Mieszko II Lambert of Pöhlde asked the Emperor to defend against the attacks of Mieszko II, promising support in the fight against the Polish ruler. Despite the treaty which secured peace between Poland and Germany, the Emperor soon armed a retaliatory expedition against Mieszko II. Conrad II's army arrived to Lusatia in the autumn of 1029 and began the siege of Bautzen; but the German troops did not receive the promised support of the Lutici tribe and the expedition failed. Threatened by the Hungarians, the Emperor was forced to retreat. Probably in this same year the son of Oldřich, Bretislaus I, attacked and
Mieszko I of Poland been between 922–945; the activity of the Duke in his final years of life puts the date of his birth closer to the latter year. There are three major theories concerning the origin and meaning of Mieszko I's name. The most popular theory, proposed by Jan Długosz, explains that Mieszko is a diminutive of "Mieczysław", a combination of two elements or lexemes: "Miecz" meaning sword and "Sław" meaning famous. Today, this theory is rejected by the majority of Polish historians, who consider the name Mieczysław to have been invented by Długosz to explain the origin of the name Mieszko. Today,