5 Famous Code Breakers Who Changed the Course of History

computer code breaker

Governments have risen and fallen due to the work of the world’s most notorious code breakers. They have taken impossible-looking cyphers and unlocked their secrets. From cracking the Nazi’s enigma code to intervening in colossal global events such as the Falklands War and the Cuba crisis, the world would look very different today without these incredible minds.   

While the ‘father of computer science’ Allan Turing is perhaps the most well-known cryptographer to some out of Bletchley Park, there are other star players in the hidden world of cryptanalysis. 

Here we take a look at 5 famous code breakers who changed the course of history: 

Pryor’s WWII wartime secrets

World War II was an intensely scary and horrific time for all those that served in the armed forces. As well as those waiting for peace to finally reach their homes. 

While Turing and his team were working to create the revolutionary computer “the bombe” that British Intelligence used to unravel Hitler’s infamous WWII military code, sub-lieutenant John Pryor was working behind enemy lines. 

Captured at Dunkirk, Pryor was imprisoned in a German POW camp. Unknown to his captors, Pryor hid a secret code within the letters that he was permitted to send to his parents in Cornwall. As he hoped, these letters were intercepted by British Intelligence and used to gain wartime information that would turn the tide. 

Famously, one of Pryor’s letters contained vital details about HMS Undine. A British submarine sunk in 1940 within a detailed description of the POW camp’s vegetable patch!

“Gentleman Jack”

Anne Lister is a celebrated 19th century Yorkshire landowner, mountaineer and traveller. She earned the name “Gentleman Jack” due to her open lesbianism, which was a punishable offence that could have earned you a death sentence back then. 

But it is her remarkable tale, journaled in her personal diaries, that have made her the icon we love today. Within their pages, Lister wrote over 4 million words within their pages, including intimate details of her sex life. However, she wrote everything in a code she derived from a mixture of algebra and Greek. 

In the 1930s, Lister’s diary fell into the hands of John Lister, the final resident of her estate in Shibden Hall, Halifax. Due to the revealing nature of the diaries, he was advised to burn them. However, he could see their future importance, and to honour his former landlady, he hid them behind a wall panel to preserve them. 

Room 40

Before Bletchley Park rose to fame, a generation before, there was Britain’s little-known WWI cryptoanalysis section, Room 40. 

Created in October 1914. In response to a series of documents and a codebook recovered from a German warship. The largely amateur outfit was formed in London’s Whitehall. The team was made up of volunteer linguists, engineers and cryptography enthusiasts that worked alongside top MI1 intelligence officers. 

Together they pored over intercepted signals from Germany and eventually worked up a basic understanding of the enemy’s rudimentary cyphers. 

Fast forward to 1917, and the team cracked a German diplomatic transmission to Mexico, which was instrumental in changing the course of the war. This document was the Zimmerman Telegram, pledging military support from Berlin to the Mexican government in an attempt to regain lost territory from the southwestern USA. 

Once Room 40 had sufficient evidence of the coo, they eagerly forwarded their findings to Washington. Combined with Germany’s unrestricted submarine warfare plaguing the Atlantic, this moment is seen as one of the significant factors that made the US join the war. 


Back in the 1920s, US military cryptographers were working behind the scenes to intercept and decode Japanese naval and diplomatic cables. The joint army and navy taskforce’s operation was known as Magic. 

Magic was in motion for decades. Throughout the 1930s, the team became so good at decoding that it was believed that Magic could decipher the intercepted Japanese codes quicker than the intended recipients. 

After Berlin and Tokyo became firm allies in the 1940s, the Nazi’s shared their Enigma tech to help their newest allies scramble communications. Nicknamed ‘purple’ by the Magic team, even this more complicated series of cables was broken by the group. 

From learning the Japanese ambassador’s instructions to formally sever ties with the U.S. ahead of the then-unknown plans to attack Pearl Harbour, to intercepting an advanced warning for a planned strike on the U.S. base at Midway in 1942 – Magic was a lifesaving operation that undeniably turned the tide. 

Linear B

Linear B is an ancient Bronze Age script that was discovered on a handful of clay tablets and sealings in the second palace at Knossos, Crete. While the palace was famously burned down to its foundations by the fire that baked these clay tablets, they have survived in good condition for millennia. 

No one really knows when the script first came into use, but it is generally thought that they originated from around the fifteenth or sixteenth BCE, as that fits with the idea that they belonged to Minoan culture. The other school of thought believes that the invading Myceneans brought the script with them from the mainland and then introduced it to the surviving Minoans. 

While the tablets origin story is rooted in part history, part speculation, the code was finally cracked in the 20th century by English linguist Michael Ventris. However, there is more to that story. 

American classicist Alice Kober began studying the elusive script way back in the 1930s. Kober’s recently catalogued archive at the University of Texas shows that decoding Linear B became her life’s work, up until her death in 1950. Now it is thought that Ventris would never have mastered the code without Kober’s instrumental work. 

Codebreakers are the movers and shakers. They are the ones who work diligently behind the scenes to unearth secrets and prevent global disasters, namely war. But more than that, they are artists, scientists, linguists and have a thirst for figuring out the complexities of human nature. Do you want to put your codebreaking skills to the test?

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