Benedict Arnold (Brandt (1994), p. 4June 14, 1801) was an American-born British military officer who served during the American Revolutionary War. He fought with distinction for the American Continental Army and rose to the rank of major general before defecting to the British 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 to British forces, but the plot was discovered in September 1780, whereupon he fled to the British lines. In the later part of the war, Arnold was commissioned as a brigadier general in the British Army and placed in command of the American Legion. He led British forces in battle against the army which he had once commanded, and his name became synonymous with treason and betrayal in the United States.Rogets (2008)

Born in Connecticut, Arnold was a merchant operating ships in the Atlantic when the war began. 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 employed defensive and delaying tactics at the Battle of Valcour Island on 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 conducted 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 for several years.

Arnold repeatedly claimed that he was being passed over for promotion by the Second Continental Congress, and that other officers were being given credit for some of his accomplishments.Martin (1997) Some in his military and political circles charged him with corruption. After formal inquiries, he was acquitted of all but two minor charges, 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 the Loyalist family of Peggy Shippen. She was a close friend of British Major John André 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 André, 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. Arnold planned to surrender the fort to the British, but it was exposed in September 1780 when American militiamen captured André carrying papers which revealed the plot. Arnold escaped, and André 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 on Richmond and oversaw a raid on New London, Connecticut, which burned much of it to the ground. Arnold also commanded British forces at the Battle of Blandford and the Battle of Groton Heights, the latter taking place just a few miles downriver from the town where he had grown up. In the winter of 1782, he and Shippen moved to London. He was well received by King George III and the Tories but frowned upon by the Whigs and most British Army officers. In 1787, he moved to the colony of New Brunswick in what is now 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.

Early life Benedict Arnold was born the second of six children of his father Benedict Arnold III (1683–1761) and Hannah Waterman King in Norwich, Connecticut Colony, on January 14, 1741.Murphy (2007), pp. 5, 8 Arnold was the fourth member of his family named after his great-grandfather Benedict Arnold I, an early governor of the Colony of Rhode Island; his grandfather (Benedict Arnold II) and father, as well as an older brother who died in infancy, were also named for the colonial governor. Only he and his sister Hannah survived to adulthood; his other siblings died from yellow fever in childhood.Brandt (1994), pp. 5–6 Arnold's siblings were, in order of birth: Benedict (1738–1739), Hannah (1742–1803), Mary (1745–1753), Absolom (1747–1750) and Elizabeth (1749–1755). Through his maternal grandmother, Arnold was a descendant of John Lothropp, an ancestor of six presidents.Price (1984), pp. 38–39

Arnold's father was a successful businessman, and the family moved in the upper levels of Norwich society. He was enrolled in a private school in nearby Canterbury when he was aged 10, with the expectation that he would eventually attend Yale College. However, the deaths of his siblings two years later may have contributed to a decline in the family's fortunes, since his father took up drinking. By the time Arnold was 14, there was no money for private education. His father's alcoholism and ill health kept him from training Arnold in the family mercantile business, but his mother's family connections secured an apprenticeship for him with her cousins Daniel and Joshua Lathrop, who operated a successful apothecary and general merchandise trade in Norwich.Brandt (1994), p. 6 His apprenticeship with the Lathrops lasted seven years.Brandt (1994), p. 7

Arnold was very close to his mother, who died in 1759. His father's alcoholism worsened after her death, and the youth took on the responsibility of supporting his father and younger sister. The elder Arnold was arrested on several occasions for public drunkenness, was refused communion by his church, and died in 1761.

French and Indian War In 1755, Arnold was attracted by the sound of a drummer and attempted to enlist in the Connecticut provincial militia for service in the French and Indian War (known in Canada as a part of the more global Seven Years' War), but his mother refused permission.Flexner (1953), p. 7 In 1757, when he was aged 16, Arnold did enlist in the Connecticut militia, which marched off toward Albany, New York, and Lake George. The French had besieged Fort William Henry in northeastern New York, and their Indian allies had committed atrocities after their victory. Word of the siege's disastrous outcome led the company to turn around, and Arnold served for only thirteen days.Flexner (1953), p. 8 A commonly accepted story that he deserted from militia service in 1758Randall (1990), p. 32 is based on uncertain documentary evidence.Murphy (2007), p. 18

Colonial merchant Arnold established himself in business in 1762 as a pharmacist and bookseller in New Haven, Connecticut, with the help of the Lathrops.Brandt (1994), p. 8 He was hardworking and successful, and was able to rapidly expand his business. In 1763, he repaid money that he had borrowed from the Lathrops,Brandt (1994) p. 10 repurchased the family homestead that his father had sold when deeply in debt, and resold it a year later for a substantial profit. In 1764, he formed a partnership with Adam Babcock, another young New Haven merchant. They bought three trading ships, using the profits from the sale of their homestead, and established a lucrative West Indies trade.

