A military secret from 1809 broken by artificial intelligence

In 1809, Europe was on the brink of war. France, under Napoleon, was preparing for conflict with Austria. In these turbulent times, military communications played a key role, and their security was ensured by complex ciphers. One such document, written on Napoleon's orders, remained undeciphered for over 200 years, posing a challenge to historians and cryptologists.

The letter, which was not directly authored by Napoleon, came from the headquarters of Eugène de Beauharnais, Viceroy of Italy, and contained coded military instructions to General Auguste de Marmont. The message was of key strategic importance and was sent with the highest precautions - it was to be "written in code" and transmitted only by a trusted officer.

Over the decades, numerous researchers have attempted to decipher the document, but none have managed to publish a complete decipherment. The breakthrough came only now when Carter Church, an engineer from the cybersecurity company SentinelOne, used the advanced OpenAI GPT-6 Astra artificial intelligence model.

According to Church's account, the AI ​​model not only automatically transcribed the document image, but also analyzed a complex homophone substitution cipher, wrote the required code, and verified the results with historical data. The entire decryption process took just six hours.

Church described how the AI works in detail:

"Astra split the 1,202 by 1,836 table into lines, read the characters, identified which of the 175 hand-drawn characters were the same symbol written twice, and only then began breaking the cipher."

The decrypted document turned out to be a key element of French war strategy in the spring of 1809. The letter contained detailed information about the positions of Bavarian, Polish and French troops, as well as numerous instructions to General Marmont, who commanded the French troops in Dalmatia. Due to the impending Austrian offensive, Marmont could be cut off from the rest of the forces if he did not receive appropriate orders and information.

By analyzing detailed data on troop numbers, unit positions, and officer titles, Carter Church was able to precisely date the document to late March 1809, approximately two weeks before the start of the Austrian offensive.

The decipherment of Napoleon's letter by artificial intelligence is a breakthrough not only for historians, but also for everyone who studies ancient documents and ciphers. The speed and efficiency of AI open up new possibilities in the fields of history, cryptography and auxiliary sciences.