Charles of Egmond to the grand master of France

At a glanceCiphertext-only break · complete

The letter: Charles of Egmond, duke of Guelders, to the grand master of France, from Arnhem on the apparent date 18 July (no year recovered). He says that obeying the king’s commands made him enter the war, and asks for continuing support and for help for his ambassador, the commander of Saint John.
Where: BnF français 3015 no. 8, f. 16 (Gallica btv1b9060086g, views 27–28). The catalogue called it an entirely ciphered letter with a ciphered address.
The cipher: A French substitution of sixteen lines, two raised insertions and the address, with many null signs (tall looped f forms, small circles) and paired arches for r.
How it was read: George Lasry recovered the key in 2023 (cryptiana GL.htm §2). Here it was recovered again from the ciphertext alone, from a new transcription, and Lasry’s key was found only afterwards. It rests on internal consistency, not yet checked symbol by symbol against his.
What it says: The address reads “A mon bon cousin / Monsieur le grant maistre / de France”. All of the body, address and both insertions decrypt.
Still open: The year and the recipient’s personal name; a few minor glyph uncertainties (the x in lextreme, the ink-heavy u in the date).
Credit: Key first recovered by George Lasry (2023).

01 The manuscript

The BnF catalogue places item 8 at folio 16. Gallica view 27 contains the body; view 28 contains the address. The clear closing and signature identify Charles. The separate letter at folio 24, views 39–40, is dated 3 April 1537 and also addresses the grand master, but is not a clear copy of this cipher. Its year cannot be transferred to this letter.

Sixteen lines of Egmond’s cipher with insertions above lines seven and fifteen — The complete cipher block, Gallica view 27. The full page also has a clear closing and CHARLES signature. Image: Bibliothèque nationale de France, fr. 3015 no. 8 (f. 16), via Gallica (btv1b9060086g, view 27).

02 The French plaintext

Spaces and capitals are editorial; u/v are left as u in the cipher transcription. Braces mark raised insertions. Square brackets mark the blotted sign interpreted as u. All values are inferred (I), with the doubts below graded M. Unusual spellings and the repeated “en ce / ce faisant” are preserved.

Line	Literal working reading
01	Mon cousin pource que sueis aduerti que donnes faueur
02	a uous possible au bien de mes affaires uous ai bien
03	uouellu faire la presente pour uous prier uoulloir
04	continuer pour laduenir cosidere lextreme necessite
05	la ou pour le present me trouue pour auir obei aulc
06	commandemens du roi lequel est cause que suis entre en
07	ceste guerre comme plus amplement {entenderes} par le commandeur
08	de sainct Iehan mon ambassadeur auquel ai donne charge
09	uous communiquer le tout il uous plaira lui
10	donner assistence telle quil lui sera besoing
11	et le croire en ce quil uous dira de par moi en ce
12	ce faisant me obligeres de plus en plus a uous
13	ce scet nostre seigneur auquel apres
14	mestre recommande a uostre bonne grace prie
15	uous auoir en {sa} garde darnhem ce dih[u]itieme de
16	iuillet

Clear closing, abbreviation expanded: Le tout v[ost]re bon cousin. Signature: CHARLES.

Address: A mon bon cousin / Monsieur le grant maistre / de France.

Three-line ciphered address to the grand master of France — The address, Gallica view 28: A mon bon cousin / Monsieur le grant maistre / de France. Initial and final nulls carry no words. Image: Bibliothèque nationale de France, fr. 3015 no. 8, address, via Gallica (btv1b9060086g, view 28).

03 Meaning in English

My cousin, having been informed that you give all possible support to my affairs, I wished to write and ask you to continue in the future, considering the extreme need in which I now find myself after obeying certain commands of the king, which caused me to enter this war. You will learn more fully from the commander of Saint John, my ambassador, whom I have instructed to communicate everything to you. Please give him such assistance as he needs and believe what he tells you on my behalf. By doing this you will oblige me increasingly to you, as our Lord knows. Having commended myself to your good grace, I pray that he keep you in his protection. From Arnhem, this eighteenth day of July [year absent].

