Casimir I(kăs`əmēr), c.1015–1058, duke of Poland (c.1040–1058), son of Mieszko IIMieszko II
or Mieczyslaw II,
990–1034, king of Poland (1025–34), son and successor of Boleslaus I. His reign was marked by internal and external strife. Moravia was lost to Bohemia, Lusatia to Germany, and sections of Ruthenia to Kiev.
..... Click the link for more information. . He succeeded in reuniting the central Polish lands under the hegemony of the Holy Roman Empire, but he was never crowned king. He is also called Casimir the Restorer. His son and successor was Boleslaus II.