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 the Polabian Slavs. On the other hand, the supporters of the Gero's invasion theory believe that the Margrave did actually carry out a successful invasion, as a result of which Mieszko I was forced to pay tribute to the Emperor and also was compelled to adopt Catholicism through the German Church. The thesis that proposes the introduction of Catholicism as a result of this war finds no confirmation in German sources. The homage is then a separate issue, since, according to the chronicle of Thietmar, Mieszko actually paid tribute to the Emperor from the lands "usque in Vurta fluvium" (up