King Joseph's cipher letter, deciphered

In 1969 an officer published in the Revue historique des Armées the photograph of a fully enciphered dispatch kept in the French National Archives and presented as a letter from Marshal Berthier to Napoleon, dated 22 December 1812. Its 325 numbers read with the Great Cipher of 1812, the code of the French armies in Spain. The text that comes out is not Berthier's, who was then in Prussia with the remnants of the Grande Armée: the writer is, in all likelihood, King Joseph, the Emperor's brother, writing from Madrid.

“I have had no news from Your Majesty since your departure from Paris; I have had no direct news from France since the letters of the Minister of War of the fifth of October.” — the first deciphered lines.

An independent re-reading by Brice Dudout, carried out with Claude (Anthropic). The key and the writer were first identified by Ilia Chirtulov (reported on Cryptiana on 12 October 2026).

Top of page 3 of the dispatch: in the margin “Duplicata, Chiffre du Prince de Neufchâtel” and “La Primata a été déchiffrée”, in the centre “Sire,”, then the lines of numbers 918.1045.1100.493… — Page “(3)” of the dispatch, with the marginal notes “Duplicata · Chiffre du Prince de Neufchâtel” (duplicate, cipher of the Prince of Neuchâtel) and “La Primata a été déchiffrée” (the first copy has been deciphered). Plate from J. Vilcoq, *Revue historique des Armées*, 1969, no. 4, after the original in the Archives nationales; digitised by Persée [1].

325cipher groups on 22 lines: the whole published part of the letter

207distinct values, read one by one in the deciphering table of the Great Cipher of 1812

0 / 1,000shuffled tables that give a text as French as the real table

8groups of the online transcription corrected from the 1969 photograph

1sister letter printed in 1854 (Joseph to the Minister of War, 23 December 1812) that says the same things

Article 1 · Context

Madrid, December 1812: a king without news

While the Grande Armée dies in Russia, Joseph Bonaparte holds Spain with armies that only half obey him and couriers that the guerrillas intercept. What the letter says, and what Napoleon will do about it.

Read the article →

Article 2 · Method

Finding the key: from unknown codes to the Great Cipher of 1812

The tables tried without success, the photographs of the 1812 table, the 207 values read, the permutation control, the re-reading of the 1969 plate, and the sister letter printed by Du Casse.

Read the method →

Text

The letter, line by line

The 325 numbers, the value of each in the table, the reading, the uncertain passages, then the running French text and its English translation.

See the letter →

Pipped at the post

Ilia Chirtulov was the first to establish that this cryptogram reads with the Great Paris Cipher and that the writer is most likely King Joseph: his result, obtained with the help of Claude (Anthropic), was received by S. Tomokiyo on 4 October 2026 and reported on Cryptiana on 12 October [3]. We reached the same result independently on 12 October, without having seen that note: we found it that same evening, while checking the links of this site. Congratulations to him.

This site adds: the complete reading, line by line, with the value of each group in the table; a re-reading of the cipher on the 1969 plate, which corrects 8 groups of the online transcription; a permutation control; and a sister letter printed in 1854 [7] that confirms the content and the writer. The letter was also deciphered at the time (“La Primata a été déchiffrée”): its plain text may survive in the National Archives.