Through the preachings of the Bishop of Samland, Georg von Polenz, Königsberg became predominantly Lutheran during the Protestant Reformation. After summoning a quorum of the Knights to Königsberg, Grand Master Albert of Brandenburg (a member of the House of Hohenzollern) secularised the Teutonic Knights' remaining territories in Prussia in 1525 and converted to Lutheranism. By paying feudal homage to his uncle, King Sigismund I of Poland, Albert became the first duke of the new Duchy of Prussia, a fief of Poland.