972Cyphersolver
…muler nous sommes obligez de ne pas abandonner ce poste ni ces lieux sans les ordres expres

BnF NAF 22736 · contributed by George Lasry · French

Abraham Duquesne to Seignelay, 25 September 1681; later letter in the same September correspondence

Abraham Duquesne
fromAbraham Duquesne
Marquis de Seignelay
toMarquis de Seignelay

Duquesne discusses negotiations with the Tripolins, the return of enslaved French subjects and captured ships, vessels suitable for use as fire-ships, treaty provisions and naval affairs. The later letter states the obligation to retain the position until express orders arrive and the hope of ending the campaign advantageously. Deciphered by George Lasry, working with ChatGPT Astra 6 and Anthropic Opus 5.5, in his BnF cipher research of October 2026: 751 elements, 743 identified (98.9%).

George Lasry · posted · updated

Method: key recovered based on adjacent plaintext · Extent: complete

Contributed by George Lasry (solution)

01 The letter

ShelfmarkBnF NAF 22736 · Duquesne, ff137r–138r and144v
SenderAbraham Duquesne
RecipientSeignelay
Date25 September 1681; later letter in the same September correspondence
LanguageFrench
Report status4/4 pages transcribed; 4/4 pages deciphered
Ciphertext751 elements, 743 identified (98.9%)

02 The key

97 codes

George Lasry’s reconstructed key table
George Lasry’s reconstruction of the key, as drawn in his report (p. 110). Image: George Lasry, BnF cipher research (10 Oct 2026); manuscript: Bibliothèque nationale de France, NAF 22736, Gallica btv1b10027296v view 276.

03 The decipherment

Manuscript lines with the cipher, from George Lasry’s report
The manuscript lines of the excerpt (f144v, first three cipher lines), from the report, p. 111. Image: George Lasry, BnF cipher research (10 Oct 2026); manuscript: Bibliothèque nationale de France, NAF 22736, Gallica btv1b10027296v view 276.

f144v, first three cipher lines

…muler nous sommes obligez de ne pas abandonner ce poste ni ces lieux sans les ordres expres

Translation. …we are obliged not to abandon this post or these places without express orders.

04 Plaintext and other sources

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

Interlinear plaintext
Interlinear plaintext on the cipher pages.

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.

06 Notes and corrections

Lasry's excerpt is fuller than the contemporary interlinear: he gives "ce poste ni ces lieux sans les ordres expres", the interlinear reads "ce poste sans des ordres expres". His reading of the codes may differ from the clerk's.

07 Sources