Why was the Colossus computer built? (unknown pages of the history of computer science)

In the article is described the use of the 1st world computer Colossus for the breaking of the ciphers of supreme German command, including Hitler. The unique Memoirs of the codebraker, who worked during the years of war in the center of decoding in the Bletchley Park, served as source. In view of the absolute secrecy of project in time of 60 years, Memoirs were written after project declassification in the early 2000s. Memoirs were published after author death.