After the Treaty of Versailles, the German defense establishment wanted to improve its communication systems. Dr. Arthur Scherbius developed his first 'Enigma' machine. Within only three years, the German navy was already making its own version of this machine. The machine would let the operator type in a message into the machine, and then it would scramble it into a secret code. The reciever on the other side would have to know this secret code to understand the message. Over many years, this became more and more complicated, as German code experts added more plugs with electronic circuits. One of the most famous incidents that included this machine was probably the Zimmerman Telegram. The Zimmerman Telegram was a 1917 diplomatic proposal from Germany to Mexico. It was a proposal to make war against the United States. British Intelligence intercepted and decoded this proposal. Mainstream America became angry, and this helped generate support for the United States to declare war on Germany.