George Washington Warns West Point Prepare for Attack Due to Arnold's Treason, September 27, 1780

In 1780, near the present-day Tappan Zee Bridge, a major spy drama unfolded, changing the course of the American Revolution. Major General Benedict Arnold secretly attempted to help the British capture the fort at West Point. He had grown resentful of the American Army for not rewarding him for his many military victories. On the night of September 21, Arnold gave British Major John André documents detailing the fortifications and troop strengths at West Point. As André headed towards the British lines with the documents tucked in his boot he was captured near Tarrytown on September 23. If he had reached the British command in New York City with the information Arnold had given them, the British would likely have taken the fort at West Point. West Point was crucial to controlling the Hudson River, so a British capture could have changed the outcome of the entire war.
Thirty-year-old André was hanged as a spy on October 2, 1780. Benedict Arnold escaped to New York City, eventually commanding British troops for the remainder of the American Revolution. He died in London in 1801.

Who was Benedict Arnold and what role did he play in the Revolutionary War?