Benedict Arnold, an American officer in the Revolutionary War who deserted to the British, was born in norwich, Connecticut on January 14, 1741. His family had been a distinguished one in Rhode Island. In the fall of 1757 he served with the militia in the French and Indian War, but soon returned home and completed his apprenticeship with a firm of druggists. In 1762 he opened a drug and book store in New Haven. As the store prospered, Arnold bought ships and engaged in trade with Canada and the West Indies.

Late in 1774 he was elected captain of a militia company. When news of the outbreak of hostilities at Lexington arrived in April 1775, Arnold marched his company to Cambridge and immediately proposed the capture of Fort Ticonderoga and seizure of its cannon. Named a colonel by Massachusetts on May 3, 1775, he was authorized to raise a regiment and proceed with his plan. But he soon found himself forestalled by Ethan Allen, who had been authorized by Connecticut to undertake the same mission and had already recruited a force. Reluctantly waiving his own claim to command, Arnold joined Allen as a volunteer in the successful attack. He then seized a ship and with a hundred men ran down Lake Champlain and captured St. John's.

When Arnold returned to Cambridge, Washington gave him command of an expedition to Quebec via the Maine wilderness. The march of 700 men was a remarkable feat of woodsmanship and endurance, but Quebec was too strong to be attacked until Arnold was joined by General Richard Montgomery's force from Montreal. The combined assault in a snowstorm on December 31, 1775, failed; Montgomery was killed, and Arnold severely wounded. Congress promoted him to the rank of brigadier general, and he continued to besiege the city until spring when he was forced to retreat to Montreal and Lake Champlain. Enlarged British forces followed, intent on reaching Albany. Arnold constructed a flotilla on Lake Champlain and inflicted severe losses on a greatly superior enemy fleet near Valcour Island, October 11, 1776. He returned home a hero, but his rash courage and impatient energy had aroused the enmity of several other officers. When in February 1777 congress created five new major generals, Arnold, the ranking brigadier, was passed over in favor his juniors because of the political necessity of apportionment among the states. Only Washington's personal persuasion kept Arnold from resigning.

Two months later, while he was at New Haven, Danbury was attacked. Arnold took immediate action and drove the British back to their ships. This exploit forced congress to make him a major general but his seniority was not restored, and Arnold felt his honor impugned. He tried to resign but accepted congress' order in July to join General Philip Schuyler above Albany to stem a fresh invasion from Canada under Bristish General John Burgoyne. He marched up the Mohawk valley in August against Colonel St. Leger and raised the siege of Fort Stanwix (now Rome, NY). Arnold later commanded the left wing in the first Battle of Saratoga on September 19, 1777. In the second battle of October 7, he galloped into action, took command of advance battalions, and fought brilliantly and decisively until seriously wounded. For his services he received a new commission restoring him to his proper relative rank.

Since Arnold's wounds had left him crippled, Washington placed him in command of Philadelphia in June 1778. He enjoyed the city's social life, moved among families of loyalist sympathies, and lived extravagantly. To make money he violated several state and military regulations, arousing the suspicions and finally the denunciations of Pennsylvania's supreme executive council. The charges against him were then referred to congress. Some of the charges were thrown out, but four remained and Arnold asked for a speedy court-martial to clear himself. Meanwhile, on April 8, 1779, four years after the death of his first wife, he married young Margaret (Peggy) Shippen (1760-1804), duaghter of a moderate loyalist. She had been impressed by the society of British officers during the previous winter of occupation and was loyalist in feeling. Either she suggested that they change sides or readily seconded such a suggestion from Arnold, for early in May he made secret overtures to British headquarters. He was asked to remain on the American side and send information until he obtained an important post of field command that he could betray. Payment was promised, but the British were vague about the amount, to Arnold's irritation. He did forward intelligence from time to time and persisted in asking £10,000 for indemnification plus the rank of major general in the British army for his services. The correspondence lapsed in October 1779.

Arnold's postponed trial finally was held in December 1779, and he was found guilty of two minor offenses and sentenced to a reprimand by Washington. Mild and just as the sentence was, Arnold was furiously aggrieved. He reopened the treasonable correspondence in May 1780, sending news of the proposed invasion of Canada and later revealing that he expected to obtain the command of West Point. Having now an important fort to deliver, he asked £20,000 for betraying it, and half that sum if he failed and fled to the British lines. Major John André arranged to meet him on September 21 under a misuse of a flag of truce. As the ship that brought André up the Hudson was fired upon and forced to retire, André spent the night within American lines. The next day he was persuaded to don civilian disguise in order to return overland to New York, provided with a pass by Arnold. Suspicious American militiamen stopped and searched André on the morning of September 23 and found papers about the betrayal of West Point in his boot. Innocently, word of the capture of a possible spy was relayed to the fort. When notified of André's capture, Arnold managed to escape on the boat that had returned for André, leaving André to be hanged as a spy. Arnold's wife joined him later in New York.

The sacrifice of André made Arnold odious in New York, but General Clinton named him a provincial brigadier general, awarded him £6,000 plus expenses, and authorized him to raise a regiment of American deserters. Only 28 privates responded to his published appeals. Obtaining other voluteers from within the British ranks, he was sent on a raiding expedition to Virginia and captured Richmond, and in September 1781 led a raid on New London, Connecticut.

Upon Cornwallis' surrender, Arnold obtained permission to go to England and sailed on December 15, 1781. Naïvely he hoped to succeed Clinton as commander-in-chief, but the Tory ministry fell; peace was negotiated; and Arnold became a retired colonel on half pay. His wife was given a pension of £500 a year "for her services"; each of his sons was given a military commission and drew pay although too young to serve. Later the younger children were given pensions of £100.

Disappointed at the failure of his plans and embittered by the neglect and scorn he met in England, Arnold spent the years 1787-1791 at Saint John, N.B., once more engaging in the West India trade. But he was greatly disliked in Canada and in 1792 returned to London. He failed to get a command in the war with France and fought a duel with an earl who insulted him. Going to the West Indies again to trade, he was captured by the French but escaped. In business he steadily lost money. Back home and inactive, ostracized and ailing, he died on June 14, 1801. His wife survived him only three years.