AI Helps Decipher Napoleon's Secret Coded Letter (3 Photos)

The GPT-6 Astra artificial intelligence system has successfully reconstructed the contents of a coded letter sent by Napoleon Bonaparte to one of his generals. The text had baffled researchers for 217 years.





According to reports, the breakthrough was revealed by Carter Church, an AI engineer at the American cybersecurity firm SentinelOne, who led the decryption effort.

Church leveraged the GPT-6 Astra model, which took roughly six hours to transcribe the symbols and reconstruct the message's original text.

Dispatched in 1809 on Napoleon's orders by his stepson, Eugène de Beauharnais, the letter was addressed to General Marmont, who was commanding French forces in Dalmatia at the time. Acting on the intelligence, Marmont was able to link up with Napoleon's main army, distinguish himself at the Battle of Wagram, and earn promotion to Marshal of France. The key to the document's cipher had long been lost.



The dispatch contained roughly 1,300 encrypted elements and 155 distinct symbols, including numbers, letters, and special characters. With no surviving cipher key, the AI relied on 33 previously cracked characters as a baseline and cracked the rest using simulated annealing.

The generated possibilities were cross-referenced against historical French texts and Marmont's surviving correspondence. In the letter, Napoleon briefed Marmont on the dispositions of French and allied forces on the eve of the campaign against Austria. Notably, the Emperor warned that Austria would be struck from multiple directions at once and was hurtling toward defeat.

"Austria is being attacked on all fronts simultaneously. Consequently, she is racing toward her own doom," he wrote.