Benedict Arnold (14 January 1741 [O.S. 3 January 1740] June 14, 1801) was an American military officer who served during the Revolutionary War. He fought with distinction for the American Continental Army and rose to the rank of major general before defecting to the British side of the conflict in 1780. General George Washington had given him his fullest trust and had placed him in command of West Point in New York. Arnold was planning to surrender the fort there to British forces, but the plot was discovered in September 1780, whereupon he fled to the British lines. In the later part of the conflict, Arnold was commissioned as a brigadier general in the British Army, and placed in command of the American Legion. He led the British army in battle against the soldiers whom he had once commanded, after which his name became synonymous with treason and betrayal.Arnold was born in Connecticut. In 1775, when the war began, he was a merchant operating ships in the Atlantic Ocean. He joined the growing American army outside of Boston, and distinguished himself by acts that demonstrated intelligence and bravery: In 1775, he captured Fort Ticonderoga. In 1776, he deployed defensive and delay tactics at the Battle of Valcour Island in Lake Champlain that gave American forces time to prepare New York's defenses. His performance in the Battle of Ridgefield in Connecticut prompted his promotion to major general. He performed operations that provided the Americans with relief during the Siege of Fort Stanwix, and key actions during the pivotal 1777 Battles of Saratoga, in which he sustained leg injuries that put him out of combat career for several years.

Arnold repeatedly claimed that he was being passed over for promotion by the Continental Congress, and that other officers were being given credit for some of his accomplishments. Some among those in his military and political circles charged him with corruption and other bad acts. After formal inquiries, he was usually acquitted, but Congress investigated his finances and determined that he was indebted to Congress, and that he had borrowed money heavily to maintain a lavish lifestyle.

Arnold mingled with Loyalist sympathizers in Philadelphia and married into a Loyalist family when he wedded Peggy Shippen. She was a close friend of British major John Andr and kept in contact with him when he became head of the British espionage system in New York. Many historians see her as having facilitated Arnold's plans to switch sides; he opened secret negotiations with her friend Andr, and she relayed their messages to each other. The British promised £20,000 for the capture of West Point, a major American stronghold; Washington greatly admired Arnold and gave him command of that fort in July 1780. His scheme was to surrender the fort to the British, but it was exposed in September 1780 when revolution militia captured Andr carrying papers which revealed the plot. Arnold escaped; Andr was hanged.

Arnold received a commission as a brigadier general in the British Army, an annual pension of £360, and a lump sum of over £6,000. He led British forces in the Raid of Richmond and nearby areas, and they burned much of New London, Connecticut, to the ground and slaughtered surrendering forces after the Battle of Groton Heightsjust a few miles downriver from the town where he had grown up. In the winter of 1782, he and Peggy moved to London, England. He was well received by King George III and the Tories but frowned upon by the Whigs and most Army officers. In 1787, he moved to Canada to run a merchant business with his sons Richard and Henry. He was extremely unpopular there and returned to London permanently in 1791, where he died ten years later.

The American Revolutionary War (April 19, 1775 – September 3, 1783), also known as the Revolutionary War or American War of Independence, secured a United States of America independent from Great Britain. Fighting began on April 19, 1775, followed by the Declaration of Independence on July 4, 1776. The American Patriots were supported by France and Spain, conflict taking place in North America, the Caribbean, and Atlantic Ocean. It ended on September 3, 1783 when Britain accepted American independence in the Treaty of Paris, while the Treaties of Versailles resolved separate conflicts with France and Spain.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 in the Seven Years' War in 1763, tensions arose over trade, colonial policy in the Northwest Territory and taxation measures, including the Stamp Act and Townshend Acts. Colonial opposition led to the 1770 Boston Massacre and 1773 Boston Tea Party, with Parliament responding by imposing the so-called Intolerable Acts.

On September 5, 1774, the First Continental Congress drafted a Petition to the King and organized a boycott of British goods. Despite attempts to achieve a peaceful solution, fighting began with the Battle of Lexington on April 19, 1775 and in June Congress authorized George Washington to create a Continental Army. 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 to be 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.

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 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, ratified on September 3, 1783.