Developed by engineer Arthur Scherbius in the 1920s and used by the Nazis throughout WWII, the Enigma machine used multiple electric rotors to create the most complex code the world had ever seen. But the Allies famously cracked the Enigma fairly early on in the war, thanks to brilliant and tireless codebreaking work at Bletchley Park in England, and referred to intelligence gathered from Enigma-encoded transmissions by an equally cool code name: Ultra.