George Washington, Spymaster: How the Americans Outspied the British and Won the Revolutionary War
Ok, the title is lengthy, but it's a great book. Even if you aren't American and probably don't care, it's cool for what it is. If you enjoy codes, ciphers, espionage- that kind of thing (like moi) it's also really good for that.
I've snuck this into my language arts class...we're supposed to be reading biographies, but...I guess it could be classified as one, right?