Raimond Phélypeaux d’Herbault to Bullion, 29 July 1625 (BnF Français 3944)

01 The letter

Shelfmark	BnF Français 3944
Sender	Raimond Phélypeaux d’Herbault
Recipient	Bullion
Date	29 July 1625
Language	French
Report status	1/2 pages transcribed; 1 more in part; 2/2 cipher pages deciphered
Ciphertext	375 elements, 366 identified (97.6%)

02 The key

81 symbols/codes: 51 letter signs, 30 syllable or word codes.

George Lasry’s reconstructed key table — George Lasry’s reconstruction of the key, as drawn in his report (p. 90). Image: George Lasry, BnF cipher research (10 Oct 2026); manuscript: Bibliothèque nationale de France, Français 3944, Gallica btv1b9059448p view 197.

03 The decipherment

Manuscript lines with the cipher, from George Lasry’s report — The manuscript lines of the excerpt (f99r, three complete cipher rows), from the report, p. 91. Image: George Lasry, BnF cipher research (10 Oct 2026); manuscript: Bibliothèque nationale de France, Français 3944, Gallica btv1b9059448p view 197.

f99r, three complete cipher rows

croions que les forces presentes des [Ennemis] et les considerations de M. de Savoye pour la conservation de ses estats nous imposeront une loy assez absolue pour ce regard

Translation. We believe that the enemy’s present forces and Monsieur de Savoy’s concern for preserving his states will impose a fairly absolute rule on us in this respect.

04 Plaintext and other sources

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

Interlinear plaintext: Historical interlinear plaintext on the same letter, ff99r–v.

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 B. Image checked: https://openapi.bnf.fr/iiif/image/v3/ark:/12148/btv1b9059448p/f197/full/1600,/0/default.jpg
Folio matches the report: yes; cipher present: yes
What we checked: f99r 3 cipher rows: contemporary interlinear "croions que les forces presentes des Ennemis et les considerations de M. de Savoye pour la conservation de ses estatz nous imposeront une loy assez absolue pour ce regard" = his excerpt verbatim
Verdict: confirmed (method key recovered based on adjacent plaintext, extent complete). The check is a sample, not a re-solution.
Notes: Clear text + cipher; 97.6% identified, 2/2 cipher pages. Signed letter, 1625 Valtelline/Savoy context consistent.

06 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. 90; his other items are listed on his contributor card.
image checked in the spot-check
The working folder: targets/herbault1625/ (his entry as extracted from the report, our spot-check, profile.json).