The Enigma of Ultra
Ultra was the codename used by the British authorities in the Second World War for intelligence obtained from the more important enemy cyphers. From the spring of 1941 they broke these cyphers to an unprecedented extent and with little delay. Their success has two explanations.
Firstly, as early as the 1920s they had concentrated all their cryptanalytical effort in one place – the Government Code and Cypher School which moved to Bletchley on the out- break of war. Secondly, at Bletchley, where the staff increased from about 120 in 1939 to nearly 7,000 by the beginning of 1944, men and women recruited mainly from the universities developed methods and machinery of a sophistication hitherto undreamt of, including the first operational electronic computer. Without these advances, at least the most difficult of the cyphers – those based on the German Enigma machine, and the still more complex systems used by Germany for non-morse transmissions – would have been for all practical purposes invulnerable.