The American Revolutionary War had its origins in the resistance of many Americans to taxes, which they claimed were unconstitutional, imposed by the British parliament. Patriot protests escalated into boycotts, and on December 16, 1773, the destruction of a shipment of tea at the Boston Tea Party. The British government punished Massachusetts by closing the port of Boston and taking away self-government. The Patriots responded by setting up a shadow government that took control of the province outside of Boston. Twelve other colonies supported Massachusetts, formed a Continental Congress to coordinate their resistance, and set up committees and conventions that effectively seized power from the royal governments. In April 1775 fighting broke out between Massachusetts militia units and British regulars at Lexington and Concord. The Continental Congress appointed General George Washington to take charge of militia units besieging British forces in Boston, forcing them to evacuate the city in March 1776. Congress supervised the war, giving Washington command of the new Continental Army; he also coordinated state militia units.
On July 2, 1776, the Continental Congress formally voted for independence, and issued its Declaration on July 4. The British were meanwhile mustering forces to suppress the revolt. Sir William Howe outmaneuvered and defeated Washington, capturing New York City and New Jersey. Washington was able to capture a Hessian detachment at Trenton and drive the British out of most of New Jersey. In 1777 Howe's army launched a campaign against the national capital at Philadelphia, failing to aid Clinton's separate invasion force from Canada. Clinton's army was trapped, and surrendered after the Battles of Saratoga in October 1777. A treaty was signed in 1779, granting American independence but began a long Cold War between the British Empire and America.