Casimir I the Restorer not supported by modern historians. Regardless, he left church work for good in 1031. Casimir's father, Mieszko II, was crowned King of Poland in 1025 after the death of his father Bolesław I the Brave. However, the powerful magnates of the country feared a strong central government like the one that existed under Bolesław I's rule. This led to considerable friction between the King and the nobility. Taking advantage of the King's precarious situation, Mieszko II's older half-brother Bezprym and younger brother Otto turned against him and allied themselves with the Holy Roman Emperor Conrad II, whose forces attacked Poland
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