HISTORICAL ARTICLE SNAPSHOT — SUPERSEDED Captured for the public archive on 5 October 2026. This is an earlier, already-published article. Its claims and links reflect that version; subsequent corrections are in the current article: https://maxim-egorov.dev/research/desportes-1593/ The article text below is preserved exactly. It is not the full research apparatus. --- BEGIN PRESERVED ARTICLE TEXT --- --- title: "A Working Reconstruction of Desportes’s Letter of 22 July 1593" description: "Promises of help on the eve of Henri IV’s conversion: a partial reading using Tomokiyo’s published key, with lacunae preserved." preparedUtc: "2026-10-02T20:18:02Z" --- ## Promises of help on the eve of Henri IV’s conversion The reading, checks and editorial preparation used AI assistance. Paris, 22 July 1593. Henri IV’s conversion to Catholicism is three days away. The author of a letter attributed to Baudouin Desportes by the Bibliothèque nationale de France catalogue already sees his opponent’s intention to change faith drawing former enemies to his side. Continuing to resist on the strength of allies’ promises is becoming harder. To reject the prospect of peace, he writes, will take real action. Much of this letter to Pietro Aldobrandini is encrypted. The working reconstruction presented here makes it possible to follow the author’s arguments on both sides of the leaf, although folds, areas obscured by ink and unidentified signs leave substantial gaps. It uses Satoshi Tomokiyo’s previously published key. The result is a reading of a particular document and a verifiable explanation of how that reading was obtained. ## Which letter was read The source is held at the Bibliothèque nationale de France: **Français 3984, leaf 186, recto and verso**, images 347–348 in Gallica. The ending shows the signature *Desportes*, Paris and the date *xxij Juillet 1593*. Catalogue entry no. 88 supplies the author’s name, Baudouin Desportes, and the recipient, *monsignor don Pietro Aldobrandini*. The recipient’s personal name is not inferred from the courteous form of address on the leaf itself. [Official BnF record](https://archivesetmanuscrits.bnf.fr/ark:/12148/cc504266/cd0e20251) · [Recto](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f347) · [Verso](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f348) This matters for the scope of the study. The same collection contains other letters by Desportes, including a separate letter to Frachetta. Their contents cannot silently be added to leaf 186. Nor should the author be identified with the poet Philippe Desportes, or the catalogue’s Baudouin be replaced with Jacques: historical literature refers to several different Desportes. Ordinary handwriting and cipher alternate here. The opening explains why the author has written infrequently: a truthful account might offend other participants, while bad news might distress the pope. Desportes then turns to complaints, explanations of earlier decisions and a defence of his own reputation. This progression helps explain the letter’s political meaning, but does not by itself allow unread passages to be filled in. ## Why promises were no longer enough One of the clearest passages is on the recto, in lines M3–M4 of the working edition. Joining the physical line break gives:

IL FAUDROIT BEAUCOUP D EFFECTZ AUANT QUE DE NOUS FAIRE REIECTER LA PARENCE D UNE PAIX

In English translation: > It would take a great deal of real action before making us reject the prospect of peace. The French spelling follows the accepted reading. The expression about peace denotes its possibility or prospect; it does not say that peace has already been concluded. Spacing, punctuation and the English translation are editorial work. [Manuscript, recto](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f347) In the neighbouring lines, the author reproaches allies for promises that have already deceived his side. Earlier, he describes an army that remained at the frontier and withdrew after a single rumour. The code identifying whose army it was remains unresolved, so naming it on the basis of historical expectations would be premature. On the verso, the same argument returns in another form. V21–V22 expresses a willingness to accept a particular candidate as king, provided a way to protect him is shown. A lacuna remains between the parts of the sentence; the candidate’s name is unidentified. The repeated demand for effective protection, however, fits the contrast between promises and action on the recto. [Manuscript, verso](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f348) This is the central theme of the readable passages: the conditions under which the struggle can continue and a political settlement can be accepted. References to the House of Bourbon and the kingdom’s fundamental laws in L10–L11 show that the dispute also concerns the succession. The gaps still prevent a reconstruction of all the proposals, letters and negotiations to which Desportes refers. ## Three days before Saint-Denis In B6–M2, the author writes about choosing a king at a moment when the opponent is beginning to attract former enemies through his intention to become Catholic and is due to attend Mass on Sunday. Henri IV renounced Protestantism at Saint-Denis on Sunday, **25 July 1593**. The letter’s date and wording provide strong grounds for connecting this passage with him. This is a historical identification from context: Henri’s name has not been substituted for “the opponent” in the transcription. [Letter](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f347) · [Château de Pau museum on the events of 1593](https://chateau-pau.fr/node/591) Seen