"He was the second son of Bolesław I the Brave but the eldest born from his third wife Emnilda of Lusatia. He was probably named after his paternal grandfather, Mieszko I. His second name, Lambert, sometimes erroneously considered to be a nickname, was given to him as a reference to Saint Lambert. Also, it is probable that this name Lambert was chosen after Bolesław´s half-brother Lambert. It is thought that the choice of this name for his son was an expression of warming relations between Bolesław I and his stepmother Oda.
He organized two devastating invasions to Saxony in 1028 and 1030. Then Mieszko II ran a defensive war against Germany, Bohemia and the Kievan princes. Mieszko II was forced to escape from the country in 1031 after an attack of Yaroslav I the Wise, who installed Mieszko´s older half-brother Bezprym onto the Polish throne. Mieszko took refuge in Bohemia, where he was imprisoned by the Duke Oldrich. In 1032 he regained power in one of the three districts, then united the country, making good use of the remaining power structures. At this time, several Polish territorial acquisitions of his father were lost: Upper Lusatia (also known as Milsko), part of Lower Lusatia, Red Ruthenia, western and central part of Upper Hungary (now Slovakia) and probably Moravia." - (en.wikipedia.org 16.11.2019)
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