This chapter can be summarized as Cryptanalysis helps elect a President. The president in question was James A. Garfield.
I have limited interest in the American Civil War, so few things were note-worthy in this chapter.
One minor exception: Multiple anagramming was introduced. This is the general technique of solving transposition ciphers when you have two or more cipher texts of the same length that use the same key. It’s a simple idea really: Because the same key is used, all the cipher texts have been transposed in the same manner. So if you find a solution for one, it must also be a solution for the rest.
Note: Don’t be that person suggesting a Caesar substitution cipher for military use in 1862 (see page 216)
