The first historical ruler of Poland, Mieszko I is considered the de facto creator of the Polish state. He continued the policy of both his father and grandfather, who were rulers of the pagan tribes located in the area of present Greater Poland. Either through alliances or by use of military force, Mieszko extended the ongoing conquests and early in his reign subordinated Kuyavia and probably Gdańsk Pomerania and Masovia. For most of his reign, Mieszko I was involved in warfare for the control of Western Pomerania, eventually conquering it up to the vicinity of the lower Odra River. During the last years of his life he fought the Bohemian state, winning Silesia and probably Lesser Poland.
Mieszko I's marriage in 965 to the 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 expanding and improving the so-called war monarchy system.
According to existing sources, Mieszko I was a wise politician, a talented military leader and charismatic ruler. He successfully used diplomacy, concluding an alliance with Bohemia first, and then with Sweden and the Holy Roman Empire. In foreign policy, he placed the interests of his country foremost, even entering into agreements with former enemies. On his death, he left to his sons a country of greatly expanded territory, with a well-established position in Europe.
Mieszko I also appeared as "Dagome" in a papal document from about 1085, called Dagome iudex, which mentions a gift or dedication of Mieszko's land to the Pope (the act took place almost a hundred years earlier).