Second Council of Lyon

The Second Council of Lyon was the fourteenth ecumenical council of the Catholic Church, convoked on 31 March 1272 and convened in Lyon, France, in 1272–1274.Pope Gregory X presided over the council, called to act on a pledge by Byzantine emperor Michael VIII to reunite the Eastern church with the West. The council was attended by about 300 bishops, 60 abbots and more than a thousand prelates or their , among whom were the representatives of the universities. Due to the great number of attendees, those who had come to Lyon without being specifically summoned were given "leave to depart with the blessing of God" and of the Pope. Among others who attended the council were James I of Aragon, the ambassador of the Emperor Michael VIII Palaiologos with members of the Greek clergy and the ambassadors of Abaqa Khan of the Ilkhanate. Thomas Aquinas had been summoned to the council, but died en route at Fossanova Abbey. Bonaventure was present at the first four sessions, but died at Lyon on 15 July 1274. As at the First Council of Lyons Thomas Cantilupe was an English attender and a papal chaplain.

In addition to Aragon, which James represented in person, representatives of the kings of Germany, England, Scotland, France, the Spains and Sicily were present, with procurators also representing the kingdoms of Norway, Sweden, Hungary, Bohemia, the "realm of Dacia" and the duchy of Poland. In the procedures to be observed in the council, for the first time the nations appeared as represented elements in an ecclesiastical council, as they had already become represented in the governing of medieval universities. This innovation marks a stepping-stone towards the acknowledgment of coherent ideas of nationhood, which were in the process of creating the European nation-states.