The American Revolution (1765–1783) was an ideological and political movement in the Thirteen Colonies in what was then British America. The revolution culminated in the American Revolutionary War, which was launched on April 19, 1775, in the Battles of Lexington and Concord. Leaders of the American Revolution were colonial separatist leaders who, as British subjects, initially sought incremental levels of autonomy but came to embrace the cause of full independence and the necessity of prevailing in the Revolutionary War to obtain it. The Second Continental Congress, which represented the colonies and convened in present-day Independence Hall in Philadelphia, formed the Continental Army and appointed George Washington as its commander-in-chief in June 1775, and unanimously adopted the Declaration of Independence the following year, which inspired, formalized, and escalated the war. For most of the eight-year war, its outcome appeared uncertain. But in 1781, a decisive victory by Washington and the Continental Army in the Siege of Yorktown inspired King George III and the British to negotiate an end to colonial rule in the colonies and acknowledge their independence, which was codified in the Treaty of Paris in 1783, leading to the establishment of the sovereign United States of America.