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 I of Poland copying the document he made a mistake and wrote down Dagome instead of Dagomer or even Dagomir. The name Dagomir is used to this day and its construction is similar to other Polish names like for example: Władimir/Włodzimierz or Casimir/Kazimierz. The evolution of the "-mir" element to "-mierz" is due to two separate developments: first, the regular change of the vowel "i" to "(i)e" before "r", and second, the modification of the nominative case by the vocative for certain names (hence, Kazimierz replaced Kazimier based on the vocative Kazimierze). It is debatable whether the name Mieszko is a nickname formed