The First Council of Lyon (Lyons I) was the thirteenth ecumenical council, as numbered by the Catholic Church, taking place in 1245. The First General Council of Lyon was presided over by Innocent IV. Innocent IV, threatened by Holy Roman Emperor Frederick II, arrived at Lyon December 2, 1244, and early the following year he summoned the Church's bishops to the council later that same year. Some two hundred and fifty prelates responded including the Latin Patriarchs of Constantinople, Antioch, and Aquileia (Venice) and 140 bishops. The Latin emperor Baldwin II of Constantinople, Louis IX of France, Raymond VII, Count of Toulouse, and Raymond Bérenger IV, Count of Provence were among those who participated. With Rome under siege by Emperor Frederick II, the pope used the council to excommun