is the commander in chief, and exercises the authority through the Secretary of Defense and the Chairman of the Joint Chiefs of Staff, which supervises combat operations. In addition, each state has a national guard commanded by the state's governor and coordinated by the National Guard Bureau. The President of the United States has the authority during national emergencies to assume control of individual state National Guard units.
Read more about this topic: Military History Of The United States