The First Council of Constantinople occurred in AD 381 in the city of the same name (modern Istanbul, Turkey). It is considered the second of the Ecumenical Councils, after Nicea in 325. At the Council of Constantinople, Christian bishops convened to settle several doctrinal disputes prompted by unrest in the religious leadership of the city. While not as memorable as the Council of Nicea, the council dealt a fatal blow to Arianism, clarified the language used to describe the Trinity, and sharpened the distinctions between the Eastern and Western branches of the church.