John André
In 1776, André was sent back to the British army.  He was traded for American prisoners.  He wrote a book about everything he had learned about the British Colonies and drew maps of places he had been.  He gave the book to British General William Howe in New York City.  Howe thought the book was very good and that André was very intelligent.  He promoted André to captain and made him aide to Major-General Charles Grey.