This translates the apparent sense, not every literal anomaly. “Certain” interprets the unexpanded aulc; “eighteenth” interprets dih[u]itieme. The cipher gives titles, not the personal names of the recipient or ambassador.

04 How the key was recovered

Short French, German and Italian substitution probes on rough transcriptions gave no reliable decryption. Extending the transcript to all sixteen lines gave French fragments under a five-gram model. Image comparison then corrected compound signs and nulls: the paired looped stems labelled DD give s, and the paired arches CE give r. Tall looped f forms, small circles and several other shapes are nulls. Early drafts had confused m/n zigzags, seven/b with corner/f, and angular u with a plain cross/g.

The address and body share letter values and null behaviour. Their coherent decryptions cross-check each other, but are not independent known plaintext. A synthetic 180-letter French substitution control was recovered exactly by the probe; it checks the solver implementation only. The searches recorded in the notes found no earlier decipherment, but one existed. George Lasry had recovered the key in 2023. His reconstructed key for the Duke of Guelders’ cipher (BnF fr. 3015) is published in section 2 of S. Tomokiyo’s “George Lasry’s codebreaking”. It notes that many symbols in the ciphertext are needlessly doubled. The work on this page is therefore an independent re-solution. It has not yet been checked symbol by symbol against Lasry’s table.

The final body transcript contains 726 labelled signs, including both insertions; the address has 48. The body uses 27 label names, including variants of u and a special label for the blotted occurrence. This is a transcription inventory, not 27 proven distinct historical characters.

Replay labels and inferred values

These labels are research identifiers, not facsimile glyphs. Shape descriptions and occurrence corrections are in the repository.

Label	Value
`X`	null
`F`	null
`O`	null
`S`	m
`H`	o
`Z`	n
`T`	c
`A`	u
`DD`	s
`P`	i
`B`	p
`CE`	r
`Q`	e
`I`	q
`V`	a
`K`	null
`R`	t
`L`	f
`+`	u
`8`	l
`W`	d
`G`	h
`Y`	b
`J`	g
`U`	null
`EX`	x
`A_blotted`	[u]

python targets/egmond/decode_audited.py replays every main-line token and both insertions, checks their anchors and checks that the word-divided edition contains exactly the replayed letters. This guards transcription-to-edition fidelity; it is not independent proof of the inferred key.

Raised cipher insertion read as entenderes — “Entenderes”, inserted after “amplement” in line 7. The small e after t overlaps a descender from the preceding line. Image: Bibliothèque nationale de France, fr. 3015 no. 8 (f. 16), line 7, via Gallica (btv1b9060086g, view 27).

05 Uncertainties and limits

M, line 4: x in lextreme is assigned to a small sign with its bar extending left from the upright. Native-image inspection distinguishes it from the plain cross/g, but its value is supported by one occurrence and context.
M, line 15: the u in dih[u]itieme is ink-heavy. The decryption points to 18 July; no year is present. The catalogue’s tentative 1520s label is not established by this decipherment.
M, insertion 7: the small e after t overlaps another line’s descender.
I/M: several m/n zigzags are distinguished partly by context. All main lines were inspected, but this remains an inferred key without an independent historical control.
The literal forms sueis, uouellu, cosidere, auir, aulc and the repetition en ce / ce faisant survive native-resolution re-inspection. They may reflect spelling, abbreviation, enciphering slips or residual transcription error. The edition does not choose silently between those possibilities.
No personal names are substituted for “grand master of France” or “commander of Saint John”. A complete year and the precise campaign remain unestablished.
Prior solution. Lasry recovered the key in 2023 (see How the key was recovered). The next check is to compare his key with the values inferred here.

Small left-bar sign before t in lextreme — The left-bar sign taken as x, followed by the taller two-bar t sign, a null circle and paired arches r. Image: Bibliothèque nationale de France, fr. 3015 no. 8 (f. 16), line 4, via Gallica (btv1b9060086g, view 27).

Ink-heavy sign in dihuitieme and the following date letters — The date detail: h, the ink-heavy [u], i, t, i, e, m, e, followed by de. The preceding letters di are partly outside this crop. Image: Bibliothèque nationale de France, fr. 3015 no. 8 (f. 16), via Gallica (btv1b9060086g, view 27).

