Stories / Pomerania · Saxony · Vienna · 1715–1717

Story · Great Northern War, 18th century

Stralsund, 1715 – Vienna, 1717: Wackerbarth’s ciphered letters

In November 1715, before besieged Stralsund, Count Wackerbarth, in command of the Saxon troops, writes to his wife in Vienna a long letter almost entirely in cipher: what she should answer, at the imperial court, to those who plead for the King of Sweden. Nineteen months later, in Vienna, he reports to Augustus II an overture from the Emperor’s chancellor. We recovered the key of these ciphers from the decipherments of the time in the same holdings, put it to the test, and publish what it allows us to read.

Story by Brice Dudout · reading with Claude · prior and simultaneous work: Anne-Simone Rous · documents: Sächsisches Hauptstaatsarchiv Dresden, 10026 Geheimes Kabinett, Loc. 00712/05 and Loc. 00713/01 · published 11 November 2026

The letters and their writers

August Christoph von Wackerbarth (1662–1734), general and cabinet minister of Augustus II, Elector of Saxony and King of Poland, led several embassies to Vienna; in 1715 he commanded the Saxon corps at the siege of Stralsund.[3][4] His wife, born Caterina di Balbiano (Catharina Balbiani), widow first of a Count of Salmour and then of Margrave Charles Philip of Brandenburg-Schwedt, was close to Prince Eugene.[3] Rouven Pons devoted a study to her, “Catharina Gräfin von Wackerbarth (1670–1719) als kursächsische Gesandte in Wien” (2006), cited by Anne-Simone Rous, which we have not consulted: its title alone says that she acted in Vienna as an unofficial Saxon diplomat.[5]

Volume Loc. 00712/05, filed with the correspondence of Flemming and Wackerbarth, holds three consecutive pieces that answer one another:

• f. 306: a playful “full power”, signed “Le Comte de Wackerbart”, “made at the camp before Stralsund”, authorising “our intimate and best friend, Mr the General Field Marshal Flemming” to treat with the King of Poland… over a Spanish horse;
• ff. 307–314: the “Reply to the letter from 306”, “at the camp before Stralsund, the 20th 9bre 1715” (306 is, in the cipher, the code name for Vienna);
• ff. 315–317: the “Extract of a letter from 306.66.857 […] dated the 5th of 9bre 1715”, in cipher, with an interlinear decipherment of the time; a contemporary hand wrote above it “La Comtesse de Wa…” and “au C. de Wa…”.

The “Reply” opens: “I have seen by yours of the 5th of this month, which you were kind enough to write me, […] an argument that was put to you”; the extract of the 5th reports precisely the “long argument” of a speaker at the imperial court. Near the end the cipher says: “Voilà, ma chère femme” (there, my dear wife), “something with which to answer those who talk to you”. The writer is besieging the town, has “our cannon and our mortars” brought to the batteries and speaks of summoning General Dücker, the Swedish governor. Hence our attribution: Wackerbarth, in camp, to the Countess Wackerbarth, in Vienna; a probable and strong attribution that does not rest on the decipherment alone. The piece is a fair copy, unsigned, annotated in the margin by another reader: most likely a copy passed on to Flemming or to the Cabinet (hypothesis).

Two corrections. Our working inventory, made from thumbnails, gave “Flemming → Wackerbarth”: the reverse of what the Countess’s extract and the cipher itself show. It also read “8bre” (October). The month is written with a long-tailed 9, the same shape as the 9s in the cipher of the extract: it should be read 9bre, November. The chronology of the siege confirms it: the letter speaks of the entrenchment taken before Stralsund and of the capture of Rügen, which date from 4–5 and 15–16 November 1715.[2]

Stralsund, November 1715: the end of a siege seen from the Saxon camp

Charles XII, back from Turkey, had shut himself up in Stralsund in November 1714. Prussians, Danes and Saxons besieged the town from July to December 1715; Usedom fell in August, the Swedish entrenchment before the town was turned on the night of 4–5 November in an attack led by Wackerbarth, and the allies landed on Rügen on 15 November; Charles XII left the town by sea on 19 December, and the garrison capitulated a few days later. Wismar held out until April 1716.[2] The letter of 20 November was written between these moments.

It gives a precise and unboastful picture. In Germany the King of Sweden has only Stralsund and Wismar left; the attack is pressed “to such a point” that, short of waiting for “the last extremity, a general assault”, he will gain nothing but “the satisfaction of having remained its master a few days longer”. Wismar, since the island of Poel was taken, is pressed by land and sea and cannot avoid falling this winter. What is left of the Swedish troops, beaten on Usedom, in the entrenchment and on Rügen, is shut up with the King in Stralsund, “enclosed” by land and sealed by sea by Danish prams and frigates. The writer is “so close to the salient angle of the counterscarp” that he expects to master the place in a few days.

