By the time Benedict Arnold reached adulthood, family financial constraints had forced him to withdraw from school; yellow fever had killed three of his siblings and he'd become responsible for his father, a frequently incarcerated alcoholic who squandered the family's fortune.
Arnold managed to become an international merchant whose financial success was stymied by British-imposed tax acts. He fought back by joining the military group, the Sons of Liberty, at times using his own money to train and equip troops. Successful battles against the British gained him the admiration of George Washington and Thomas Jefferson, but also a permanently injured leg. With civilian leaders stinting on supplies for the army and popular support for the American Revolution declining, a disillusioned Arnold began to think his country might be better off under British rule.
He was appointed to run West Point, a key military position during the Revolutionary War. Arnold betrayed America by offering to sell plans of the fort, including the location of its armament stores and other war secrets, to the British for an amount that would equal $3 million today.
When the treasonous plot was intercepted in 1780, Arnold went from hero to zero. He was convicted of treason, and his name was erased from military records. Arnold began fighting for England and eventually moved to London. He spent the rest of his life trying to ingratiate himself with British trading companies and the British military. He was unsuccessful at both pursuits and died in 1801 [sources: Biography, Creighton].