By GB News (World News) | Created at 2026-10-02 11:16:04 | Updated at 2026-10-02 14:27:03
3 hours ago
A Napoleonic letter that had baffled cryptographers for more than two centuries has finally been deciphered with the help of AI.
An AI engineer at cybersecurity firm SentinelOne has successfully deciphered the coded message.
Carter Church announced this week that he employed OpenAI's GPT-6 Astra system to unlock and transcribe a letter dispatched to General Auguste de Marmont in 1809, revealing previously unknown intelligence about French and Austrian military deployments.
The encrypted correspondence was sent on the eve of conflict between France and the Habsburg Empire, as Austria sought to reclaim territory it had lost.
No one has managed to decode the letter's contents in the 217 years since it was written and the original cypher has been lost to history.
The letter was written by Napoleon's stepson Eugène, who wrote it under the emperor's direct orders.
The 1,300-character coded note used symbols that stood for both individual letters and archaic words, making manual decryption extraordinarily difficult.
GPT-6 Astra, the enhanced iteration of the artificial intelligence underpinning ChatGPT, worked for six hours to crack the message.
A Napoleonic letter that had baffled cryptographers for more than two centuries has finally been deciphered with the help of AI
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It began by cross-referencing its analysis against prior efforts by cryptographers who had identified 33 of the characters.
The system then applied a method called "simulated annealing," systematically testing potential word candidates and checking them against Marmont's known writings.
Though theoretically achievable by human hand, no cryptographer had ever completed the task.
The decoded message disclosed the positions and strength of both French and Austrian forces, and ordered Marmont, based in what is now Croatia, to cut off Napoleon's principal armies and ready his troops for movement.
An AI engineer at cybersecurity firm SentinelOne has successfully deciphered the coded message
CARTER CHURCH
The general was told not to be "intimidated by a few troops or a gathering of rabble."
In a striking passage, the letter declared: "Austria will be attacked at once on every side. She is consequently hastening towards her ruin."
The intelligence proved vital.
Marmont's forces successfully fought their way out of Croatia and joined Napoleon in defeating Austria at the Battle of Wagram, after which Marmont received the prestigious rank of Marshal.
The encrypted correspondence was sent on the eve of the conflict between France and the Habsburg Empire
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Mr Church had no prior experience in deciphering codes but was motivated to try after witnessing another tech developer, Carter Leffen, use the same GPT-6 Astra tool to crack an unsolved Enigma message from 1941.
Mr Leffen had simply instructed the AI to locate and decrypt the German army communication, a task it completed in roughly 10 hours.
Recent AI models have shown remarkable proficiency in both mathematical problem-solving and code-breaking, performing the painstaking combinatorial work of decryption far faster than any human could.
However, researchers have warned that these same capabilities could be turned toward identifying anonymous internet users, with AI potentially matching writing styles and other distinguishing markers to real individuals.
