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 situation at that time. Another debatable point is Thietmar's claim that Mieszko "subordinated himself to the King". Most historians believe that it was only a matter of recognition of Otto's royal authority. Some suggest that a fealty relationship could in fact be involved. Whether or not the German-Polish invasion of Bohemia actually happened, the friendly relations between the Czechs and the Poles came to an end. Bohemia resumed its earlier alliance with the Lutici, which caused in 990 a war with Mieszko, who was supported by Empress Theophanu. Duke Boleslav II was probably the first one to attack. As a