Doing some research on spies and intelligence during the American Civil War for a book I'm writing. Any recommendations on where I can start? Biographies of famous spies? How intelligence worked in this time frame, etc.?
Southern Maryland was a hotbed of confederate spies, including the Chief Agent of the Confederate Secret Service in Maryland, Thomas Austin Jones. His house, "Huckleberry," is preserved in Popes Creek. He was the major conduit for Confederate incoming and outgoing mail, delivered by boat via Jones, who then mailed outgoing correspondence to foreign countries and agents operating in the Union, at the Bryantown post office. He picked up newspapers from NY, Philadelphia, Washington etc, as well as incoming mail for Richmond, and delivered that by boat across the Potomac. https://www.thebaynet.com/articles/0916/did-you-know-southern-maryland-was-once-a-hotbed-of-spies.html https://www.findagrave.com/memorial/9188182/thomas-austin-jones
Look at Harry Turtledove's alternate history series of the great war. He does have a few spies scattered in his books. The series is lengthy, I think 8 or 9 books but interesting.
I believe Harriet Tubman was a spy as well, if you want to look her up. Also, not your era I realise, but there is some information on Culpeper Ring out there, which was from the Revolutionary War. A century prior, but tips and tricks were probably relatively similar. Espionage didn't change vastly until the 20th C. I am also writing a novel about spies, but mine is in the 18th C (Seven Years War and I might add the Pontiac War) so any tips and good sources please send my way! ~Kae