Mieszko II Lambert the help of foreign forces. Probably the brother who caused the first problems to Mieszko II was Bezprym, who allegedly with the support of Otto won the alliance of Kiev in order to take power. When Mieszko II was busy defending Lusatia from the troops of Conrad II, the Kievan expedition started from the east with Yaroslav I the Wise as the leader. In 1031 Poland was invaded and then Bezprym was settled on the throne. Mieszko II and his family were forced to flee the country. Queen Richeza and her children found refuge in Germany. The King couldn't escape
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