Artificial intelligence has successfully decoded a 217-year-old encrypted letter from Napoleon's era, revealing critical troop positions during a tense period in European history. The AI model, OpenAI's GPT-6 Astra, managed to transcribe and decipher the document in approximately six hours, a feat that had eluded researchers for decades. The findings highlight the strategic military movements of French forces in 1809, just before Austria's impending attack.