Frederick succeeded Bremen's cathedral provost Ludwig von Varendorf in 1570, while his brother Henry officiated as Administrator of Bremen, Frederick was followed by Provost Theodor von Galen. During the Cologne War (1583–1589), he raised an army to fight for the Catholic faction of the cathedral chapter. He was instrumental in securing the town of Kaiserswerth in 1583 for Ernest of Bavaria, the rivalling elector-archbishop of Cologne.