in this light, the letter records the anticipation of change. The author understands that removing the religious obstacle may reduce the number of people willing to resist Henri. He is not yet describing a ceremony that has taken place, and does not know its consequences. The letter also serves as a defence of the author’s conduct. Desportes recalls earlier warnings, explains his caution and anticipates criticism. His accusations show how he wanted to present the situation to Aldobrandini. Treating each of them as an independently established fact about his allies’ intentions would be a mistake. ## How the reading works Tomokiyo published the key to the Catholic League’s polyphonic cipher and described it through other documents. In this system, an ordinary sign permits two letters: for example, **A/N**, **B/O** or **G/T**. There are also separate signs for words, including *QUE*, *QUI* and *POUR*. Tomokiyo’s page lists the encrypted parts of leaf 186 as unread. Having a known key therefore does not supply a finished text of this particular letter. [Tomokiyo’s published key and study](https://cryptiana.web.fc2.com/code/mayenne.htm) The work is divided into several verifiable layers: 1. **Image and sign class.** The visible sign and its location on the original scan are recorded for each passage. 2. **Letter selection and word division.** A letter consistent with French and the context is selected from the permitted alternatives. A coherent phrase remains a hypothesis when the sign’s appearance is uncertain. 3. **Ordinary handwriting.** Unencrypted insertions are read separately. They cannot be presented as results of applying the key. 4. **Commentary and translation.** Historical identifications and the modern translation are kept separate from the letter reading. Several passages underwent separate repeat checks of sign classes without showing the checker the proposed phrase. One such check revealed a disagreement at M8:37: the sign may belong to F/S or G/T. Instead of the syntactically convenient *PEUT*, the edition leaves a gap. These checks apply to the specified passages; they cannot certify every line of the letter. Software checks whether the selected letters match the recorded classes. This does not establish that the signs were correctly identified in the first place, or that the resulting text is the only possible reading. No percentage of “decipherment accuracy” is calculated from the number of filled positions. ## What a neighbouring document helped clarify A primary control is particularly useful: a decipherment contemporary with the letters on leaf 185, and the corresponding encrypted text on leaf 188v. They allow individual signs to be compared with the words written beside them. This is a different document: its letter is dated 22 July, but has a postscript of 26 July. It cannot be used in its entirety as evidence of the situation on 22 July. [Control decipherment, leaf 185](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f345) · [Encrypted control, leaf 188v](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f352) The comparison provides strong support for two groups of signs in the letter under study: - The Ω-like sign at **B1:53 and V21:11** corresponds to the control sign annotated *du Mayne*. There are therefore strong grounds for relating the reference to patience in V21 to Mayenne. - The g-like sign at **B2_prefix:11 and B5:22** corresponds to the annotation *legat*, meaning “legate”. The basis here is the shape of the signs and the annotated primary control. The full verbal form of the codes, articles and the preceding title sign remain separate questions. The identity of the nephew mentioned is also unresolved. In the working transcription, these signs retain their earlier provisional labels; the proposed expansions belong to the commentary. X2, X3 and X4 are local to their respective blocks. The recurrence of a label elsewhere proves nothing by itself. In particular, not every X4 can be expanded as “legate”. The tentative letter reading **[MATEUCI?]** also retains its question mark. For the historical narrative, it is enough for now to leave it as an unidentified name, without turning a plausible biography into evidence for the letters on the leaf. ## What was already known The novelty of this work needs a narrow definition. Tomokiyo’s key has been known since 2017; his page records an update in 2023. In the examined public attempt by the *cyphersolver* project in 2026, the target letter also remained unread. These are facts about two particular works, not proof that all earlier readings are absent. [Tomokiyo](https://cryptiana.web.fc2.com/code/mayenne.htm) · [cyphersolver materials](https://github.com/dbourdeau/cyphersolver/blob/main/targets/sega1593/NOTES.md) A bounded search found no earlier printed publication of the decipherment of this exact leaf 186. The examination covered OCR texts and relevant passages in four editions: L’Épinois’s *La Ligue et les papes* (1886), volume V of *Négociations diplomatiques de la France avec la Toscane* (1875), volume I of Perrens’s *L’église et l’état en France* (1872), and Bernard’s *Procès-verbaux des États généraux de 1593* (1842). Relevant pages in L’Épinois were also checked against the scans. OCR errors, variants of names, translations and publications outside this selection remain substantial limitations. This search establishes neither that the letter was unpublished nor global priority. General criticism of Spanish policy and the legate has also long been known from neighbouring letters. On page 598, L’Épinois discussed it with references to leaves **184 and 177**, rather than 186. The significance