In 1943 with the greatest of secrecy, the Collossus, the world's first digital electronic computer, was built at Bletchley Park in England to crack the Lorenz, the equally secret code machine of the German High Command.  In the first of three sessions, we will look at the invention and inner workings of the forerunner of the Lorenz, the Enigma, and how it was initially broken by the Poles before the start of the war.  Next, we will follow throughout the war the cat and mouse game between German Enigma codemakers and British and American Enigma codebreakers.  Finally, we will look at the Lorenz, the Collossus, and the aftermath for the Allied c odebreaking community.