Boleslaus was an elder son of Duke
Boleslaus I the Cruel and brother of the three other children of his father who survived to adulthood:
Strachkvas,
Doubravka (the wife of Duke
Mieszko I of Poland) and the abbess
Mlada. His mother may have been
Biagota, a mysterious figure known only from her coins. According to some historians, she was the wife of Boleslaus I.
Alliances Boleslaus II took over the rule of the
Duchy of Bohemia as
kníže (a title that may be translated either as duke or prince) on his father's death in 972. Like his father, Boleslaus II initially quarrelled with the
Ottonian kings of
Germany. In 974, he and Duke
Mieszko I of Poland supported the rebellious Duke
Henry II of Bavaria in his civil war against the rule of Emperor
Otto II. In 976, Henry was defeated and fled to Boleslaus' court at
Prague Castle, after which Otto's forces campaigned in the Bohemian lands. Finally in 978, Boleslaus solemnly pledged allegiance to the emperor at the Easter festivities in
Quedlinburg. In turn, relations with
Poland deteriorated from about 980 onwards. When Emperor Otto II died in 983 and was succeeded by his minor son
Otto III, the Bohemian alliance with Poland was discarded, as Boleslaus again allied with the insurgent Bavarian Duke Henry, while Mieszko I took the side of the young king. Moreover, when Boleslaus occupied the Saxon
Margravate of Meissen, he thwarted the plans of Mieszko's son
Bolesław, who had married a daughter of Margrave
Ricdag. In 987, Boleslaus had to retire from Meissen, and from about 990, he sparked a long-lasting conflict with Poland around the lands of
Silesia and
Lesser Poland (the
Polish-Bohemian War). In 992, he approached King Otto III and participated in an unsuccessful campaign against the
Lutici tribes in the wake of the
Great Slav Rising of 983.
Unification of the Bohemian lands Boleslaus's reign is most notable for the foundation of the
Diocese of Prague in 973, which earned him the epithet "The Pious" by the medieval chronicler
Cosmas of Prague. Nevertheless, the Bohemian diocese was placed at that time within the jurisdiction of the
Archbishop of Mainz, and Emperor Otto II enforced the appointment of the
Saxon monk
Thietmar (
Dětmar) as first bishop. Meanwhile, the struggle with the rival
Slavník dynasty flared up again from 981 onwards, when Prince
Soběslav of the Slavník dynasty began to forge alliances with the Polish and
Saxons. Upon Bishop Dětmar's death in 982, Soběslav's brother
Adalbert (later known as Saint Adalbert of Prague) was appointed his successor until he abandoned his primacy to lead a mission to the
Old Prussians in 994. On 28 September 995, Boleslaus' forces and the confederate
Vršovci clan stormed
Libice Castle in southern Bohemia and massacred the members of the Slavník dynasty that were found there. Boleslaus's brutal triumph ensured the unity of Bohemia under a single ruler. == Marriages and issue ==