Sixtus V sent him as his Apostolic Nuncio in France in May 1587. In the France scarred by the Wars of Religion, the duty of the Nuncio was to support the politic of Catherine de' Medici in trying to ally Henry III with the Catholic League led by the Henry I, Duke of Guise against the Huguenots. To support the Catholic war he was allowed by the Pope to sell estates of the Church, but this was fiercely opposed by the French clergy. Nor he succeeded to have the decrees of the Council of Trent published in French. He asked to the Pope to side with Henry III against the Duke of Guise, but this position was not supported by the Pope who more and more became displeased of his nuncio. In the events of the Day of the Barricades he tried to riconciliate the leaders of the Catholic League with Henry III. A few months later, the murders of Louis II, Cardinal of Guise and of the Duke of Guise by order of Henry III marked the failure of his politic.