AI-rewritten: This is a summary of an article from Tom’s Hardware, rewritten by AI (Qwen, running locally) to make it easier to read. The facts come from the original article – read it for the full story.

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Carter Church, an AI engineer at SentinelOne, used OpenAI’s GPT-6 Astra to decipher a 217-year-old military code that had remained unsolved since the Napoleonic Wars. The cipher was part of Cryptiana’s Unsolved Historical Ciphers list and contained a troop briefing sent to French General Auguste de Marmont. Although the message originated from Eugène de Beauharnais, Viceroy of Italy, it is not signed by any specific individual. Church states that Astra solved the puzzle in approximately six hours after receiving only a single image and prompt.

The deciphered text completes a missing sentence from Napoleon’s 1865 memoir regarding preparations for an Austrian invasion. The original memoir breaks off mid-sentence with the phrase "a handful of …" while the newly revealed page adds the words "a gathering of rabble." Church notes that Astra utilized a partial key previously unconnected to this letter and employed its multi-modal processing capabilities, including a simulated-annealing solver, to crack the remaining symbols.

To verify the accuracy of the work, Cryptiana has marked the cipher as solved by Satoshi Tomokiyo, who maintains the online database. Church explains that the solution is mechanically testable against the ciphertext using the published script available on his blog. The breakthrough demonstrates how modern artificial intelligence can process historical military secrets using simulated-annealing techniques to solve complex ciphers without needing extensive prior training data.