AI Deciphered Napoleon's Secret Order
- 3.10.2026, 10:56
A complex cipher that people had been unable to crack for 200 years was successfully cracked in just six hours.
Artificial intelligence helped decipher a secret military letter from the Napoleonic Wars that had remained a mystery to historians and cryptographers for more than two centuries. The complex cipher was cracked in just six hours, according to RMF24.
In 1809, France, under Napoleon’s leadership, was preparing for a conflict with Austria. To protect military communications, the French military used complex ciphers.
One such document remained undeciphered for over 200 years. The letter came from the headquarters of Eugène de Beauharnais, Viceroy of Italy. It contained encrypted military instructions for General Auguste de Marmont.
The document was not written directly by Napoleon. The message was of great strategic importance, so orders were given to deliver it only to a trusted officer.
Six Hours Against Two Centuries
For decades, researchers have tried to decipher the document, but a complete decryption has never been published.
The breakthrough came when Carter Church, an engineer at SentinelOne, used OpenAI’s advanced GPT-6 Astra artificial intelligence model.
According to Church, the AI automatically transcribed the image of the document, analyzed the complex homophonic substitution cipher, wrote the necessary code, and compared the results with historical data.
“Astra split the array—which was 1,202 by 1,836 rows—into individual lines, counted the characters, determined which of the 175 hand-drawn characters were duplicates, and only then began the decryption process,” Church explained.
The entire decryption process took about six hours.
What Was in the Encrypted Letter
The decrypted document turned out to be part of the French military strategy in the spring of 1809.
The letter contained information on the positions of Bavarian, Polish, and French troops, as well as numerous instructions for General Marmont, who commanded the French forces in Dalmatia.
At that time, the French command was preparing for an impending Austrian offensive. Marmont risked being cut off from the rest of his forces, so receiving the appropriate orders and information was of critical importance.
An analysis of data on troop strength, unit deployments, and officers’ ranks also allowed Carter Church to date the document to late March 1809—approximately two weeks before the start of the Austrian offensive.
New Opportunities for Deciphering Old Documents
Deciphering the letter using artificial intelligence opens up new opportunities for researching historical documents and ancient ciphers.
AI’s ability to quickly analyze large amounts of information, recognize symbols, write code, and compare results with historical data can be applied in fields such as history, cryptography, and other auxiliary historical sciences.