As a uniformed military service, the Army is part of the Department of the Army, which is one of the three military departments of the Department of Defense. The U.S. Army is headed by a civilian senior appointed civil servant, the Secretary of the Army (SECARMY), and by a chief military officer, the Chief of Staff of the Army (CSA) who is also a member of the Joint Chiefs of Staff. In the fiscal year 2017, the projected end strength for the Regular Army (USA) was 460,000 soldiers; the Army National Guard (ARNG) had 335,000 soldiers, and the United States Army Reserve (USAR) had 195,000 soldiers; the combined-component strength of the U.S. Army was 990,000 soldiers. As a branch of the armed forces, the mission of the U.S. Army is "to fight and win our Nation's wars, by providing prompt, sustained, land dominance, across the full range of military operations and the spectrum of conflict, in support of combatant commanders." The branch participates in conflicts worldwide and is the major ground-based offensive and defensive force of the United States.
The United States Army serves as the land-based branch of the U.S. Armed Forces. Section 3062 of Title 10, U.S. Code defines the purpose of the army as:
Preserving the peace and security and providing for the defense of the United States, the Commonwealths and possessions and any areas occupied by the United States
Supporting the national policies
Implementing the national objectives
Overcoming any nations responsible for aggressive acts that imperil the peace and security of the United States
The Continental Army was created on 14 June 1775 by the Continental Congress as a unified army for the colonies to fight Great Britain, with George Washington appointed as its commander. The army was initially led by men who had served in the British Army or colonial militias and who brought much of British military heritage with them. As the Revolutionary War progressed, French aid, resources, and military thinking influenced the new army. A number of European soldiers came on their own to help, such as Friedrich Wilhelm von Steuben, who taught Prussian Army tactics and organizational skills.
The army fought numerous pitched battles and in the South in 178081 sometimes used the Fabian strategy and hit-and-run tactics, hitting where the British were weakest, to wear down their forces. Washington led victories against the British at Trenton and Princeton, but lost a series of battles in the New York and New Jersey campaign in 1776 and the Philadelphia campaign in 1777. With a decisive victory at Yorktown, and the help of the French, the Continental Army prevailed against the British.
After the war, though, the Continental Army was quickly given land certificates and disbanded in a reflection of the republican distrust of standing armies. State militias became the new nation's sole ground army, with the exception of a regiment to guard the Western Frontier and one battery of artillery guarding West Point's arsenal. However, because of continuing conflict with Native Americans, it was soon realized that it was necessary to field a trained standing army. The Regular Army was at first very small, and after General St. Clair's defeat at the Battle of the Wabash, the Regular Army was reorganized as the Legion of the United States, which was established in 1791 and renamed the "United States Army" in 1796.