Full texts

The transcription and the decryption of every document on this page, so that the reading can be used and checked. Short files are shown here; all are in the repository.

Letter body, f. 16 (16 lines and two insertions)

Charles of Egmond, duke of Guelders, writes from Arnhem on 18 July (year absent) to his cousin the grand master of France: having obeyed the king's commands he has entered the war and is in extreme need; he asks for continued support and credence for his ambassador, the commander of Saint John.

Transcription

body_complete_tokens.txt

X F O S H X Z T H F A DD P Z B O H A CE T Q X I A Q DD A Q P DD V W K A Q CE R P I A Q O W H Z X Z Q DD L V A Q + CE V A F H A DD B H O DD X DD P Y 8 Q V A Y P Q O Z W Q X S Q DD V L O L V P CE Q DD + H O + DD V O P Y P Q Z X + H A Q 8 O 8 + L V P CE Q 8 V B CE Q X DD O Q Z R Q B H F + CE + H + DD B O CE P X Q CE + H A 8 O 8 H P CE T H Z R P Z + Q CE B H F + CE 8 V W K A Q U Z P CE T H O DD F P W Q CE Q 8 Q EX R O CE Q X S Q Z Q T Q DD U DD P R Q 8 V H + B H + CE 8 Q B CE Q DD Q Z R S Q R CE H + A Q B H F + CE V + P CE H Y Q P V + 8 T O T H S U S V Z W F Q S Q Z DD W + CE H P 8 Q F I A Q 8 Q DD R T V A DD Q I A Q O DD A P DD O Q Z R CE Q U Q Z T Q DD R Q J O + Q CE CE Q T H S O S Q B 8 A DD V S B 8 Q S Q Z R B V CE 8 Q T H S U S V Z W Q + CE W Q DD F V P Z T R P Q O G V Z F S H Z V S Y V DD O DD V W Q + CE V + I A Q 8 V P F W H Z X Z Q T G V CE J Q + H F A DD T H S O S A Z P F I A Q CE 8 Q K R H + R P 8 O + H F A DD B 8 V P CE V 8 A P X W H Z O Z Q CE V DD F DD P DD R Q Z T Q R O Q 8 F 8 Q I + P 8 8 + P F DD Q O CE V Y Q DD H P Z J K Q R 8 Q O T CE H P CE Q Q Z T Q I + P 8 + H O + DD W P CE V W Q O B V CE F S H P K Q Z O T Q X T Q F L V P DD V Z R S Q O H Y 8 P J Q F CE Q DD W Q O B 8 + DD Q Z K B 8 + F DD V + H + DD X T Q K DD T Q R F Z H DD F R CE Q DD Q P J Z F Q + CE O V + I A Q 8 V F B CE Q DD S Q O DD R CE F Q CE Q T H S X S V Z W Q V + H DD R CE Q Y H O Z F Z Q J CE V T Q B CE P Q F + H A DD V + H P CE F Q Z O J V CE K W Q W V F CE O Z G Q S T Q O W P G A_blotted P R P Q S Q W Q O P F A P 8 O 8 Q R Q Z R Q Z W Q CE Q DD DD V

Decryption

READING.md

# Charles of Egmond to the grand master of France

Status: read, with minor glyph uncertainties and literal anomalies retained.

Source: BnF français 3015, no. 8, folio 16. [Body, Gallica view 27](https://gallica.bnf.fr/ark:/12148/btv1b9060086g/f27.item); [address, view 28](https://gallica.bnf.fr/ark:/12148/btv1b9060086g/f28.item).

## Diplomatic working reading

All values are inferred (I), not taken from an archived key or known plaintext.
Doubtful glyph identifications are M as detailed below. Spaces and capitalization
are editorial. Braces contain raised insertions. Square brackets mark the
ink-heavy sign interpreted as u. Peculiar spellings and repetitions are retained.
The word-divided lines are checked automatically against the token replay.

