After long-lasting quarrels with the mighty Brandenburg prince-electors, the Premonstratensian chapter finally gave in to transform Havelberg into a collegiate church ("Stift"). From 1514 onwards the deans of the cathedral were appointed by the Margraves of Brandenburg. In the course of the Protestant Reformation, the Bishopric of Havelberg turned Lutheran and from 1554 was administrated by Joachim Frederick of Hohenzollern, son of Elector John George of Brandenburg. The Bishopric was finally secularised and incorporated into Brandenburg in 1571. Its annexation was complete, when Joachim Frederick succeeded his father as Brandenburg elector in 1598.