Augustus II’s peace: general, never separate

The heart of the letter is political. In Vienna a “reasoner” had argued to the Countess that the northern allies had an interest in sparing the King of Sweden, that Saxony would have everything to fear from him in Poland, and that his firmness was to be dreaded. Wackerbarth answers point by point:

• King Augustus is “much inclined to peace, but to a general peace, in no way a separate one”, such as the conjuncture can call for and one that secures tranquillity;
• he has “no” intention “of lending a hand to a total ruin of the Crown of Sweden”, and has even stipulated so in his treaties with his allies, provided the peace does not lay the foundation of a new war;
• if the King of Sweden suffers, it is the fruit of “his own will”: neither the allies’ disposition, nor the Emperor’s exhortations, nor the exhaustion of his people, nor the Turk’s too distant help have made him yield.

He compares this argument with the letter that the Comte de Croissy, France’s envoy to Charles XII, had written at the start of the campaign to dissuade the allies from attacking Stralsund and Rügen: all it produced, he says, was “a closer union among the allies”.

The fear of a return to Poland

The “reasoner” had raised a threat: Charles XII could gather his “remnants”, return to Poland and put himself “at the head of our rebels”, two-thirds of whom would be for him. Wackerbarth turns the argument round: all the more reason to destroy those remnants now, while they are shut up in Stralsund with the King himself. The fear was real at the end of 1715: the Polish nobility was then openly opposing the Saxon troops stationed in the kingdom, and a confederation against them was formed at Tarnogród in the last weeks of the year (general context, not checked here against a study).

The Emperor’s mediation

The letter ends with an overture. As soon as his guns are in battery, Wackerbarth will write to General Dücker to “touch the heart of his King”; and he is writing that very day to Count Virmond, “minister of the Emperor”, to ask him to come to him, so that the peace, if the King of Sweden lets himself be moved, may be made “under the direction and by the mediation of the Emperor”: the imperial court “will be grateful for it”. Damian Hugo von Virmont was then Charles VI’s envoy at the court of the King of Sweden, in Stralsund itself.[6] The letter thus shows a two-way channel: the official offer of imperial mediation made from the camp, and its unofficial preparation in Vienna by the Countess, who is to bring the subject back “on the table… without affectation”.

Vienna, June 1717: Sinzendorf’s overture

Volume Loc. 00713/01 holds Wackerbarth’s correspondence during his mission to Vienna in 1717. Relation XXII, a copy of a dispatch to the King (“Sire”) dated 14–16 June 1717, mixes clear text and cipher. We read it in part (89.5% of the ciphered words), and what follows is only a cautious paraphrase.

The imperial court, Wackerbarth writes, had been playing for time until the outcome of the Hungarian campaign against the Turks. But the court chancellor, Count Philipp Ludwig von Sinzendorf, called him in to tell him, “by order of the Emperor”, that after mature deliberation the Emperor wished to restore the tranquillity of the Empire and “the entire peace of the North” on solid foundations and “a just balance”, and was ready to enter with the King of Poland and the King of England “into a concert” on what was to be done, both in negotiation and in execution. The same overture had been made the day before to Saint-Saphorin, George I’s representative in Vienna. The presence of the Russians in the Empire would be referred to the Diet of Ratisbon and the directors of the Circles. Saint-Saphorin thought it could go as far as “a triple alliance between the Emperor, the King of England and the King”; the King of England, Wackerbarth adds, would take the same measures “with regard to Poland” and would not give back to the King of Sweden “an inch of land” of his lost German provinces. Secrecy is extreme: not even a referendary was admitted to the conference.

Hypothesis. This overture seems to foreshadow the Treaty of Vienna of 5 January 1719, a defensive alliance between Charles VI, George I as Elector of Hanover and Augustus II as Elector of Saxony, aimed at the presence of Russian troops in Poland and the Empire.[7] L. R. Lewitter, its historian, places Augustus II’s decision at the end of August 1717 (full power given to Flemming on 6 August) and notes that Charles VI then refused any new engagement before the end of the Turkish war.[7] The report of June 1717 nuances that picture: even before Belgrade, Vienna was quietly sounding out Saxony and Hanover. A direct link between this overture and the treaty remains to be established from the sources.

The same volume holds a letter of 24 April 1717 to Flemming (ff. 29–32), worried about the King of Sweden’s “views” on Poland and a landing towards Danzig. Anne-Simone Rous lists it (under the date “24th July”) as not deciphered.[1] A sheet of the time (f. 33) nevertheless renders its whole cipher: our key, built without it, agrees with it. This is a check, not a discovery.

The cipher

Both letters use the same system, which we call S1 (47 of the 50 values they share are identical in 1715 and 1717).

• Homophones. Each French letter has several numbers of one or two digits: e = 2, 10 or 35; s = 29, 51, 57 or 77; u = 5, 6 or 54; r = 26, 27 or 60; t = 28 or 52.
• Letter groups. Some numbers stand for two letters: 63 = ff, 65 = tt, 76 and 85 = st, 72 and 90 = ch, 97 = la, 96 = le.
• A three-digit nomenclator for names and titles: 150 the King, 164 Prince Eugene, 168 the Emperor, 177 the Tsar, 187 the King of Sweden, 198 Stanislas, 217 the King of England, 284 count, 292 Poland, 306 Vienna, 314 Danzig.
• Mixed clear text. Harmless passages stay in clear; the cipher often starts mid-sentence. In 1717 four-digit numbers serve as nulls.

