Both the North and South adeptly gathered information important to their causes. The covert operations of civilian and military spy networks used the latest technology--disappearing ink, complex cyphers, codes, counter-intelligence, and propaganda--all while maintaining operational security. An invaluable tool in the game of espionage, the cypher wheel allowed both sides to carry on unending correspondence in secret code. Includes instructions on how to use cypher wheel. Approx 6 long.