16th August 2013. Can You Keep a Secret?
Bletchley’s code-breakers were summoned to duty, under the code-name ‘Captain Ridley’s shooting party’. All were sworn to a secrecy which they took to the grave, and only of recent years, via TV and obituaries, has information come out. As a result no official honours were given.
Bletchley was set up to break Enigma, (not a code), but complex machine systems, named for some reason after various ‘fish’, and used by the Germans in World War II, to encipher messages.
In the early days, the vast majority of messages were by ‘land-line’, but as the German extended their operations, radio was increasingly used, which needed the de-coding skills of the likes of Alan Turing and his Cambridge tutor Max Newman.
They were backed by the brilliant minds of Dillwyn Knox, Richard Pendered, Harry Hinsley, Alec Dakin, John Herivel, Gordon Welchman, Tommy Flowers the GPO engineer, who devised Colossus, the first electronic computer, and David Rees who died Today in 2013.
Professor Rees (1) was one of the last survivors of the Bletchley Code-Breakers, concerned with breaking the Red Code, one higher than the Yellow previously used in Norway It was used by the Luftwaffe, in January 1940 for ground liaison, when invasion of Belgium, Netherlands and France was imminent.
One notable at Bletchley, was the Cambridge mathematician John Herivel, who moved from Hut 6 to the ‘Newmanry’ the Max Newman section, where he worked with Turing in developing a scheme to break the code by hand, known as the ‘Herivel Tip’ (clusters of letters).
It was a cat and mouse exercise with both sides attempting to keep ahead of the game. So in the second half of 1941, the Germans added a new rotor to their Naval Enigma.
Thus it was nearly a year before vital signals were to become readable again by our cryptanalysts: all the time our shipping losses rose.
At the beginning of February 1942, the ‘shark’ a 4-rotor Enigma, used by U-boats, became unbreakable to October 1942, leaving Hut 8 helpless, (the ‘shark’ blackout): 43 allied ships were sunk in August and September.
However luck was on our side, in October 1942, when two ‘short-signal’ codebooks were captured from a U-boat by the destroyer HMS Petard’ off Egypt, helping decryption for several weeks, a great weapon against the U-boats menace.
W.T. Tutte helped to break the Fish or ‘Tunny’ (the first non-Morse -Code link), when he deduced the structure of the Lorenz SZ 40/42 teleprinter cipher machine. It was Newman who devised the idea of a computer to break the 2nd row of wheels on these machines. These ciphers provided conversations between Hitler and his generals in France and Italy, and yielded vital pre-D-Day intelligence.(2)
By 1943 codes were so complicated that some kind of a computer was thought necessary, as against pure handwork, for deciphering, and Rees transferred to ‘Newmanry’, where Colossus, the first electronic computer, was developed by Tommy Flowers of the Post Office, to break the new Lorenz systems.
(1) Daily Telegraph Obituary 20th August 2013. Rees died at 95: (29.5.1918-16.8.2013). It was said that he in fact broke the Red Code, but he was later hazy about the truth of the matter. Rees in later life was concerned with semi-group theory and commutative algebra, used in computer theory.
(2) This Section which broke the Abwehr Code, was run by Dillwyn (Dilly) Knox. The Double Cross Committee which ran the captured the German Agents managed to fool them about D-Day and Brigadier ‘Bill’ Williams Monty’s Chief Intelligence Officer said without the breaking of the Abwehr’s Enigma codes, we could never have known whether the deception had worked.
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