of this result therefore cannot be reduced to the discovery of previously unknown anti-Spanish sentiment. [L’Épinois, checked page 598](https://archive.org/download/laligueetlespap00lepgoog/page/n563.jpg) The possible addition to knowledge lies in the precise wording of this letter to Aldobrandini, the order of its arguments, the conditions for agreement and the way the author defends his position. These details can now be discussed by comparing the text with the images and preserving its gaps. ## How to check the result The research materials prepared for this work include a full working French reading, a continuous Russian translation with commentary, and a package of verification materials. The package contains source images, passage coordinates, sign classes, accepted letter choices, a list of lacunae and records of separate repeat checks. These supplementary materials are not included in this publication. The manuscript and published key are available through the links in the article; the English translation of the quoted passage is provided above. Checking a particular passage starts with its identifier, such as M3–M4 or V21–V22. The corresponding area can then be found on the scan, the visible sign checked and compared with the key, and only then the selected letter and the phrase’s meaning assessed. Special signs should also be checked against the neighbouring control document. The package also contains a script that checks the compatibility of accepted letters with recorded classes and verifies file integrity through checksums. These checks passed when rerun during preparation of the article. The script checks the internal consistency of the records; palaeographic reading remains the researcher’s task. A gap in the edition may mark an indistinct sign, an unknown code or an area obscured by a fold and ink. It does not always signify lost paper or a known number of missing letters. Words cannot therefore be completed across such places merely to produce smooth French prose. ## What the letter contributes In the readable passages, Desportes consistently demands grounds for trust: help, protection and sufficiently clear guarantees. At the same time, he tries to show that he foresaw the danger and acted reasonably. Three days before Henri IV’s conversion, this is a particularly telling witness to uncertainty within the Catholic camp. The working reconstruction brings the specific words of this letter back into the discussion. Its value will depend on further checks: whether disputed signs can be clarified, connections between damaged sentences restored, and an earlier text of the document found. For now, the accurate description of the result is **a reproducible partial reading of a known letter using a published key, with lacunae preserved and explicit limits of confidence**. ## Sources and checked literature 1. BnF, Département des Manuscrits, Français 3984, no. 88, f. 186r–v. [Catalogue](https://archivesetmanuscrits.bnf.fr/ark:/12148/cc504266/cd0e20251), [186r](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f347), [186v](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f348). 2. BnF, Français 3984, control materials. [Decipherment on f. 185](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f345), [encrypted original on f. 188v](https://gallica.bnf.fr/ark:/12148/btv1b9060633d/f352). 3. Satoshi Tomokiyo. *A Polyphonic Substitution Cipher of the Catholic League (1592–1593).* First published 14 May 2017; recorded update 29 June 2023. [Article and key](https://cryptiana.web.fc2.com/code/mayenne.htm). 4. dbourdeau. *cyphersolver*, materials on the *sega1593* target, session of 17 September 2026. [Research notes](https://github.com/dbourdeau/cyphersolver/blob/main/targets/sega1593/NOTES.md). 5. Musée national du château de Pau. Materials on Henri IV and the path to civil peace. [Historical account](https://chateau-pau.fr/node/591). 6. Henri de L’Épinois. *La Ligue et les papes.* Paris: Victor Palmé, 1886. [Digitised edition](https://archive.org/details/laligueetlespap00lepgoog), [scan of p. 598](https://archive.org/download/laligueetlespap00lepgoog/page/n563.jpg). 7. Abel Desjardins, Giuseppe Canestrini. *Négociations diplomatiques de la France avec la Toscane.* Vol. V. Paris: Imprimerie nationale, 1875. [Digitised edition](https://archive.org/details/bub_gb_3yEMAQAAMAAJ). 8. François-Tommy Perrens. *L’église et l’état en France sous le règne de Henri IV et la régence de Marie de Médicis.* T. I. Paris: A. Durand et Pedone-Lauriel, 1872. [Digitised edition](https://archive.org/details/lgliseetltat01perr). 9. Auguste Bernard. *Procès-verbaux des États généraux de 1593.* Paris: Imprimerie royale, 1842. [Digitised edition](https://archive.org/details/procsverbauxde37franuoft).
## Abstract This article presents a partial working reconstruction of Baudouin Desportes’s cipher letter to Pietro Aldobrandini, written in Paris on 22 July 1593 and preserved in BnF Français 3984, f. 186r–v. It applies Satoshi Tomokiyo’s previously published polyphonic key and distinguishes image-level transcription, contextual letter selection, ordinary handwriting, and historical interpretation. Contemporary controls on f. 185 and f. 188v strongly support specific signs referring to Mayenne and the legate; other names and substantial gaps remain unresolved. The readable passages stress the need for effective support and credible guarantees on the eve of Henri IV’s conversion. No earlier printed plaintext of this exact letter was located in a bounded search. This is neither a claim to a new cipher key nor a claim of global priority. The reconstruction and editorial preparation used AI assistance.