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Napoleon's code is cracked after 217 years: Scientist uses AI to read a mysterious letter written by the Emperor in 1809

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Cite

Best, S. (2026, October 2). Napoleon's code is cracked after 217 years: Scientist uses AI to read a mysterious letter written by the Emperor in 1809. Daily Mail. https://www.dailymail.com/sciencetech/article-16177883/Napoleon-code-cracked-217-years-AI.html?ns_mchannel=rss&ns_campaign=1490&ito=1490

Dated when The Aporia collected the article, usually within hours of publication. Check the original for its exact date and byline.

Daily Mail · collected 2026-10-02 · by Shivali Best

Quick Summary

Carter Church used artificial intelligence to decode a mysterious letter written by Napoleon Bonaparte to his general Auguste de Marmont in 1809. The bulk of the letter was encoded with two-digit numbers and symbols, and AI model GPT-6 Astra successfully deciphered it within six hours. The decoded message reveals strategic details about French and allied army locations and advises Marmont not to be intimidated by his isolated position during a time when Austria faced multiple threats from enemy forces.
Written by AI on 2026-10-04, from this article's own text only (the story summary below draws on all the coverage).

AI analysis

Story summary

Carter Church, an AI engineer at SentinelOne, successfully decrypted a coded message from Napoleon Bonaparte to his general Auguste de Marmont using OpenAI’s GPT-6 Astra system after 217 years. The letter, sent by Napoleon's stepson Eugène, contained details about French and Austrian troop movements on the eve of war between France and the Habsburg Empire in 1809. The ciphered note had 1300 characters, including letters and symbols, and was a mystery until GPT-6 Astra transcribed it within six hours by employing simulated annealing techniques. This breakthrough highlights the potential of AI in solving complex historical puzzles beyond human capabilities.

Written for “Napoleon Code Cracked” on 2026-10-30, grounded in this article and the 1 other(s) covering the same event.

Story

📰 Napoleon Code Cracked
Technology · 2 article(s) covering the same event. See how they differ ↓

Compared with similar articles

This article reads unscored and hedges 12% of its claims. Each row says how that neighbour differs.
The Sydney Morning Herald
Hedges 1 of 20 claims Outlet record 61/100
How this article was measured signals, leaning charts, publisher record, byline, topics and claims

Signals How these are calculated →

Claims extracted
25
sentences that state something as happening or true
Uncertain
12%
3 of 25 hedged ("reportedly", "may", "according to")
Leaning
not political
takes no side on a contested political question
Publisher signals
68/100
Daily Mail's corrections and hedging, across everything collected from it. Not a measure of accuracy.
Outlets on this story
2
Technology
Same framing elsewhere
1
articles that frame the event the way this one does
Analyzed 2026-10-04 · how these are computed

How this is being covered How these are calculated →

Article leaning vs. publisher reliability
Source leaning vs. consistency

Publisher

Daily Mail · 8386 article(s) · 20 correction(s) detected
Running correction rate · 20 correction(s)

Who wrote this

Shivali Best
11 article(s) here · 1 carrying a prediction
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🔮 While the letter would have originally come with a key, this has long been lost – meaning the contents have been a mystery.
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Also by Shivali Best
Nothing else under this byline is closely related to this article, so these are simply their most recent.
All 11 articles by Shivali Best →

Topics

Astra Dalmatia French GPT-6 Astra Paris

Subjects

Church ORG · 4× Marmont PERSON · 4× Napoleon PERSON · 4× Auguste de Marmont PERSON · 3× Eugene PERSON · 3× French NORP · 3× Dalmatia GPE · 2× Napoleon Bonaparte PERSON · 2× OpenAI ORG · 2× Paris GPE · 2×

Narrative

What makes this impressive isn't actually the codebreaking, but that Astra completed the entire multi-modal workflow in six hours from a single image and goal,' he explained on X. A mysterious letter written by Napoleon Bonaparte has been decoded for the first time after more than 200 years On March 16, 1809, Napoleon wrote from Paris to his stepson, Eugene, asking him to send a letter to Auguste de Marmont – a friend of the Emperor, whose troops were positioned in Dalmatia, on the far side of the Adriatic.
framing: assertive · carried by 1 article(s) · first seen 2026-10-04
🔮 While the letter would have originally come with a key, this has long been lost – meaning the contents have been a mystery.

