In the history of Christianity, the first seven ecumenical councils, from the First Council of Nicaea (325) to the Second Council of Nicaea (787), represented an attempt to reach an orthodox consensus and to restore, continue and develop a unified Christendom. The East–West Schism, formally dated to 1054, would become definitive almost three centuries after the last of these councils, but already by 787 the major western sees, although still in communion with the state church of the Byzantine Empire, were all politically outside the Empire, and the Pope was to crown Charlemagne as a western emperor 13 years later.