Mieszko II Lambert by the chronicles of Gottfried of Viterbo, refers to Bezprym. However, the historians now think that he was killed in a plot hatched by the aristocracy. He was buried in the Cathedral of St. Peter and St. Paul. After Mieszko II's death, Poland's peasants revolted in a "pagan reaction." The exact reasons and date are unknown. Mieszko II's only son and heir, Casimir I, was either expelled by this insurrection, or the insurrection was caused by the aristocracy's expulsion of him. Some modern historians argue that the insurrection was caused more by economic than by religious issues, such as new
Mieszko III the Old of the rebels and divided Henry's Duchy in three parts: Wiślica Land was taken by Casimir, Bolesław took Sandomierz proper, and the rest was led to Mieszko. In 1172 another conflict arose among the Silesian Piasts, when Duke Bolesław the Tall chose to ignore the claims of his first-born son, Jaroslaw by designating his son of the second marriage Henry I the Bearded his sole heir. When Jarosław, forced to become a priest, had returned from his German exile, he claimed a share of the Silesian lands. Mieszko III supported his grandnephew in his demands, and the civil war was