Trierer Dom
Following the death of Archbishop of Trier Johann von Schönenberg, the cathedral chapter of the Cathedral of Trier elected Metternich as coadjutor archbishop on 7 August 1599. Pope Clement VIII confirmed his appointment on 11 October 1599. Bishop emeritus of Osor Coriolani Garzadori consecrated Metternich as a bishop on 30 July 1600 in the church dedicated to Florinus of Remüs in Koblenz.