Complex sentence: The persecutions began in the Bishopric of Würzburg, under the leadership of Prince-Bishop Phillip Adolf von Ehrenberg, an ardent devotee of the Counter-Reformation, who was eager to assert Catholic authority in the territories he administered.
Split into simpler sentences: The persecutions began in the Bishopric of Würzburg, under the leadership of Prince-Bishop Phillip Adolf von Ehrenberg. An ardent devotee of the Counter-Reformation, von Ehrenberg was eager to solidify Catholic authority in the territories he administered.