Mieszko I of Poland the Czechs took over Meissen, but in the same year Henry II gave up his pretension to the German throne. The role played by Mieszko I in the subsequent struggles is unclear because the contemporary sources are scarce and not in agreement. Probably in 985 the Polish ruler ended his support for the Bavarian duke and moved to the side of the Emperor. It is believed that Mieszko's motivation was the threat posed to his interests by the Polabian Slavs uprising. The upheaval was a problem for both Poland and Germany, but not for Bohemia. In the "Chronicle of Hildesheim",
Mieszko Kazimierzowic "Gesta principum Polonorum" written in the early 12th century, put Mieszko third in order, among his brother. Modern historian, Janusz Bieniak, has supposed that Mieszko was the second son of Casimir I and was older than Władysław Herman, but most scholars disagree with this hypothesis. The date of Mieszko's birth was given by "Rocznik krakowski" (Kraków Annals). This source omitted dates of birth of Mieszko's brothers. Kazimierz Jasiński thought that "Rocznik" was started shortly before Mieszko's birth and this was the reason for absence of his older brothers. Przemysław Wiszewski supposed tha Casimir I chose Mieszko as his successor and