 Albert V, Duke of Bavaria, the successor of Ladislaus, resolved to restore the Catholic religion, and called in the convert and preacher, Martin Eisengrein.His intercourse with Eisengrein led Franck to an eventual conversion to Catholicism.In 1566, he matriculated at the University of Ingolstadt, devoted himself to the study of the Church Fathers and the early Christian Church, and on 25 January 1568, made a formal profession of the Catholic faith.