Bolesław's son and heir, Duke Henry the Bearded had to cede the Opole lands to his uncle and also renounced any inheritance claims to Mieszko's Upper Silesian duchies.

In 1215, at the Congress of Wolbórz, Casimir I gave to the church great privileges and immunity, which was the origin of the semi-independent district of Ujazd, then property of the Wrocław diocese.

Casimir's extensive cooperation with the church also provided him with security against the ambitions of his neighbors; however, this only served to protect Racibórz: the lands of Opole were in conflict with the Lower Silesian duke Henry I the Bearded; and the Lesser Polish estates of Siewierz, Bytom and Oświęcim were disputed by the Seniorate in Kraków.

After this year, the help of emigrants, like Klement of Brzeźnica (member of the Gryficis)-who took on part of the costs of building the city walls of Opole-proved to be good for Casimir I.

Casimir I died suddenly on 13 May 1230 (although some historians put his death one year earlier) and was buried in the still unfounded Czarnowąsy (Czarnowanz) monastery, which was generously patronized by him.

They had four children:[1][2] After Casimir I's death, Henry I the Bearded assumed the regency and formal guardianship of his minor sons, while his widow Viola took over direct tutelage of them.