Claims (25 extracted, 3 hedged)

A mysterious letter written by Napoleon Bonaparte has been decoded for the first time in more than 200 years. asserted
letter → write → years
The letter was sent to French general Auguste de Marmont by Napoleon's stepson, Eugene, the Viceroy of Italy, in 1809. asserted
letter → send → 1809
The first line is written in French, but the 24 lines that follow consist of two-digit numbers, stray letters, and invented symbols. asserted
that → write → numbers
While the letter would have originally come with a key, this has long been lost – meaning the contents have been a mystery. asserted
contents → come → key
Now, Carter Church, an engineer at cybersecurity company SentinelOne, has cracked the code using AI. asserted
Church → crack → AI
'I used GPT–6 Astra to break an unsolved cipher to one of Napoleon's generals that had gone unread for 217 years. asserted
that → use → years
What makes this impressive isn't actually the codebreaking, but that Astra completed the entire multi-modal workflow in six hours from a single image and goal,' he explained on X. A mysterious letter written by Napoleon Bonaparte has been decoded for the first time after more than 200 years On March 16, 1809, Napoleon wrote from Paris to his stepson, Eugene, asking him to send a letter to Auguste de Marmont – a friend of the Emperor, whose troops were positioned in Dalmatia, on the far side of the Adriatic. asserted
troops → make → Adriatic
With Austrian territory between them and every other French army, Marmont would have been isolated if war came. asserted
war → isolate → them
The first line is in French, and reads: 'Vous avez dû recevoir, Monsieur le Général Marmont, mes lettres des 8, 14 et 20 courant.' This translates to: 'You must have received, General Marmont, my letters of the 8th, 14th, and 20th of this month. asserted
You → read → month
However, with the rest of the letter written in code, its meaning has been unclear. uncertain
meaning → write → code
To crack it, Mr Church turned to GPT-6 Astra – an AI model created by OpenAI. asserted
Church → crack → OpenAI
Over six hours, the bot was able to decipher the message. asserted
bot → decipher → message
'Astra cut the 1,202 by 1,836 plate into rows, read the signs, decided which of 175 hand–drawn marks were the same sign written twice, and only then began breaking the cipher,' Mr Church explained in a blog post. asserted
Church → cut → post
The letter lays out the location of every other French and allied army, and urges Marmont to 'not be intimidated' by his isolated position. asserted
letter → lay → position
'The Russians are marching against Austria, and the army [of] Friuli today numbers eighty thousand men,' it reads. asserted
it → march → men
'Add the Dalmatian corps, without counting the reserves being organised everywhere in the rear, and you see that Austria will be attacked at once on every side. ' asserted
Austria → add → side
She is consequently hastening toward her ruin. asserted
She → hasten → ruin
'When you receive the order to march, you must not allow yourself to be intimidated by a few troops or a gathering of rabble.' To crack it, Mr Church turned to GPT-6 Astra – an AI model created by OpenAI. asserted
Church → receive → OpenAI
Over six hours, the bot was able to decipher the message On 16 March 1809, Napoleon (pictured in painting) wrote from Paris to his stepson, Eugene, asking him to send a letter to Auguste de Marmont – a friend of the Emperor, whose troops were positioned in Dalmatia, on the far side of the Adriatic asserted
troops → decipher → Adriatic
According to Mr Church, the cipher itself wasn't actually difficult to crack. uncertain
cipher → accord → Church
However, he admits it would have taken humans much longer than the AI, which was able to whizz through it in just six hours. asserted
which → admit → hours
He added: 'The cipher itself isn't difficult, and cryptographers could have cracked this easily given the time/energy. uncertain
cryptographers → add → energy
'But, the work to transcribe, catalog, translate, then crack is involved and multi-disciplinary. asserted
work → transcribe → ?
Every field has an unsolved backlog of niche problems that specialists don't have the bandwidth to tackle. asserted
specialists → have → bandwidth
'The takeaway here is that the people shortening those lists will increasingly be outsiders who were simply curious.' asserted
who → shorten → lists
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