As countess of Ostfriesland, Catherine took an active part in policy and the affairs of state.[1] She supported Edzard in his conflict with his brother John over the rule of the divided Ostfriesland, while John had the support of his mother Anna.[2] The conflict also had a religious dimension, as Edzard and Catherine were Lutherans, while John and Anna were Calvinists.[2] She worked to secure a new succession which banned co-ruling, and she actively supported Lutheranism before Calvinism.[2]