During this time, Arnold brought his sister Hannah to New Haven and established her in his apothecary to manage the business in his absence. He traveled extensively in the course of his business throughout New England and from Quebec to the West Indies, often in command of one of his own ships.Flexner (1953), p. 13 Some sources allege that on one of his voyages he fought a duel in Honduras with a British sea captain who had called him a "damned Yankee, destitute of good manners or those of a gentleman."Murphy (2007), p. 38Roth (1995), p. 75 The captain was wounded in the first exchange of gunfire, and he apologized when Arnold threatened to aim to kill on the second.Flexner (1953), p. 17 However, it is unknown whether this encounter actually happened or not, and some historians characterize the alleged duel as a fabrication.

The Sugar Act 1764 and the Stamp Act 1765 severely curtailed mercantile trade in the colonies.Randall (1990), p. 46 The Stamp Act prompted Arnold to join the chorus of voices in opposition, and also led to his joining the Sons of Liberty, a secret organization which advocated resistance to those and other restrictive Parliamentary measures.Randall (1990), p. 49 Arnold initially took no part in any public demonstrations but, like many merchants, continued to do business openly in defiance of the acts, which legally amounted to smuggling. He also faced financial ruin, falling £16,000 () in debt with creditors spreading rumors of his insolvency, to the point where he took legal action against them.Randall (1990), pp. 52–53 On the night of January 28, 1767, Arnold and members of his crew roughed up a man suspected of attempting to inform authorities of their smuggling. He was convicted of disorderly conduct and fined the relatively small amount of 50 shillings; publicity of the case and widespread sympathy for his views probably contributed to the light sentence.Randall (1990), pp. 56–60

On February 22, 1767, Arnold married Margaret Mansfield, daughter of Samuel Mansfield, the sheriff of New Haven and a fellow member in the local Masonic lodge. Their son Benedict was born the following yearBrandt (1994), p. 14 and was followed by brothers Richard in 1769 and Henry in 1772.Randall (1990), p. 62 Margaret died on June 19, 1775, while Arnold was at Fort Ticonderoga following its capture.Brandt (1994), p. 38 She is buried in the crypt of the Center Church on New Haven Green. The household was dominated by Arnold's sister Hannah, even while Margaret was alive. Arnold benefited from his relationship with Mansfield, who became a partner in his business and used his position as sheriff to shield him from creditors.Randall (1990), p. 64

Arnold was in the West Indies when the Boston Massacre took place on March 5, 1770. He wrote that he was "very much shocked" and wondered, "Good God, are the Americans all asleep and tamely giving up their liberties, or are they all turned philosophers, that they don't take immediate vengeance on such miscreants?"Randall (1990), p. 68

Revolutionary War (American service)

Siege of Boston and Fort Ticonderoga

Arnold began the war as a captain in the Connecticut militia, a position to which he was elected in March 1775. His company marched northeast the following month to assist in the Siege of Boston that followed the Battles of Lexington and Concord. He proposed an action to the Massachusetts Committee of Safety to seize Fort Ticonderoga in upstate New York, which he knew was poorly defended. They issued him a colonel's commission on May 3, 1775, and he immediately rode off to Castleton in the disputed New Hampshire Grants (Vermont) in time to participate with Ethan Allen and his men in the capture of Fort Ticonderoga. He followed up that action with a bold raid on Fort Saint-Jean on the Richelieu River north of Lake Champlain. A Connecticut militia force arrived at Ticonderoga in June; Arnold had a dispute with its commander over control of the fort and resigned his Massachusetts commission. He was on his way home from Ticonderoga when he learned that his wife had died earlier in June.Randall (1990), pp. 78–132

Quebec expedition