Jacques Vergier to Monseigneur, probably Jérôme de Pontchartrain, 10, 20, 26, 29 and 30 March 1696; 6 April 1696? (BnF Clairambault 1108)

01 The letter

Shelfmark	BnF Clairambault 1108
Sender	Jacques Vergier
Recipient	Monseigneur, probably Jérôme de Pontchartrain
Date	10, 20, 26, 29 and 30 March 1696; 6 April 1696?
Language	French
Report status	17/17 pages transcribed; 12/12 cipher pages deciphered
Ciphertext	1,212 elements, 1,209 identified (99.8%)

02 The key

152 codes: 31 letter codes, 116 nomenclature entries, 5 nulls

George Lasry’s reconstructed key table — George Lasry’s reconstruction of the key, as drawn in his report (p. 71). Image: George Lasry, BnF cipher research (10 Oct 2026); manuscript: Bibliothèque nationale de France, Clairambault 1108, via Gallica.

03 The decipherment

Manuscript lines with the cipher, from George Lasry’s report — The manuscript lines of the excerpt (f249v), from the report, p. 72. Image: George Lasry, BnF cipher research (10 Oct 2026); manuscript: Bibliothèque nationale de France, Clairambault 1108, via Gallica.

f249v

…dit seulement qu’il croyoit, et je trouve que c’est avec assez de raison, que l’affaire est à present presque impraticable sur la coste de Kent, à cause des forces que le Prince d’Orange a mises de ce costé-là. Et qu’il seroit à present necessaire de tenter le debarquement dans la province d’York, où sont presque tous les haras d’Angleterre, et où par consequent on trouveroit les chevaux necessaires pour l’armée, ou bien dans une des provinces de l’Ouest.

Translation. …said only that he thought—and with good reason, I believe—that the enterprise is now almost impracticable on the coast of Kent because of the forces the Prince of Orange has stationed there. It would now be necessary to attempt the landing in Yorkshire, where almost all England’s stud farms are situated and where the horses needed for the army could consequently be found, or in one of the western provinces.

04 Plaintext and other sources

Where a decipherment or clear copy already existed, as George Lasry gives it:

Interlinear plaintext: Historical interlinear plaintext in the six letters, ff247r–251v,256v–257v,260v– 262r.

05 Our check

This result is George Lasry’s. This project did not re-solve the cipher: it checked one sample against the Gallica image and recorded what it found.

Batch A. Image checked: https://gallica.bnf.fr/ark:/12148/btv1b90009665/f263.item
Folio matches the report: yes; cipher present: yes
What we checked: f260r "Boulogne ce 30 mars 1696", Monseigneur, signed Vergier (facing leaf); canvas f255 shows f251v numeric codes with interlinear ("277 14 176 143 259 186 50 ..." = "que je scache aussi qu ... ", "208 17 226 34 301 197 30 289" = "mon nouveliste"), confirming interlinear plaintext; f249v excerpt not compared symbol by symbol
Verdict: partly confirmed (method key recovered based on adjacent plaintext, extent complete). The check is a sample, not a re-solution.
Notes: Slug says 1690 but every letter is 1696. Canvas f255 shows a letter "a Dunkerque ce 16e avril 1696" (f252r) - his "6 April 1696?" is probably 16 April. Interlinear decipherments throughout.

06 Notes and corrections

Folder renamed from the report's slug vergier1690: every letter is dated 1696. The report's "6 April 1696?" is probably 16 April (f252r, "a Dunkerque ce 16e avril 1696").

07 Sources

George Lasry, with ChatGPT Astra 6 and Anthropic Opus 5.5, BnF cipher research, 10 October 2026 (sent to Daniel Bourdeau on 13 October 2026 for publication here), p. 71; his other items are listed on his contributor card.
The working folder: targets/vergier1696/ (his entry as extracted from the report, our spot-check, profile.json).