01. Mon cousin pource que sueis aduerti que donnes faueur
02. a uous possible au bien de mes affaires uous ai bien
03. uouellu faire la presente pour uous prier uoulloir
04. continuer pour laduenir cosidere lextreme necessite
05. la ou pour le present me trouue pour auir obei aulc
06. commandemens du roi lequel est cause que suis entre en
07. ceste guerre comme plus amplement {entenderes} par le commandeur
08. de sainct Iehan mon ambassadeur auquel ai donne charge
09. uous communiquer le tout il uous plaira lui
10. donner assistence telle quil lui sera besoing
11. et le croire en ce quil uous dira de par moi en ce
12. ce faisant me obligeres de plus en plus a uous
13. ce scet nostre seigneur auquel apres
14. mestre recommande a uostre bonne grace prie
15. uous auoir en {sa} garde darnhem ce dih[u]itieme de
16. iuillet

Clear closing, with the abbreviation expanded: “Le tout v[ost]re bon cousin”.
Signature: CHARLES.

Address: “A mon bon cousin / Monsieur le grant maistre / de France”.

## Meaning in modern English

My cousin, having been informed that you give all possible support to my affairs,
I wished to write and ask you to continue in the future, considering the extreme
need in which I now find myself after obeying certain commands of the king,
which caused me to enter this war. You will learn more fully from the commander
of Saint John, my ambassador, whom I have instructed to communicate everything
to you. Please give him such assistance as he needs and believe what he tells
you on my behalf. By doing this you will oblige me increasingly to you, as our
Lord knows. Having commended myself to your good grace, I pray that he keep you
in his protection. From Arnhem, this eighteenth day of July [year absent].

This translates the apparent sense; it is not a replacement for the literal
reading above. “Certain” interprets the unexpanded `aulc`; 18 July interprets
`dih[u]itieme`. No recipient's personal name or year is supplied in the cipher.

## Residual uncertainties and limits

- **M, line 4:** the small cross assigned EX/x in `lextreme` is supported by
context. Native-image review shows its bar extending left from the upright, unlike the plain plus/g; the value still rests on one occurrence and remains M.
- **M, line 15:** the u in `dih[u]itieme` is ink-heavy, with its stem visible.
The apparent date is 18 July. No year is present in the recovered date clause.
- **M, insertion 7:** the small e after t overlaps a descender from the line above.
The ten-sign sequence reads `entenderes` and the caret places it after `amplement`.
- **I/M, throughout:** several m/n zigzags are distinguished partly by context;
the early provisional labels conflated them. Their occurrence audit is recorded
in `body_audit.json`, but this does not constitute an independent decipherment.
- The raw forms `sueis`, `uouellu`, `cosidere`, `auir`, `aulc` and the repetition
`en ce / ce faisant` have not been silently repaired. They may reflect spelling,
enciphering slips, abbreviations, or residual glyph errors. Native-resolution re-inspection retains these shapes; it does not establish which of those explanations is responsible.
- The title identifies the recipient as grand master of France. The actual person
and the ambassador's personal name remain unestablished. “Commander of Saint
John” is a title in the letter, not a recovered personal name.
- The separate clear letter at folio 24, dated 3 April 1537, is contextual evidence
only. It is not a matching clear copy and cannot supply this letter's year.

## Reproduction

Run `python targets/egmond/decode_audited.py`. It reads explicit shape labels and the
inferred key, replays both raised insertions at checked token anchors, and writes
`complete_raw_reading.txt`. The original failed probes and earlier drafts remain
available as the research trail; they are not alternate accepted plaintexts.

The corrected body plus insertions measures 726 labelled signs, 27 label names.
These are transcription statistics: A and + are variants, A_blotted is an
uncertain instance, and DD/CE each denote one compound sign. Do not equate the
27 labels with 27 historically distinct cipher characters.

