A Czech duke of the Premyslid dynasty; he probably ruled from the year 972. Immediately after the commencement of his rule (973) a bishopric was established in Prague Castle and with it the first monastery in Bohemia; the church of St. George was expanded during his reign to a three-aisled basilica, the first of its kind in Bohemia. In 993 he announced the Boleslaus Privileges, one of the first attempts at legislation in the Czech lands. In 995, he took advantage of the fact that the army of the competing family, the Slavniks, had left the castle and settlements and had all the members of the dynasty murdered, including the children, then going on to destroy all their remaining castles and settlements. The reign of the Přemyslid dynasty was thereby reaffirmed.