With the invention of the telegraph and radio broadcast in the early 1900ly for military use. During World War II, the Germans used the ADFGVX cipher, which used matrix transposition to encrypt a message. A more secure method, called the Hill cipher, encrypted a plaintext message by matrix multiplication. Lester Hill also invented a mechanical machine to perform this operation, although it never sold. By the advent of World War II, the math behind cryptanalysis was much better understood, and the weaknesses of these methods were much clearer. The new math led directly to the introduction of rotor-based machines such as the Enigma for the Germans and the TeleX for the British.