Duke Ernst of Bavaria to Wilhelm V: the “Post Scripta” dot cipher of 1583

Until 15 October 2026 this record was filed on one page with thirteen other ciphertexts of the same key volume. They are different ciphers, each with its own page; the largest group is System A′ of the dukes’ agents in Hungary, and the other piece of 1583 is a letter to Duke Wilhelm V.

01 The sheets

Seventeen DECODE images show sheets ruled in red into squares, 66 by 43, with dots, a few crosses and other marks; “Postscripta” heads f. 96R, “Aliud Postscript” f. 101V, and the outer leaves are docketed “Presentatur 12 May … 83 Monaci” (f. 107V) and “Presentatur 19 May 83” (f. 115V). On 21 September 2026 we described them as grilles to be laid over clear cover letters on ff. 115–118, which DECODE had not photographed, and closed the record as blocked. That was wrong.

02 Leighton’s decipherment

A. C. Leighton described the same sheets in 1974 under the volume’s old shelfmark, Kasten schwarz 13478, ff. 96–115; his plates of f. 96R match the DECODE image. The dots fall into columns, at least three to a row, which pointed him to a strip key with several alphabets. In the same volume (f. 49) he found four parchment strips: one pair with three alphabets in normal order, the other with three mixed 24-letter alphabets and, between the letters, a list of names and words (Imperator, Pontifex, Colonia, Capitulum…; German on the mixed pair: Kayser, Capitel, Brueder, Salentin). Laid on f. 96R, the mixed strip gave the opening at once, ANFANG / SDEN, and a dot between two letters gave a code word (between I and O, “Kayser”). A dotted stroke doubles a letter, a closing sign marks the end of a section, and a looped sign stands for E. L. (Euer Liebden).

Leighton prints the whole text in its original spelling, divided into words, with code-list words in brackets (pp. 836–838), and leaves a few of the encipherer’s slips as written. He checked it against two chancery decipherments he found in the same archive: ff. 96R–101R in Kasten schwarz 3634 ff. 285–287a, headed “Extrait aus H. Ernst Ziffer 22 April 83”, and ff. 104R–107R in Kasten schwarz 3636 f. 42. f. 103V holds a faulty first attempt at the opening. With the same key he also deciphered a further undated dot letter, Kasten schwarz 3636 ff. 43R–45½R, on Count Arnold of Manderscheid’s vote.

The sender is Ernst of Bavaria, elected archbishop of Cologne on 23 May 1583 after Gebhard Truchsess was deprived for turning Protestant; the recipient is his brother Wilhelm V. The first postscript is dated “Datum (Cöln) den zwenundzwainzigisten tag april”.

03 The texts

Leighton’s article (1974) is in copyright, so his text is not copied here. It is free to read on the Bavarian State Library’s scan of the journal: pp. 836–838.

• ff. 96R–101R, Cologne, 22 April 1583: the imperial commissioners’ truce talks with the cathedral chapter, Archduke Ferdinand and the legate, Salentin of Isenburg, Württemberg, the Baden marriage, and the canonries of the Bishop of Metz.
• ff. 101V–102R, another postscript: the chapter’s letter to the Catholic estates, and a new election day for 15 May.
• ff. 104R–107R, received 12 May: the bishop of Vercelli’s arrival, a Calvinist tumult in the city, a ride to Düsseldorf and the Jülich marriage talks, Count Adolf of Neuenahr, the summons sent to Philipp Truchsess.
• ff. 108R–115V, received 19 May: French intrigues, the papal deprivation and the election day, the chapter’s troops and money (ten thousand crowns from the Pope, hopes of Spanish help), and Parma as a possible commander.

04 What remains

• No transcription of the dots was made here, so Leighton’s reading is cited, not checked dot by dot. f. 115 is not among the DECODE images.
• The writing seen through f. 102 (“Die 4 od 5000 Cronen…”), which we took for a cover letter, is not explained by Leighton.

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.

ff.96R-101R, Postscripta, Cologne 22 April 1583

Ernst to Wilhelm V: the imperial commissioners' truce talks with the cathedral chapter, Archduke Ferdinand and the legate, Salentin of Isenburg ('ain aufrech bayrisch herz'), Württemberg, the Baden marriage and the Bishop of Metz's canonries; dated Cologne 22 April [15]83.

Decryption: bsb00009436?page=160

ff.101V-102R, Aliud Postscriptum

The chapter's letter to the Catholic estates of the Empire, and a new election day to be set for 15 May.

Decryption: bsb00009436?page=160

f.103V, trial not prose

A faulty first attempt at the opening of f.96R (Leighton: E/F and K/R confused, Kaiser spelled out).

Decryption: bsb00009436?page=161

ff.104R-107R, presented at Munich 12 May 1583

The bishop of Vercelli's arrival, a Calvinist tumult in the city, Ernst's ride to Düsseldorf and the Jülich-Cleves marriage talks, Count Adolf of Neuenahr, and the convocation sent to Philipp Truchsess.

Decryption: bsb00009436?page=161

ff.108R-115V, Postscripta, presented at Munich 19 May 1583

French practices, the papal deprivation and the election day, the chapter's troops and money (ten thousand crowns from the Pope, hope of Spanish help), Parma as possible commander, and Duke Ferdinand.

Decryption: bsb00009436?page=161

05 Sources

• Bayerisches Hauptstaatsarchiv, Kurbayern Äußeres Archiv 4591 ff. 96–114, via DECODE R9319; key strips f. 49, DECODE R9304 (login; publication of the images needs the archive’s permission, so this page shows none).
• Albert C. Leighton, “Eine neuentdeckte Chiffre und die erzbischöfliche Wahl zu Köln – 1583”, Zeitschrift für bayerische Landesgeschichte 37 (1974), pp. 828–844, BSB scan bsb00009436.
• Pointer: ry-xu, GitHub issue #88 (22 October 2026).

Notes: targets/r9319/.