In 1587 he was appointed Apostolic Nuncio to Cologne, which was then in the midst of the Cologne War. He was appointed bishop of Tricarico on 9 March 1592, while in Cologne, but did not visit the diocese. As a result of his experience in Cologne he pressed for the creation of a nunciature in Brussels, arriving there as nuncio on 11 February 1596. He was active in promoting the restoration of Catholic life in the war-torn Southern Netherlands, visiting Antwerp, Arras, Liège, Namur, Tournai, Cambrai, Calais, Lille, Dunkirk and Gravelines.