The American Revolution was a political upheaval that took place between 1765 and 1783 during which rebel colonists in the Thirteen American Colonies rejected the British monarchy and aristocracy, overthrew the authority of Great Britain, and founded the United States of America.

Starting in 1765, members of American colonial society rejected the authority of the British Parliament to tax them. During the following decade protests by rebellious colonists - known as patriots - continued to escalate, as in the Boston Tea Party of 1773 and the British responded by imposing punitive laws—the Coercive Acts—on Massachusetts in 1774. Patriots in the other colonies rallied behind Massachusetts and in late 1774 they set up a Congress to better coordinate their resistance efforts against Britain, while other colonists, known as loyalists preferred to remain subjects of the British Crown.

The Patriots fought the British and loyalists in the American Revolutionary War (1775–1783). Formal acts of rebellion against British authority began in 1774 when the Patriot Suffolk Resolves effectively replaced the royal government of Massachusetts, and confined British control to the city of Boston. Tensions escalated to the outbreak of fighting between Patriot militia and British regulars at Lexington and Concord in April 1775. As the conflict evolved into a civil war, Patriots in each of the thirteen colonies formed a Provincial Congress that usurped power from the old colonial governments and suppressed loyalism. Claiming King George III's rule was tyrannical and violated the rights of Englishmen, the Continental Congress declared the colonies free and independent states in July 1776. These thirteen states became known as the United States of America, a loose confederacy under the 1777 Articles of Confederation. The Patriot leadership professed the political philosophies of liberalism and republicanism to reject monarchy and aristocracy, and proclaimed that all men are created equal. Congress rejected British proposals for compromise that would keep them under the king.

The British were forced out of Boston in 1776, but then captured and held New York City for the duration of the war, nearly capturing General Washington and his army. The British blockaded the ports and captured other cities for brief periods, but failed to defeat Washington's forces. In early 1778, following a failed patriot invasion of Canada, a British army was captured by a patriot army at the Battle of Saratoga, following which the French entered the war as allies of the United States. The naval and military power of the two sides were about equal, and France had allies in the Netherlands and Spain, while Britain had no major allies in this large-scale war. The war later turned to the American South, where the British captured an army at South Carolina, but failed to enlist enough volunteers from Loyalist civilians to take effective control. A combined American–French force captured a second British army at Yorktown in 1781, effectively ending the war in the United States. A peace treaty in 1783 confirmed the new nation's complete separation from the British Empire. The United States took possession of nearly all the territory east of the Mississippi River and south of the Great Lakes, with the British retaining control of Canada and Spain taking Florida. Among the significant results of the revolution was the creation of a democratically-elected representative government responsible to the will of the people.

In the period after the peace treaty in 1783, Loyalists were subjected to extreme suppression and acts of arbitrary violence, including murder by lynching, despite a promise by patriot leaders that their rights would be respected. A large proportion were driven off their land and forced to flee as refugees to Canada. The postwar period involved debates between nationally-minded men like Washington who wanted a strong national government, and leaders who wanted strong states but a weak national government. The former group won out in the ratification of a new United States Constitution in 1788. It replaced the weaker Articles of Confederation and Perpetual Union. The new Constitution established a relatively strong federal national government that included a strong elected president, national courts, a bicameral Congress that represented both states in the Senate and population in the House of Representatives. Congress had powers of taxation that were lacking under the old Articles. The United States Bill of Rights of 1791 comprised the first ten amendments to the Constitution, guaranteeing many "natural rights" that were influential in justifying the revolution, and attempted to balance a strong national government with strong state governments and broad personal liberties. The American shift to liberal republicanism, and the gradually increasing democracy, caused an upheaval of traditional social hierarchy and gave birth to the ethic that has formed a core of political values in the United States.

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