Mieszko I
Mieszko I (c. 935-May 25 992). First (historically known) Piast duke of Poland. Son of semi-legendary Siemomysl. In 964 or, more probably, in 965 he married Dubrawka (or Dobravy), a daughter of Boleslav I, duke of the Bohemians. 978 - married Oda, daughter of Dietrich (Theoderic) v.Haldesleben, warden of the Saxon North March (965-985), kidnapped from monastery of Kalbe.
The early career of Mieszko was dominated by fighting with the Baltic-bordering tribes of Wieletes and Volinians and their ally, the Saxon landgraf Wichman. Mieszko was baptised in 966, probably under the influence of his Christian first wife and in order to avoid confrontation with the Holy Roman Empire to the west; he built a church dedicated to Saint George at Gniezno. He had probably one sister of unknown name, and two brothers, one of them, unknown from name, was killed in battle with Wichman in 963-965, and second, named Czcibor, died in Battle of Cedynia in 972.
His reign is likely to have begun circa 960 in Greater Poland, Cujavia, Masovia and eastern Pomerania. In 960s he probably at least partially conquered western Pomerania, and in 990 he conquered Silesia and Little Poland. Much of his military activity was along the Baltic coast, in Pomerania. He defeated the Margrave of the Northen March at Cedynia in 972, and reached the mouth of the Oder river in 976. Responding to Mieszko's advances, the Margrave appealed to Holy Roman Emperor Otto II for help. The decisive battle, fought in 979, ensured Mieszko's position as sole lord of Pomerania. To celebrate his victory, he dedicated a city, Gdansk, at the mouth of the Vistula River, to compete with the ports of Szczecin and Wolin on the Oder.
In 981 he lost so called Grody Czerwienskie to the Kiev prince, Volodymyr the Great. In 986 he pledged allegiance to Otto III, and helped him with wars with Polabians. Short before his death he gave his state to Pope in a document usually called Dagome Index.
From first marriage he had a son Boleslaw I Chrobry and a daughter Światosława, better known as Sigrid the Proud. From second marriage he had three sons, Mieszko, Lambert, and Swiatopelk
see also History of Poland