It is an ordinary chancery cipher, sound against a hurried reader, weak against a patient one: short words, unevenly spread homophones and neighbouring clear text give it away. In the autumn of 1717 the correspondence moves to another cipher, already known to us from a key of Flemming’s.

How we read it

1. The key learned from the glosses of the time. For 1715, the Countess’s extract (ff. 315–317) carries a secretary’s decipherment above the numbers: every number–letter pair was recorded, and the key fixed by majority vote (57 numbers, 934 pairs), then frozen and hashed. For 1717, the same work on the glossed pages of the volume.
2. A single measurement, fixed in advance, with controls. A portion of the letter of 20 November (f. 310v, 307 groups), designated before any transcription, was transcribed blind by an AI agent. Decoded once, it scores 0.945 on a lexical measure, against at most 0.730 for 400 control keys (permuted or shuffled), with the threshold set at 0.77: key validated. For 1717 the validation is mixed: two first tests failed, a third (z = 11.5 on a fresh portion) passed; the decision to read Relation XXII on that test alone was taken after the measurement, and we declare it.
3. Reading by sense, word by word, with a class for each word: certain, probable, restored, unresolved.
4. Brice Dudout’s blind review. A sheet of nine doubtful signs and two control questions, with no reading visible, asked him to choose the shape he saw. Both controls were passed; three words moved from probable or restored to certain. The integration rules had been hashed beforehand.

What remains uncertain

• 1715: read. Under Daniel Bourdeau’s rule (95% of the ciphered words read by sense, restored words not counting), the letter of 20 November is read at 96.75%: 774 certain, 118 probable, 12 restored and 18 unresolved words out of 922. Probable words often rest on values taken from 1717 (72 = ch, for instance) or deduced here (96 = le). The classing of words is that of a single reader, an AI agent; the blind review covered nine signs only.
• 1717: read in part. Relation XXII reaches only 89.5% (575 certain, 66 probable, 66 restored, 9 unresolved out of 716), and its validation is weak. A variant counting recurring homophones would reach 97.9%; it is not adopted.
• The clear text. On the record, the clear text of the 1715 letter is sometimes abridged (“…”): only the ciphered passages are transcribed and counted in full.
• Attribution and support. Wackerbarth is named in clear nowhere in ff. 307–314; the attribution rests on the Countess’s extract, on “ma chère femme” and on the siege context. The recipient of the copy kept in Dresden remains a hypothesis.
• Context. The military and diplomatic facts were checked on 11 November 2026 against reference works and online encyclopaedias, not against the specialist studies (Voges 1922 on the siege, Pons 2006 on the Countess, Lewitter 1970 read in part); the links with the 1719 treaty and with the Tarnogród confederation are hypotheses.
• No images. The Dresden scans are “In Copyright”: we reproduce no image or detail. They can be consulted on the Saxon archives’ website.

References

1. Prior and simultaneous work

   Anne-Simone Rous, “The Keys of Diplomacy. The encrypted correspondence of Saxon-Polish Ministers Wackerbarth and Flemming 1700–1720”, University of Tartu repository. dspace.ut.ee ↗

2. Siege

   “Belagerung von Stralsund (1715)”, Wikipedia (de), consulted 11 November 2026 (chronology, Wackerbarth’s role in the attack of 4–5 November); the reference study, H. Voges, Die Belagerung von Stralsund im Jahre 1715 (1922), was not consulted. Wikipedia ↗

3. Biography

   “August Christoph von Wackerbarth”, Wikipedia (de), consulted 11 November 2026. Wikipedia ↗

4. Archives

   Dresden, Sächsisches Hauptstaatsarchiv, 10026 Geheimes Kabinett, Loc. 00712/05 (1714–1715), ff. 306–317, and Loc. 00713/01 (1717), ff. 29–33 and 71–80v; records and scans (In Copyright): Loc. 00712/05 ↗, Loc. 00713/01 ↗.

5. Not consulted

   Rouven Pons, “‘Die Dame ist romanesque und coquet…’. Catharina Gräfin von Wackerbarth (1670–1719) als kursächsische Gesandte in Wien”, Mitteilungen des Instituts für Österreichische Geschichtsforschung 114 (2006), pp. 65–95 (cited from A.-S. Rous’s bibliography).

6. Mediation

   “Damian Hugo von Virmont”, Wikipedia (de), consulted 11 November 2026 (envoy to the court of the King of Sweden at Stralsund in 1715). Wikipedia ↗

7. Treaty of 1719

   L. R. Lewitter, “Poland, Russia and the Treaty of Vienna of 5 January 1719”, The Historical Journal 13/1 (1970), pp. 3–30; chapter consulted online. Cambridge ↗ · SGECR ↗

8. Framework and repository

   Daniel Bourdeau, cyphersolver repository: the 95% rule; Relation XXII is proposed there as a partial reading: PR #418 ↗.

9. Reading

   Record “Wackerbarth to his wife, camp before Stralsund, 20 November 1715” on the Documents page, with the probable text, the counts and the credits.