The second world broke in 1939 and lasted till 1945. This span of 6 years is filled with intriguing stories of innovation, courage, valour and deception. Enigma is one such story.
Enigma, the backbone of Germany’s military communications, helped them orchestrate attacks without fear of interception. A device so sophisticated that it seemed unbreakable. Until a team of spirited individuals thought otherwise.
The Enigma code breakers’ mission was invisible and their victories unsung, until long after the war had ended. The minds who cracked the uncrackable, whose quiet triumph tipped the balance of World War II in the favour of the Allied Forces.
Let us unfold the story of the brilliant minds that made it possible with their perseverance, innovation, and sheer intellect.
The World War II
Under the leadership of Adolf Hitler, Germany invaded Poland on 1st September 1939. Britain and France had pledged to protect the sovereignty of Poland hence they declared war on Germany on 3rd September 1939. In a spectacular fall of dominos, more countries got sucked into the melee and thus the world got its second war!
Soon the world was divided into three groups:
- The Allied Powers: The United States, Britain, France, the Soviet Union, and China
- The Axis Powers: Germany, Japan, and Italy
- The Neutrals: Spain, Sweden, Switzerland, Portugal etc.
But beyond the roar of tanks and fighter planes, another war was being waged in the communications domain. As the war spread, intelligence became one of the most valuable weapons. Nations needed secure ways to communicate military orders, coordinate attacks, and deceive their enemies.
The Communications War
Communication plays an important role in any large-scale deployment. World War II was no different. The armies needed to communicate to convey orders, carry troop movements and coordinate attacks. Key modes of communication available at that time were:
- Radio transmissions: Used by armies, navies, and air forces to relay strategic orders across continents.
- Telegrams: Delivered critical intelligence between commanders.
- Courier services: Secret agents carried classified documents across dangerous territory.
But where there is communication, there is also eavesdropping. Most of the above messages had simple or no encryption thus they were susceptible to interception. Both Allied and Axis forces intercepted messages daily, hoping to figure out enemy plans.
The Game of Eavesdropping
The British, through their Government Code and Cypher School (GC&CS), stationed at Bletchley Park, became masters of listening in on German communications. Meanwhile, the Germans intercepted Allied convoys in the Atlantic, to orchestrate U-boat attacks.
A pivotal moment in intercepted messages occurred in 1941, when British intelligence deciphered German naval communications, leading to the sinking of the powerful battleship Bismarck.
In another incident, German codebreakers had intercepted messages about the Convoy PQ 17 route in 1942. This led to the destruction of 24 out of 35 ships by the German U-boats.
Birth of Encryption
Military encryption dates back centuries and it had existed in primitive forms for centuries. However, it was the First World War that saw the rise of its use and importance in military strategy.
With the advent of radio communications, armies required more secure methods to protect their strategies. Encryption became essential to ensure messages remained private even if intercepted.
This led to the development of various communication encryption devices. The Enigma was one such device. A device well ahead of the others.
The Enigma
The Enigma was originally a commercial device invented in the 1920s. It used rotating mechanical rotors to scramble letters in complex ways, making it nearly impossible to decode without knowing the exact settings. It was further upgraded by the German military.
The machine was deployed across German forces, the Wehrmacht, Luftwaffe, Kriegsmarine, and SS. Each branch used slightly different settings. With over 150 quintillion possible settings no one could ever decode its messages.
The machine transformed ordinary messages into unreadable gibberish and soon became the lifeline of the German army. The settings were updated daily, and messages remained hidden even when transmitted openly over the airwaves.
The Code Had to Be Cracked
Naval Enigma proved the deadliest for the Allies. German U-boats stalked Allied shipping routes, aided by intelligence delivered via Enigma-encrypted messages.
By the early 1940s, the Allies recognised that breaking Enigma was not just useful, it was necessary. If they failed, Germany would continue to operate in secrecy, gaining an advantage in every battle. The only way to dismantle Hitler’s war machine was to read its plans before they were executed.
The Allies knew that if they cracked Enigma, they could win the war. The mission to break Enigma became one of the top priorities for Allied intelligence.
And at the heart of this mission was a quiet estate in Buckinghamshire, England. The Bletchley Park.
The Crack Team
Bletchley Park became the epicentre of the greatest codebreaking effort in history. An eclectic mix of mathematicians, linguists, chess champions, engineers, and crossword enthusiasts was assembled.
