What was ultra during World War 2?

Answer 1

Ultra was the Allied name for Enigma, a German ciphering machine which looked something like a typewriter. Since the Enigma code changed every day, it was impossible to break, but the Allies captured an Enigma machine early in the war and were able to decipher the German code. At first, Ultra would seem to have been an easy end to the war, but it was important to keep Germany believing that their code had not been broken, lest they switch to a different coding system. Therefore, some information from Ultra was acted upon by the Allies, and some was not, so that Nazi Germany would remain convinced that their encoding system was intact.