J King Joseph's cipher letter

References

Sources and credits

The numbers match the note calls in the articles. Web pages were consulted on 9 and 12 October 2026.

This work starts from the cryptogram listed by S. Tomokiyo on his site Cryptiana [2, 3], devoted to the history of cryptography, whose pages on Napoleon's great ciphers guided the whole search (users of the Great Cipher, codes of 1812–1813, references to Vilcoq).

It also relies on the list of unsolved ciphers and the notes published by Daniel Bourdeau [4] (CC BY 4.0), on the photographs of the Great Cipher table published by Jean-François Bouchaudy [5], and on the transcriptions of Imperial codes by Tant, published by the ARCSI [6].

The key (the Great Paris Cipher) and the writer (King Joseph) were first identified by Ilia Chirtulov, with the help of Claude (Anthropic), as reported by S. Tomokiyo [3].

Thanks to all.

The cryptogram

  1. Lieutenant-Colonel J. Vilcoq, “Le chiffre sous le Premier Empire”, Revue historique des Armées, 25th year, no. 4, 1969, pp. 22-27 and plates, DOI 10.3406/rharm.1969.8686, digitised by Persée. Plate “Correspondance datée du 22 décembre 1812 du maréchal Berthier, Prince de Neufchâtel, à l'Empereur (Archives Nationales)”.
  2. S. Tomokiyo, “Great Ciphers of Napoleon's Grande Armée”, Cryptiana (section “Napoleon-Berthier Code (December 1812)”, Great Paris Cipher, codes of 1813).
  3. S. Tomokiyo, list of unsolved ciphers, Cryptiana, entry “Encoded Letter from Berthier to Napoleon (1812) — Solved”, updated 12 October 2026: identification of the Great Paris Cipher and of King Joseph by Ilia Chirtulov (result received on 4 October 2026).
  4. Daniel Bourdeau, “Unsolved Historical Ciphers — Working Notes, Solutions and Corrections” and repository dbourdeau/cyphersolver (target “Berthier → Napoleon; letter to Marmont”, folder targets/napoleon). CC BY 4.0.

The key

  1. Jean-François Bouchaudy, “The codebooks of Napoleon I”: photographs of the deciphering table of the code of the 1812 Spanish campaign (groups 1-1400), Service historique de la Défense, “B n° 30”.
  2. Tant, transcriptions of Imperial codes (“unknown code” 1 to 3, “Napoleonic code” I to III, small cipher of 1813), ARCSI, arcsi.fr/doc/Tant (nos. 367-369, 372-379, 386).

Context and verification

  1. A. Du Casse (ed.), Mémoires et correspondance politique et militaire du roi Joseph, vol. IX, Paris, Perrotin, 1854, Gallica: Joseph to Clarke, Madrid, 10 and 23 December 1812 (pp. 121-126); Joseph to Suchet, 23 February 1813.
  2. Correspondance de Napoléon Ier, vol. 24, Paris, 1868, Internet Archive: no. 19561 (to Clarke, 9 February 1813) and index (“Espagne”, “Reille”).
  3. Archives nationales, Secrétairerie d'État impériale. Guerre (AF/IV/1590 à 1670), inventory by N. Gotteri, FRAN_IR_003827 (King Joseph's correspondence: AF/IV/1633, plaquette 2; AF/IV/1634, plaquette 1).
  4. A. Chuquet, 1812. La guerre de Russie. Notes et documents, 3rd series, Paris, 1912: Berthier's letters to Napoleon of December 1812 (text used as the language reference for the control).

Related work

  1. C. Church, “Breaking the Marmont Cipher, 1809” (September 2026): decipherment of the other cryptogram reproduced by Vilcoq [1], the letter to General Marmont, in a different cipher.

Tools

Reading the photographs, locating the grid, transcribing the entries, decoding, permutation control and comparison of texts: Brice Dudout with Claude (Anthropic). Data and scripts: repository bdudout/joseph-napoleon.