An encrypted letter to French general Auguste de Marmont was decoded 217 years after it was written using artificial intelligence. The document was written in March 1809 on the orders of Napoleon Bonaparte, who instructed his stepson Eugene de Beauharnais to convey information to Marmont about the location of the French and allied armies.
The GPT-6 Astra model was used for decoding. According to Carter Church, an artificial intelligence engineer at the American company “SentinelOne“, the system processed the document for about six hours. She started with an image of the original cipher, not a ready-made transcription.
“The letter contained 1,300 cipher units and 155 different characters“, Church wrote in the description of her work. Among the characters are numbers, letters and special handwritten characters. The key to the cipher has not been preserved.
How the lost key was recovered
The analysis used 33 predetermined character values, which explain about a third of the text. The remaining matches were searched for using an algorithm based on the simulated annealing method - a technique for finding the most likely solution for a large number of possible combinations.
The suggestions were checked against all occurrences of the corresponding character in the document. The resulting text was also compared with French language models, as well as with preserved texts of Marmont. According to Church, a re-analysis that excluded the general's memoirs and other Napoleonic texts gave the same result.
The military information in the letter
The deciphered document was sent from the headquarters of Eugene de Beauharnais, Viceroy of Italy, to Marmont, who at the time commanded French forces in Dalmatia. It describes the positions of the army of the Duke of Danzig near Munich and Passau, the Polish troops of Prince Józef Poniatowski near the Vistula, the Saxon units near Dresden and other French formations.
The numbers of individual armies are also indicated - 40,000 Bavarians, 30,000 Poles, 80,000 French near Bayreuth, 60,000 people near Ulm and Denauwert and 40,000 soldiers near Augsburg and the Lech River.
„Austria will be attacked simultaneously from all sides and is therefore rapidly moving towards its doom“, reads the read text.In the letter, Marmont is urged not to be afraid of small enemy units when he receives an order to begin moving. The content coincides with Napoleon's instruction of March 16, 1809, to Eugene to send the general encrypted information about the disposition of the troops.
The estimate places the document in the last days of March 1809, immediately before the Austrian offensive. On April 10, Austria crossed the Inn River and the war, known as the War of the Fifth Coalition, began.
Sources: RBC