Lateran Council (769)

The Lateran Council of 769 was a synod held in the Basilica of St. John Lateran to rectify abuses in the papal electoral process which had led to the elevation of the Antipopes Constantine II and Philip. It also condemned the rulings of the Council of Hieria. It is perhaps the most important Roman council held during the 8th century.

The death of Pope Paul I, on 28 June 767, led to the uncanonical election of two antipopes. Constantine II was a layman who was elevated to the papal see by his brother Toto of Nepi and a group of Tuscan nobles. He was opposed by another antipope, Philip, who was installed by an envoy of the King of the Lombards, Desiderius and reigned just for one day, 31 July 768. With the election of Pope Stephen III on 1 August 768, and the forcible removal of the antipopes, Stephen III had sent a request to Pepin the Short, asking for bishops well versed in the Scriptures and in canon law to assist at a synod which would seek to prevent any repeat of the events that led to the elevation of the antipopes. By the time the envoys reached Francia, Pepin was dead. However, they appealed to his sons Charlemagne and Carloman, who agreed to send 12 bishops to Rome.

On 12 April 769 the Pope opened the synod in the Lateran Basilica. Present were around 52 bishops (or representatives of bishops), including ones from Tuscany and Campania, as well as a large number of priests, deacons and the laity. The council met during four sessions, spread over four days, lasting until 15 April. The first sessions of the council, lasting two days, were dedicated to reviewing the activities of the antipope Constantine II, of which Wilichar of Sens took a leading role.

...
Wikipedia