At the core of this team were several brilliant minds:
- Alan Turing: A mathematical genius from Cambridge, Turing’s groundbreaking work on algorithms and theoretical computing laid the foundation for modern computer science.
- Dilly Knox: A seasoned cryptanalyst, Knox had worked on enemy codes during World War I. His deep understanding of classical cyphers was invaluable in the early stages.
- Gordon Welchman: Another Cambridge mathematician, Welchman contributed to designing the operational systems that enabled rapid decryption.
- Joan Clarke: A gifted mathematician, Clarke worked closely with Turing and was a key member of the team deciphering daily Enigma settings.
- Marian Rejewski: A Polish cryptanalyst who, along with his colleagues Jerzy Różycki and Henryk Zygalski, made the first breakthroughs in understanding Enigma’s structure.
“Sometimes it is the people who no one imagines anything of who do the things that no one can imagine.”
Alan Turing
The Bombe
This team knew that human calculations alone wouldn’t crack Enigma. They needed machines to do what human brains couldn’t. Test thousands of combinations within minutes.
Alan Turing spearheaded the development of the Bombe. An electro-mechanical device that could simulate Enigma’s settings and identify potential key matches.
Each Bombe machine could analyse thousands of possible combinations per minute. Dozens of Bombes ran day and night at Bletchley Park, narrowing down the possible settings until a match was found.
Once a day’s settings were cracked, that day’s messages could be read for a limited window before the settings changed again.
Challenges and Breakthroughs
Breaking Enigma was a race against time. Each day the codebreakers had to start afresh, as the Enigma settings reset every 24 hours. A single error could lead to days of missed intelligence.
Furthermore, the Germans continued to improve their encryption. The Kriegsmarine added more rotors and created a more complex version of Enigma. At times, breakthroughs came from unexpected sources, such as capturing German codebooks. Or finding predictable phrases in messages (like weather reports or the phrase “Heil Hitler”).
One such victory came when the British captured U-559, a German U-boat, and retrieved key Enigma documents. These helped the codebreakers decipher the previously unbreakable Naval Enigma.
The Triumph
By 1941, Bletchley Park was reading thousands of German messages a day. The success was codenamed Ultra, a secret so valuable, Churchill declared it must remain hidden at all costs.
With Enigma broken, the Allies gained, unparalleled access to German military plans. They could counter strategies before they happened, sabotage attacks and intercept supplies. This intelligence is estimated to have shortened the war by several years, saving millions of lives.
Convoys were rerouted to avoid U-boat traps. The British gained prior warnings of German operations. In 1943, Ultra helped Allied forces win the Battle of the Atlantic, ensuring a steady flow of troops and supplies from America to Europe.
The most famous use of Ultra was in the run-up to D-Day. Allied leaders fed false information to the Germans, tricking them into believing the invasion would happen at Pas de Calais instead of Normandy. Meanwhile, decrypted Enigma messages confirmed that the deception was working.
Afterlife of the Code Breakers
Despite their immense contributions, many members of the Enigma-breaking team remained unrecognised for decades. Alan Turing, one of the greatest minds in computing history, faced tragic persecution after the war.
In 1952, Turing was prosecuted for homosexuality, a criminal offence in Britain at the time. He had been in a consensual relationship with a man named Arnold Murray, and when Turing reported a burglary at his home, the police uncovered his sexuality during the investigation.
He was given a cruel choice between imprisonment, or chemical castration. Turing chose the latter, which led to devastating side effects, including depression, impotence, and physical changes like breast development. On June 7, 1954, Alan Turing was found dead in his home in Wilmslow, England due to cyanide poisoning.
In later years, the world came to understand the true depth of their achievements, honouring them with awards, films, and memorials.
Conclusion
The story of the Enigma Code Breakers is one of brilliance, perseverance, and triumph. It reminds us that wars aren’t won only with weapons they are won with knowledge, strategy, and determination.
These heroes didn’t fight with guns or tanks, but their genius and technological innovation became some of the most powerful weapons in history. Their legacy lives on in modern cryptography, artificial intelligence, and cybersecurity.
They didn’t seek glory. But history remembers them as heroes, unsung, unseen, and utterly unforgettable.
The movie ‘The Imitation Game’ is based on this story.
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