Topic - Ultra

Ultra was the designation adopted by British military intelligence in June 1941 for wartime signals intelligence obtained by breaking high-level encrypted enemy radio and teleprinter communications at the Government Code and Cypher School (GC&CS) at Bletchley Park. Several other cryptonyms had been used for such intelligence. British intelligence first designated it Boniface — presumably to imply that it was the result of human intelligence. The U.S. used the codename Magic for its decrypts from Japanese sources. - Source: Wikipedia