Константинопольский собор
At least three councils – Council of Constantinople (867), Fourth Council of Constantinople (Roman Catholic) (869), and Fourth Council of Constantinople (Eastern Orthodox) (879) – were held in Constantinople over the actions of Emperor Michael III in deposing Ignatius and replacing him with Photius. The Council of Constantinople (867) was convened by Photius to address the question of Papal Supremacy over all of the churches and their patriarchs and the use of the "Filioque".