While we often think of spies and spy networks as a 20th century innovation, the Civil War was filled with both. Men and women on both sides rallied to their respective cause, and volunteered to pass information to either the North or South. The Civil War also saw many innovations in spying, including the use of invisible ink, the use of advanced cryptography, and numerous women risking their lives to act as spies. Among the spies and spymasters covered are Belle Boyd, Jacob Thompson, Rose O'Neal Greenhow, James J. Andrews, Pauline Cushman, Colonel George H. Sharpe, Elizabeth Van Lew, General Grenville Dodge, Allen Pinkerton and Lafayette Baker. The book includes 19 photos.