An AI engineer used OpenAI's GPT-6 Astra to decrypt a coded letter from Napoleon to General Auguste de Marmont sent in 1809, revealing French and Austrian troop movements on the eve of war.
A coded letter carrying a message from Napoleon Bonaparte to one of his senior generals has been cracked by AI after 217 years. The contents of the letter, sent by Eugène, Napoleon's stepson, on the emperor's instructions, had remained a mystery since it was sent to Auguste de Marmont in 1809.
Carter Church, an AI engineer at cybersecurity company SentinelOne, said this week he had used OpenAI's GPT-6 Astra system to decrypt and transcribe the message for the first time. The letter contained details of French and Austrian troop movements on the eve of war between France and the Habsburg Empire. The note contained 1300 characters, some of which represented letters and other old words.

AI System Decodes Lost Cipher
The cipher to decrypt the message has been lost, meaning the letter's contents have been unknown for more than two centuries. GPT-6 Astra, an advanced version of the AI system that powers ChatGPT, spent six hours transcribing the characters and mapping them against work from cryptographers that had solved 33 of the characters. It then decoded the message using a technique known as simulated annealing.
Simulated annealing is a process of trial and error in which multiple candidate words are tried to see whether they fit, and compared them to Marmont's existing writing. While the process could have been done by hand, it would have been a laborious process that no cryptographer to date has accomplished. Church said he had never attempted to decode a cipher before but had been inspired to after seeing an AI model decode a 1941 German army message.
In that case, Carter Leffen, another tech developer, simply told the GPT-6 Astra AI tool to find and decrypt an unsolved Enigma message, which it managed in around 10 hours. Recently released AI models have been found to be highly capable of solving mathematical problems as well as deciphering code. Decrypting ciphers often involves painstaking work of patching together multiple possible combinations of words, something that AI systems can do much more quickly than humans.
Troop Details in Napoleonic Letter
Researchers have raised concerns that the same capabilities will be used to unmask anonymous online profiles, by matching their writing patterns and other identifiers with real people. The letter to General Marmont, who was stationed in modern-day Croatia and separated from Napoleon's main armies, came as the Habsburgs prepared for war with France to regain lost territory.
It contains details of the locations and strength of the French and Austrian forces and instructs him to prepare to march and not be intimidated by a few troops or a gathering of rabble. The letter adds that Austria will be attacked at once on every side and is consequently hastening towards her ruin. Marmont's army was ultimately able to break out of Croatia and help Napoleon defeat Austria at the Battle of Wagram.
Marmont was made a Marshal, a rank awarded to his senior generals.
This story was compiled and edited by the HeadTopics newsroom and HT AI from the reports above.
Artificial Intelligence Cryptography Napoleon Bonaparte Historical Documents Military History GPT-6 Astra Coded Letter Decryption Auguste De Marmont Battle Of Wagram AI Decryption General Marmont
Australia Latest News, Australia Headlines
Similar News: You can also read news stories similar to this one that we have collected from other news sources.
MI5 warns UK universities over alleged Chinese espionage front companyMI5 has issued a public warning to UK universities that the China General Technology Research Institute, also known as the China Academy of General Technology, is a front organisation linked to China's Ministry of State Security. The group is alleged to have funded academic research in areas including artificial intelligence, cybersecurity, covert communications and steganography, with sensitive information reportedly passed to Chinese intelligence. MI5 says collaborations could face prosecution under the National Security Act 2023.
Read more »
Catholic clergy sexually abused nearly 1,000 Massachusetts children over decades, report findsNo new indictments from eight-year investigation as state attorney general says church knew about abuse
Read more »
South Africa omit Johannesburg for Australia Test tour in bid to negate paceCricket South Africa has scheduled Tests in Durban, Gqeberha and Cape Town, leaving out Johannesburg where Australia have won all three of their visits since 2002. The move is designed to favour South Africa's seam bowlers and neutralise Australia's fast-bowling attack.
Read more »
