[citation needed] Bolesław maintained good relations with Emperor Otto III (r. 983/996–1002): together they fought against the West Slavic Lutici tribes and the Obotrites.

[6] The circumstances changed significantly, when in January 1002 Emperor Otto III suddenly died at the age of 21, leaving no heirs nor any succession arrangements.

[7] Henry then launched an indecisive campaign against Herman of Swabia, but was recognised by the Thuringians, Saxons and lower Lotharingians in subsequent months, either by homage or renewed election.

Moreover, an attempt was made on Bolesław's life, which he escaped only with the help of Duke Bernard of Saxony, the Nordgau margrave Henry of Schweinfurt and several friendly German nobles.

[citation needed] Thietmar of Merseburg reported in his Chronicon that Bolesław set Strehla Castle in the Margraviate of Meissen ablaze on his way back to Poland, although it remains unclear why he did so.

[11] At the time, the castle town of Strehla (Polish: Strzała) was in the possession of Regelinda, the new wife of Herman I, Margrave of Meissen, the oldest son of Eckard.

[citation needed] King Henry in turn renewed his Bavarian fellowship with the Přemyslid rulers of Bohemia, old-time enemies of the Polish Piast dynasty.

[15] But then the Polish duke Bolesław I the Brave intervened by militarily invading and occupying Bohemia, and putting Boleslaus III (who had been in his custody) back in power as his vassal.

[16] During Easter 1003 in Quedlinburg, Henry II forged an alliance with the Luitici tribes against Bolesław to drive him out of the Saxon eastern marches and out of Poland.

In return, Bolesław swore an oath of allegiance, promised to support Henry's bid for the crown of Holy Roman Emperor and aid him in his Italian campaigns.

To confirm the alliance, Bolesław's son Mieszko II Lambert married the German noblewoman Richeza of Lotharingia, a distant relative of King Henry.

[citation needed] After Merseburg, Bolesław got entangled in the Kievan succession crisis backing his son-in-law Sviatopolk I against Henry's candidate Yaroslav the Wise.

The war spread over to Bohemia, where Mieszko's forces ravaged the lands and, while Bolesław again lost control over Kiev, peace efforts were resumed by the Saxon nobility.