mid-9th century

The Donation of Constantine and the Pseudo-Isidorian Decretals

In the mid-9th century the clergy of Le Mans compiled a collection of genuine and fabricated papal decrees. They issued it under the name of Isidore of Seville. The aim was to shield bishops from the encroachments of secular nobles and archbishops. To this end the collection gave papal claims a spurious antiquity, supposedly going back to the 3rd century.

Together with another famous forgery, the Donation of Constantine, the decretals supported the theory that all bishops were subject to the pope.

The forgery of the decretals was exposed only a century later. But by then they had already become a foundation of papal claims, especially under Pope Nicholas I. The Donation of Constantine was unmasked in the 15th century by Lorenzo Valla.