Boleslav I (bō'lusläf") [key], d. 967, duke of Bohemia (929–67). He became duke by assassinating his elder brother, Duke Wenceslaus (see Wenceslaus, Saint). Although Boleslav was involved in constant warfare against the encroaching Germans, he was able to create a Bohemian state. He built fortresses to control restless tribes, conquered Moravia and part of Silesia, and encouraged the spread of Christianity. In 950 he was forced to recognize German suzerainty, although Bohemia remained largely autonomous.
