The American Revolutionary War (April 19, 1775 – September 3, 1783), also known as the Revolutionary War or American War of Independence, secured American independence from Great Britain. Fighting began on April 19, 1775, followed by the Lee Resolution on July 2, 1776, and the Declaration of Independence on July 4, 1776. The American Patriots were supported by the Kingdom of France and, to a lesser extent, the Dutch Republic and the Spanish Empire, in a conflict taking place in North America, the Caribbean, and the Atlantic Ocean.

Established by royal charter in the 17th and 18th centuries, the American colonies were largely autonomous in domestic affairs and commercially prosperous, trading with Britain and its Caribbean colonies, as well as other European powers via their Caribbean entrepôts. After British victory over the French in the Seven Years' War in 1763, tensions between the motherland and her 13 colonies arose over trade, policy in the Northwest Territory, and taxation measures, including the Stamp Act and Townshend Acts. Colonial opposition led to the Boston Massacre in 1770 which largely fostered the idea of independence from Britain. While the earlier taxation measures were repealed, Parliament adopted the Tea Act in 1773, a measure that led to the Boston Tea Party on December 16. In response, Parliament imposed the so-called Intolerable Acts in mid-1774, closing the Boston Harbor, revoking Massachusetts' charter, and placing the colony under control of the British government.

The measures stirred unrest throughout the colonies, 12 of which sent delegates to Philadelphia in early September 1774 to organize a protest as the First Continental Congress. In an appeal to Britain's George III seeking peace, the Congress drafted a Petition to the King but also threatened a boycott of British goods known as the Continental Association if the Intolerable Acts were not withdrawn. Despite attempts to achieve a peaceful solution, fighting began, after the Westminster Massacre in March, with the Battle of Lexington on April 19, 1775, and in June Congress authorized the creation of a Continental Army with George Washington as commander-in-chief. Although the "coercion policy" advocated by the North ministry was opposed by a faction within Parliament, both sides increasingly viewed conflict as inevitable. The Olive Branch Petition sent by Congress to George III in July 1775 was rejected, and in August Parliament declared the colonies in a state of rebellion.

Following the loss of Boston in March 1776, Sir William Howe, the new British commander-in-chief, launched the New York and New Jersey campaign. He captured New York City in November, before Washington won small but significant victories at Trenton and Princeton, which restored Patriot confidence. In summer 1777, Howe succeeded in taking Philadelphia, but in October a separate force under John Burgoyne was forced to surrender at Saratoga. This victory was crucial in convincing powers like France and Spain an independent United States was a viable entity. The Continental Army then went into winter quarters in Valley Forge, where General von Steuben drilled it into an organized fighting unit.

France provided the US informal economic and military support from the beginning of the rebellion, and after Saratoga the two countries signed a commercial agreement and a Treaty of Alliance in February 1778. In return for a guarantee of independence, Congress joined France in its global war with Britain and agreed to defend the French West Indies. Spain also allied with France against Britain in the Treaty of Aranjuez (1779), though it did not formally ally with the Americans. Nevertheless, access to ports in Spanish Louisiana allowed the Patriots to import arms and supplies, while the Spanish Gulf Coast campaign deprived the Royal Navy of key bases in the south.

This undermined the 1778 strategy devised by Howe's replacement, Sir Henry Clinton, which took the war into the Southern United States. Despite some initial success, by September 1781 Cornwallis was besieged by a Franco-American force in Yorktown. After an attempt to resupply the garrison failed, Cornwallis surrendered in October, and although the British wars with France and Spain continued for another two years, this largely ended fighting in North America. In April 1782, the North ministry was replaced by a new British government which accepted American independence and began negotiating the Treaty of Paris. With the treaty's ratification on September 3, 1783, Britain accepted American independence, and the war officially ended. The Treaties of Versailles resolved separate conflicts with France and Spain.