01 The letter
| Shelfmark | BnF Clairambault 1067 |
|---|---|
| Sender | Brienne |
| Recipient | Queen of Poland |
| Date | Compiègne, 19 May 1646 |
| Language | French |
| Report status | 6/6 pages transcribed; 4/4 cipher pages deciphered |
| Ciphertext | 350 elements, 349 identified (99.7%) |
02 The key
88 symbols/codes, 25 letter signs, 61 in nomenclature, 2 nulls
03 The decipherment
f226v
Le mien a esté qu’en la pluspart des affaires du monde le souverain conseil est de gaigner temps, et que ce seroit assez tost respondre aux ministres de Monsieur de Mantoue quand ilz renouvelleroient leurs instances; et peut estre qu’ayant presentement diverses choses à poursuivre ilz pourront s’oublier de celle-là, et ainsi le titre du gouvernement de Nivernois se trouvera fortiffié d’une possession maintenue depuis son absence du Royaume.
Translation. My view was that in most affairs of the world the wisest course is to gain time, and that it would be soon enough to answer Monsieur de Mantua’s ministers when they renewed their requests. Perhaps, having various matters to pursue at present, they will forget this one; thus the title to the government of Nivernois will be strengthened by possession maintained since his departure from the kingdom.
04 Plaintext and other sources
Where a decipherment or clear copy already existed, as George Lasry gives it:
- Interlinear plaintext
- Historical plaintext above cipher rows on PDF50–53, ff226–227 and continuation; letter ends at PDF55.
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/btv1b90008551/f48/full/1600,/0/default.jpg
- Folio matches the report: yes; cipher present: yes
- What we checked: f226r: "Madame", clear text then cipher row with interlinear "que je communicasse sa despesche a la Reyne"; f226v show-through shows interlinear "...le souverain conseil est de gaigner temps..." as in his excerpt; codes not decoded independently
- Verdict: confirmed (method key recovered based on adjacent plaintext, extent complete). The check is a sample, not a re-solution.
- Notes: Fully interlined by a contemporary hand; 99.7% identified. Recipient Queen of Poland (Marie-Louise Gonzague) fits the Nevers/Mantua content.
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. 99; his other items are listed on his contributor card.
- image checked in the spot-check
- The working folder:
targets/brienne1067/(his entry as extracted from the report, our spot-check,profile.json).