The Peace of Bautzen (; ; ) was a treaty concluded on 30 January 1018, between Holy Roman Emperor Henry II and Bolesław I of Poland which ended a series of Polish-German wars over the control of Lusatia and Upper Lusatia (Milzenerland or Milsko, the eastern part of the margraviate of Meissen (Miśnia)) as well as Bohemia, Moravia and Slovakia.
Bolesław had enjoyed the close friendship of the emperor Otto III and after his death supported one of Otto's followers, Eckard I, Margrave of Meissen for the position of Holy Roman Emperor, against the claims of Henry II. After both emperor Otto III and Eckard's death in 1002, Bolesław conquered Eckard's domain of Meissen, as well as the march of Lusatia. Once Henry secured his position within Germany, an agreement was reached which left Bolesław with Lusatia and Upper Lusatia while the Polish duke in turn recognized Henry as Holy Roman Emperor.
Fighting soon resumed, however, after an unsuccessful assassination attempt against Bolesław—which he believed had been ordered by Henry, who denied the charge—occurred soon after the peace was concluded. Bolesław took control of Bohemia, having previously acquired Moravia and Slovakia. In the ensuing struggle Bolesław allied himself with the Holy Roman Empire's noble opposition to Henry, while the emperor sought support among the Lutici, a Slavic pagan Polabian tribe. An intermediate peace was concluded in Merseburg in 1013 which preserved the territorial status quo, with Bolesław holding on to Moravia and Slovakia, while Jaromir was made the ruler of Bohemia (though he was soon deposed by his brother Oldrich). Bolesław however agreed to support the Emperor's Italian campaign. Open warfare continued when Bolesław I did not comply with this condition, and instead supported Henry II's Italian adversaries. Henry II was however unable to defeat Bolesław I, and agreed on a peace in Bautzen (1018) which left the Duke of Poland in charge of the Lusatian march and Upper Lusatia. The two rulers also strengthened the dynastic bonds between them through Bolesław's marriage with Oda, first daughter of Margrave Eckard. The emperor also promised to aid Bolesław in his intervention in the Kievan succession crisis in the summer of 1018 with contingents of German and Hungarian troops which enabled the Polish ruler to capture Kiev and reclaim the previously lost Cherven Cities.
Prelude
Merseburg (1002)
After the death of emperor Otto III, Bavarian duke Henry IV and Meissen margrave Eckard (Ekkehard) I competed for succession. When Eckard I was murdered on 30 April 1002 in Pöhlde, Polish duke Bolesław I, who had supported Eckard's candidature, probably with approval from Eckard's family. He took control of both Bautzen and Meissen, after the inhabitants themselves had forced the German troops to leave the city, while other German knights voluntarily recognized Bolesław's rule in the region.
On 25 July 1002 at a Hoftag (imperial meeting) held in Merseburg, Henry II did neither protect him, nor punish the assailants. and denied Henry II the oath of allegiance for the duchy. and was determined to contest the Polish claims to the Bohemian duchy. A few months later, together with Veleti and Czech allies, Henry II mounted another campaign.
The treaty was confirmed by the marriage of Richeza, a niece of Otto III, to Mieszko II, a son of Bolesław I. and refused to recognize that Lusatia and Upper Lusatia were his only as fiefs. Instead, he supported Crescentian antipope Gregory VI and intrigued against Henry II in Italy, who had denied Gregory his support in Pöhlde. As a result of these setbacks Henry II withdrew. The inhabitants of the city also erected a cross on the wall which faced the pagan Lutician allies of the emperor.
The contemporary German chronicler Thietmar, who was generally ill-disposed towards Poles, commented on the peace with the words "non ut decuit sed sicut fieri potuit", meaning "not as it should have been but as was possible in the circumstances".
Both parties also exchanged hostages.