In 1943, Donald Michie, Alan Turing, and Jack Good were poised at the crossroads of AI. World War II, Hitler, German U-boats, and wartime code-breaking set the scene. Together they would take walks in the English countryside talking about various approaches, conjectures, and arguments concerning what today we call AI. They formed an intellectual cabal with a shared obsession with thinking machines and particularly with machine learning as the only credible road to achieving such machines. The breaking of the Naval Enigma code, which Turing worked on, and the building of Colossus, the first large electronic valve computer, which Michie and Good worked on, changed the war dramatically.