Enigma e`nig´ma noun A dark, obscure, or inexplicable saying; a riddle; a statement, the hidden meaning of which is to be discovered or guessed. A perplexing, baffling, or seemingly inexplicable puzzle.
The device you see in the photos altered the course of the Second World War. From its inception in 1918 to the end of 1943, when its encrypted messages were broken almost continuously, the Enigma machine had a significant impact on the Battle of the Atlantic.
With the help of these devices, German U-boats coordinated their ‘wolf pack’ tactics successfully against Allied shipping. But once British scientists managed to crack the German code, convoys could avoid the enemy and begin anti-submarine warfare in earnest.
Due to the code-breaking methods developed by Polish and British scientists, historians predict that the Second World War was shortened by no less than three years.
Origins and Development
In 1918, the first rotorized cipher machine was patented by Arthur Scherbius of Germany. This developed into the Enigma-A and B in the early 1920s but the size and weight of these machines (50 kg) restricted their military use until the advent of the Enigma D in 1927.
By using a reflector as the fourth rotor, which directed the current back through the first three rotors, the Enigma machine became significantly lighter and smaller.
However, the code of the Enigma D was broken by 1935, prompting the addition of a front plug-board that scrambled the message further. When an fourth rotor was added, this became the Wehrmacht Enigma, used by the German Army.
The German Kriegsmarine (Navy) adopted this model as well but increased the number of rotors to eight in 1942, which were used interchangeably.
This encryption device was used by many German military branches to encode and decode vital information but it was used to best effect by the Navy or Kriegsmarine to coordinate U-boat attacks.
Known as ‘rudeltaktik’ in German – literally ‘pack tactic,’ this approach mirrored the way a wolf pack operates. If a convoy was sighted by an individual U-boat, an encoded message would be radioed to other submarines, calling them in to attack.
The Enigma Machine at TMM
The Enigma Machine in the Naval Museum of Alberta at TMM is known as the Enigma-K, and was introduced in 1927. Because it was built by the Swiss, its box is slightly different from the German design and it lacks the ‘Enigma’ name plate of German machines.
Unlike the war-time Kriegsmarine Enigmas, this style only had three rotors and a reflector disk on the left and was comparatively easy to break. However, it was still used by the Swiss Army and the Italian Navy throughout the war.
So who knows? The example here could have rode under the waves in an Italian submarine or jostled around in the back of a Swiss communications truck!
Breaking the Code
Poland was the first nation to crack the codes of the 1930s machines. Marian Rejewski, Henryk Zygalski, and Jerzy Rozicki led these efforts, developing an electrical-mechanical device called the "Bomba".
This machine searched for daily rotor settings by running potential letter combinations through until it reached the correct order. But by 1939, the Enigma design had grown too complex and it fell to the British to break the wartime codes.
Bletchley Park and Alan Turing
At the Government Code and Cipher School at Bletchley Park in England, scientists created their own version of the Bomba. Alan Turing and Gordon Welchman pioneered this new design, which searched for ‘cribs’ or suspected plaintext words. ‘Cribs’ would be recurring and Turing discovered that ‘eins’ or ‘one’ appeared in 90% of messages. Using these words, it was possible to determine the rotor settings used to encrypt the entire message.
This code-breaking process was called ‘Ultra’ and had to be used carefully, lest the Germans found out their codes had been cracked. As commander of the U-boat arm, Grossadmiral Karl Dönitz monitored the effectiveness of his force closely.
When German codes were broken continuously by the end of 1941 and U-boat losses increased, the Kriegsmarine Enigma design was complicated further by adding a fourth rotor and supplying six others to use interchangeably. Ten nerve-wracking months went by before Bletchley Park could break these new codes.
The Tide of War Changes
Discovering that a fourth, interchangeable rotor had been introduced, Turing developed a newer version of the Bombe but the biggest breakthroughs were made after codebooks, which contained the daily rotor settings, were captured by the Royal Navy from German weatherboats.
By this time, Bletchley Park employed over seven thousand workers and nearly all German communications were collected by listening stations positioned throughout the United Kingdom. The tide of the U-boat war had turned.
Allied shipping could avoid enemy positions and destroyers could now actively hunt for U-boats. Over seven hundred submarines and thirty thousand German crewmen were lost during the Battle of the Atlantic – more than half of these after 1943.
Without the efforts of Alan Turing and the tireless workers at Bletchley, the Second World War may have lasted another three years. But these individuals were not recognized for their efforts until the 1970s when the information could be declassified.