page_title: Boleslaus I, Duke of Bohemia
section_title: Reign
hierarchical_section_title: Boleslaus I, Duke of Bohemia / Reign
caption_attribution_description: Čeština: Mapa rozsahu českého státu v 10. století za vlády Boleslava I. a Boleslava II. English: Map showing Czech state in the 10th century under Boleslav I. and Boleslav II.
context_page_description: Boleslaus I the Cruel, also called Boleslav I, a member of the Přemyslid dynasty, was ruler of the Duchy of Bohemia from 935 to his death. He is notorious for the murder of his elder brother Wenceslaus, through which he became duke. Despite his complicity in this fratricide, Boleslaus is generally respected by Czech historians as an energetic ruler who significantly strengthened the Bohemian state and expanded its territory. His accomplishments include significant economic development due to an expansion in trade, the introduction of silver mining and the minting of the first local coinage, the Prague denarius.
context_section_description: Once having taking over the Prague throne, one of Boleslaus's major concerns was the tribute paid yearly to the East Frankish kings as stipulated in the peace treaty that Henry the Fowler had established with Boleslaus's brother Wenceslaus. He stopped the payment shortly after he ascended the throne, which led to a prolonged war with Henry's successor King Otto. In 935 Boleslaus attacked the Thuringian allies of the Saxons in the northwest and defeated two of Otto's armies (from Thuringia and Merseburg). The war then deteriorated to border raids (the general pattern of warfare in this region at the time) and reached its conclusion in 950, when King Otto besieged a castle owned by Boleslaus's son. This prompted Boleslaus to sign a peace treaty with Otto. Although he remained undefeated, he promised to resume the payment of tribute.
  Five years later, the armies of Czechs and Germans allied against the Magyars in the victorious Battle of Lechfeld on 10 August 955. After the battle, the remainder of the huge Magyar army turned to Bohemia, where it was crushed by Boleslaus. Shortly afterwards, in October, he also helped Otto to crush an uprising of Slavic tribes led by the Obotrite princes Nakon and Stojgněv on the Lower Elbe river in the Battle on the Raxa.
  The defeat of invading Hungarians brought the same benefits to both Germans and Czechs. Less obvious is what Boleslaus expected to gain from his participation in Otto's war against the Obotrite princes in far north. He probably wanted to ensure that his powerful German neighbors did not interfere with him in expanding the Bohemian territories to the east.
  As a result of the victory, Boleslaus freed the Moravian lands from Magyar raids and expanded his territory, which in turn was later conquered by Polish dukes and became known as Upper Silesia and Lesser Poland. By occupying the city of Kraków, he controlled important trade routes from Prague to Kiev and Lviv. To defuse the Bohemian-Polish conflict, Duke Boleslav married his daughter Dobrawa to the pagan Piast prince Mieszko I in 963/964, and helped bring Christianity to Poland. He even allied with Mieszko in the campaign against the Saxon count Wichmann the Younger.
  According to the medieval chronicler Cosmas of Prague, Duke Boleslaus died on 15 July 967, a date questioned by recent research. He was succeeded by his eldest son Boleslaus the Pious.
caption: Expansion of the Bohemian state during the reign of Boleslav I and Boleslav II
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