One of the most amazing things about everything the Culper Ring did is that this was -- obviously -- before telephones (let alone cell phones!), computers, even radio. And, the CIA still uses some of the practices George Washington and his spies used during the Revolutionary War.
You can listen to my conversation with Fox News Channel's Brian Kilmeade by going to http://www.wesb.com/listen/, clicking on "Local Programs" and scrolling down to #9. Listen until the end and Brian will tell you how to get a signed copy of the book.