They had access to quite interesting cryptography tools as well, such as a cipher disks : https://en.wikipedia.org/wiki/Cipher_disk https://en.wikipedia.org/wik

They had access to quite interesting cryptography tools as well, such as a cipher disks : https://en.wikipedia.org/wiki/Cipher_disk https://en.wikipedia.org/wiki/Cipher_disk And see : http://slclip.wikispaces.com/Cryptology+during+the+US+war+of+independence+and+the+US+civil+war http://slclip.wikispaces.com/Cryptology+during+the+US+war+of... There's an interesting article by Lee Taylor on civil war codes and encryption too http://chesapeakesignals.com/encrypt.htm http://chesapeakesignals.com/encrypt.htm