During the American War of Independence, which general switched allegiances and joined the British side?

Benedict Arnold (January 14, 1741 – June 14, 1801) was a general during the American Revolutionary War who originally fought for the American Continental Army but defected to the British Army. While a general on the American side, he obtained command of the fortifications at West Point, New York (future site of the U.S. Military Academy after 1802) overlooking the cliffs at the Hudson River (upriver from British-occupied New York City), and planned to surrender it to the British forces. The plan was exposed in September 1780, and he was commissioned into the British Army as a brigadier general. Arnold received an annual pension of £360, and a lump sum of over £6,000.

Arnold was born in Connecticut and was a merchant operating ships on the Atlantic Ocean when the war broke out in 1775. He joined the growing army outside Boston and distinguished himself through acts of intelligence and bravery. Despite Arnold's successes, he was passed over for promotion by the Continental Congress, while other officers claimed credit for some of his accomplishments.