Mieszko I of Poland Pomerania, eventually conquering it up to the vicinity of the lower Oder river. During the last years of his life, he fought the Bohemian state, winning Silesia and probably Lesser Poland. Mieszko I's alliance with the Czech prince, Boleslaus I the Cruel, strengthened by his marriage in 965 to the Czech Přemyslid princess Dobrawa, and his baptism in 966 put him and his country in the cultural sphere of Western Christianity. Apart from the great conquests accomplished during his reign (which proved to be fundamental for the future of Poland) Mieszko I was renowned for his internal reforms, aimed at
Mieszko I of Poland Mieszko allied his country with Sweden against Denmark. The alliance was sealed with the marriage of Mieszko's daughter Świętosława with the Swedish king Erik. The content of the treaty is known from the not entirely reliable, but originating directly from the Danish court tradition account given by Adam of Bremen. In this text, probably as a result of confusion, he gives instead of Mieszko's name the name of his son Bolesław: Mieszko decided on the alliance with Sweden probably in order to help protect his possessions in Pomerania from the Danish King Harald Bluetooth and his son Sweyn. They may