John André
In September 1779, André got on a ship and sailed up the Hudson.  He met Arnold, who gave him papers and the plans to West Point.  But André could not get back to his ship because American forces had attacked it, and it had sailed away.  André decided to go back to British territory in disguise.  He took off his British army uniform and put on ordinary clothes.  On the way, he was captured by American freelance soldiers.  They found the papers Arnold had given André.  They arrested André as a spy.