Decryption

complete_raw_reading.txt

moncousinpourcequesueisaduertiquedonnesfaueur
auouspossibleaubiendemesaffairesuousaibien
uouellufairelapresentepouruousprieruoulloir
continuerpourladuenircosiderelextremenecessite
laoupourlepresentmetrouuepourauirobeiaulc
commandemensduroilequelestcausequesuisentreen
cesteguerrecommeplusamplement{entenderes}parlecommandeur
desainctiehanmonambassadeurauquelaidonnecharge
uouscommuniquerletoutiluousplairalui
donnerassistencetellequilluiserabesoing
etlecroireencequiluousdiradeparmoience
cefaisantmeobligeresdeplusenplusauous
cescetnostreseigneurauquelapres
mestrerecommandeauostrebonnegraceprie
uousauoiren{sa}gardedarnhemcedih[u]itiemede
iuillet

Reading

letter-body_reading.md

# Charles of Egmond, Duke of Guelders, to the Grand Maître of France, Arnhem, 18 July [year absent]

## Reading

Mon cousin, pource que sueis adverti que donnes faveur a vous possible au bien de mes affaires, vous ai bien vouellu
faire la presente pour vous prier vouloir continuer pour l'advenir, cosidere l'extreme necessite la ou pour le present me
trouve pour auir obei aulc commandemens du roi, lequel est cause que suis entre en ceste guerre, comme plus amplement
entenderes par le commandeur de sainct Jehan, mon ambassadeur, auquel ai donne charge vous communiquer le tout. Il vous
plaira lui donner assistence telle qu'il lui sera besoing, et le croire en ce qu'il vous dira de par moi; en ce ce
faisant me obligeres de plus en plus a vous, ce scet nostre seigneur, auquel, apres m'estre recommande a vostre bonne
grace, prie vous avoir en sa garde. D'Arnhem, ce dih[u]itieme de juillet.

⟨Le tout v[ost]re bon cousin. CHARLES.⟩ ⟨A mon bon cousin, Monsieur le grant maistre de France.⟩

Translation

letter-body_en.md

<!-- English translation of texts/letter-body_reading.md (Claude Opus 5.5, 23 Oct 2026), revised from the "Meaning in modern English" in READING.md; "certain" for the unexpanded "aulc" and the date 18 July rest on the readings READING.md marks as interpretations. -->

# Charles of Egmond, Duke of Guelders, to the Grand Maître of France, Arnhem, 18 July [year absent]: English translation

My cousin, since I have been informed that you give all the support you can to the good of my affairs, I wished to write
you the present letter to beg you to be pleased to continue in future, considering the extreme necessity in which I now
find myself for having obeyed certain commands of the King, which is the reason I have entered this war, as you will hear
more fully from the commander of Saint John, my ambassador, whom I have charged to communicate everything to you. Be
pleased to give him such assistance as he will need, and to believe him in what he tells you on my behalf; in so doing you
will oblige me more and more to you, as our Lord knows, whom, after commending myself to your good grace, I pray to keep
you in His care. From Arnhem, this eighteenth of July.

⟨Wholly your good cousin. CHARLES.⟩ ⟨To my good cousin, Monsieur the Grand Maître of France.⟩

Ciphered address (three lines) not prose

The ciphered address reads "A mon bon cousin / Monsieur le grant maistre / de France"; no personal name is given.

Transcription

address_complete_tokens.txt

cross_null round_null angle long_zig H short_zig seven H short_zig side_bar H four double_loop_stem loop_descender short_zig long_zig H short_zig double_loop_stem loop_descender nine four double_arch eight nine plus double_arch angle short_zig double_cross_tail long_zig angle loop_descender double_loop_stem double_cross_tail double_arch nine five nine corner double_arch angle short_zig side_bar nine looped_f_null round_null end_cross_null

Decryption

address_reading.txt

amonboncousin
monsieurlegrantmaistre
defrance

Key: audited_key.json

06 Sources

G. Lasry, key to the Duke of Guelders’ cipher, BnF fr. 3015 (2023), on S. Tomokiyo’s cryptiana, GL.htm §2.

BnF, Français 3015 catalogue, item 8, folio 16; component FRBNFEAD000049473_d0e176.
Gallica view 27: letter; view 28: ciphered address. Native body image: 4351 × 6122 pixels.
Views 39–40: separate clear letter, 3 April 1537, used for context only.

Transcriptions, inferred key, failed probes, audit trail and replay script: targets/egmond/ in the repository. Manuscript crops: Bibliothèque nationale de France / Gallica.