Talk Report 2018-04-04

Report on Mark Baldwin’s talk on The Enigma Machine, Bletchley Park and the Battle of the Atlantic.

Dr. Mark Baldwin is a leading expert on the famous Enigma cipher machine used by German forces during World War two. What is more, he owns one of these extraordinary machines and brought it along to his talk to members of Wells U3A on Wednesday 4th April.

With great clarity Mark explained how Enigma was developed by Germans just after WW1. It was designed to scramble messages sent by means of the relatively new system of wireless communication and was first patented by them in 1918.

The so-called Caesar cipher ( used by the Roman general and referred to by this name, even though he probably didn’t invent it) used a code where each alphabetical letter was transposed by, say, one letter. Thus, HELLO YOU could become IFMMP ZPV. The simple minded amongst us, seeing this on the screen, were better able to understand the principle behind Enigma’s system! The Enigma cipher machine transposed letters at apparent random, changing one letter for another by means of a complex system of three or more revolving rotors. Mark explained how these whirled around each time a letter was pressed on what looks very like an old-fashioned typewriter keyboard.

When words are divided up into clumps of four rather than their actual length (IFMM PZPV) the code becomes even more difficult to translate. In fact, we were told that by WW2 various versions of the ‘dazzling’ Enigma machine made possible 3 x 10 to the 114th variations of transposition. Or, again for us simple minded: more than there are atoms in the known universe. An identically set up machine and paper ‘code book’ with instructions for de-coding were of course necessary for the receiving end to make sense of the message.

The significance of Enigma in warfare was understood very early. Poland felt threatened by the German build-up of armaments in the late twenties and three mathematicians were set to working out the mechanism of Enigma; how to break its complicated codes. By 1932 these brilliant mathematicians had learned how the system operated and had built a replica. Aware of the significance of their discoveries, they escaped from Poland in 1939 when their country was about to be invaded and freely gave all this information to both Britain and France. It was on this basis that the men and women at Bletchley Park were able to set to unlocking the apparently un-lockable coding system.

Most of us were surprised to learn that the buildings and land at Bletchley Park were acquired as a centre for code breaking in 1938. This was seen as necessary as war loomed and being buried in the country, well away from London, Bletchley Park was in an ideal situation. Beginning with only 130 staff and a modest collection of huts around the original country house, the site developed rapidly. By the end of the war nearly 10,000 people were working there. An aerial photo shows the eventual extent of the campus - covering a huge area with row after row of huts surrounding the old house. Logistically it was a big operation: no one slept on the campus and staff, working in a series of constant eight-hour shifts were bussed in every day from billets scattered around the area.

We now know that it was at Bletchley Park that the working of the Enigma machine was eventually understood and - unbeknown to the Germans – what were thought to be its unbreakable codes were finally broken. Alan Turing’s ‘Bombe’ (measuring 6’ x 9’ x 3’) played a significant part in this. Breaking the codes led to their deciphering, and this in turn led to the distillation of the massively useful knowledge known as ULTRA. Passed onto the Army, Navy and Air force, it is considered that this knowledge significantly shortened the length of the war.

Throughout the war the islands of Britain relied on convoys arriving from the far side of the Atlantic to supply essential food and armaments. Controlled from a secret base in Liverpool, the ships, up to 150 at a time and travelling in great flotillas up to five miles square, were constantly threatened by attack by German U-boats. By late 1941 we were losing horrific numbers of ships, men and supplies to these lethal floating submersibles. After the war. Churchill admitted that the thing that frightened him most in those early years of the war was the U-boat peril.

In 1942 a U-boat was sunk in the Mediterranean, the paper work retrieved by British forces before it sank and Bletchley Park was now provided with these instructions for de-coding. The enemy was unaware that Enigma had been cracked, but it had been and our forces were at last able to work out where U-boats were lying in wait for the convoys. Apart from a disastrous period when the Germans further complicated the codes by expanding the number of rotors in their U-boat machines, numbers of ships lost fell dramatically. The involvement of America after Pearl Harbour affected the whole pattern of the war, but it was not until the more sophisticated U-Boat Enigma ciphers had been cracked, that Britain’s supplies by sea were relatively safe for the rest of the war.

After the lecture members were encouraged to have a go with the Enigma machine. Mark had managed to pack a mass of facts and figures into the talk and the audience thanked him enthusiastically for what had been a fascinating hour.