ðŸ‡ðŸ‡· Croatian, 4 October 2026, historical-cryptography
AI Cracks 217-Year-Old Cipher of Napoleon's Army
A model of artificial intelligence deciphered a 1809 letter encrypted by Napoleon's forces, revealing troop positions and a warning to General Marmont.
The model, GPT-6 Astra from OpenAI, worked for approximately six hours to crack the code, which had resisted attempts by researchers for decades. The letter was written in 1809 and contained a coded report on the deployment of military forces. The AI model first transcribed the image of the document, then analyzed the handwritten symbols and identified 175 duplicate characters.
The Astra model performed a series of tasks, including image transcription, homophonic substitution cipher analysis, and code writing, before comparing the results with historical records. The deciphered text revealed the positions of Bavarian, Polish, and French forces.
The letter was written during a time of preparation for war in Europe, with Austria preparing to fight against France, and a significant portion of French forces tied up in Spain. The deciphered text also included a direct warning to General Marmont to avoid alarming the enemy with troop numbers or assembled forces.