The Colossus computer was a machine used by the British intelligence ser v ice during World War II to analyse and decr y pt telepr inter orders and messages enciphered with a Loren z SZ40/4 2 encr y ption machine by the Nazi Germany High Command. The contents of the messages were of incred ible value to the Allies, as they of ten contained key orders for German generals, including t roop movements and tactics.