Enigma Machine

Movies frequently misrepresent history, and The Imitation Game made some awful errors in the name of making an exciting movie. However the real story of the years of hard work, genius and secret machinations should be told as well.

At the end of the First World War, Arthur Scherbius a German electrical engineer applied for a patent on his cipher machine, which came to be known as ENIGMA. Little did he know that his invention was going to shorten the next war by being both too good and not quite good enough. After many knock backs, Arthur finally came up with a machine that convinced the German High Command that it was, like they thought themselves were, invincible. It had a complicated series of rotors, gears, cables and keys, but with a little training most soldiers could be taught how to operate it. The machine arrived on the German military horizon at the perfect time, although Arthur was to die in 1929, it became the principal coding method for the Nazi army, air force and navy – it became indispensable.

The British set to work on cracking the code as soon as German radio traffic was received, but they had a couple of serious disadvantages: Firstly, they had little idea of the nature of the machine but more importantly, they were attacking it linguistically – it took the Poles to show the key to the puzzle wasn’t with words, it was with numbers.

A few months before hostilities broke out two British cryptanalysts and their French counterparts visited Poland and were taken to a secret location in the Pryski Forest. In an amazing spirit of generosity, the Poles not only showed their Allies how to break the code using one of the first real computers (called a bombe for its ticking sound!), they had made a copy of the Enigma machine almost entirely by deduction alone!

From this start, the British were able to build bombes at their secret base in Bletchley Park and eventually crack the codes the Germans were using. Aside from the brute force method of trying every single combination, one by one – the British discovered ways to cheat the system. The German military made stereotypical errors which the Brits could exploit. For example, German submarines would invariably begin their day by transmitting a weather report – weather in Europe typically moves East to West so that a submarine in the Atlantic can help predict the weather in Europe. Also, just like in the movies, Germans finished each transmission with “Heil Hitler!”. The codebreakers called these cheats ‘cribs’. The movie ‘The Imitation Game’ gives a broadly correct description of the codebreaking process but with two serious errors.

Firstly it totally ignores the invaluable assistance of the Polish cryptanalysts, without which, years could have been spent fruitlessly following a linguistic approach – looking for patterns in words. Some of the original codebreakers were chosen for their ability to do crossword puzzles!
Secondly the movie makes a common mistake of being afraid to use the information gained from cracking the code in an operational environment. Turing is shown not reporting a Nazi submarine ‘wolf pack’ in the path of a British convoy.

Sinking of the Linda Blanche out of Liverpool

If the information gained from cracking the code could not be used, then what was the point of the crack? It was often used to detour convoys, many lives were saved as a result. Churchill designated the source of the intelligence to be ‘Most Secret’ and it was given the code name ULTRA. All ULTRA information was disguised and jumbled with other data so that if the decode got into enemy hands, they could not infer that their code had been cracked. Only a very few generals and similar ranks knew of the breakthrough, they were briefed by special liaison officers. The material was read in their presence and immediately destroyed. No secret was more closely guarded than the fact the allies could read every message the Nazis sent. Every single spy the Germans sent into Britain was compromised as a result of cracking this code. On one occasion a spy was identified because Bletchley had discovered the details of some dental work he needed when a parachute training exercise in occupied France had gone wrong! There were occasions when coded messages were sent to Hitler and his High Command that the codebreakers of Bletchley Park had received the message, decoded it, translated it into English and placed before Churchill, before Hitler himself had seen it. With this sort of intelligence, the Nazis were almost unable to spring any tactical surprises on the Allies. With the exception of Operation WATCH ON THE RHINE – the counter attack that led to the Battle of the Bulge, every major Nazi move and multitudes of minor ones was predicted, planned for and countered, to the total consternation of the German High Command. So many submarines were sunk before they could do any damage that the German Navy was convinced that the Allies had some sort of underwater radar. At the end of the war, some 28,000 – 75% of German submariners – did not go home. In 1939 and 1940 of the war, before ENIGMA was cracked only 33 German submarines were sunk. In 1943 and 1944 nearly 500 U Boats went to the bottom of the sea. Sinkings slowed down to only 120 in 1945 only because the Nazis were running out of submarines and men able to sail in them.

Given these extraordinary and very necessary security measures, it is hard to fathom the actions of the American General Eisenhower prior to Operation Torch. Torch was the invasion of North West Africa, where the Americans were to push from the west and with the British attacking from the east, leaving Rommel no choice but to face every General’s nightmare – to fight on two fronts. Much of north-west Africa was controlled by the French and to their shame and the disgust of many of their fellow countrymen, these French were fully prepared to oppose the landing. Eisenhower sent General Mark Clark to smooth the way with the French leaders on a British submarine with a few British commandos to guard him. He was lucky not to be captured by German soldiers or even betrayed by the treacherous French. If he had been handed over to the Gestapo, the consequences would have been disastrous for the entire allied cause. He could have told the Germans under torture that Enigma was cracked!

Estimates vary as to the impact of cracking the code, whether it shortened the war by two years or four, we will never know – Churchill said at least once that it made victory certain and without it, winning the war would have been a doubtful gamble. The ENIGMA machine was so good, Nazi generals were genuinely shocked when told it was broken, so good that they thought it was impregnable. But fortunately for western civilization, the men and women of Bletchley Park and their Polish forbears were just a little bit better.

I am indebted to my friend Paweł Żuk who researched the Polish contribution for me – I knew it was significant, but I didn’t know it was the single biggest factor in Allied success.
(c) Paul Hannah 2019


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