The Second Ecumenical Council, also known as the First Council of Constantinople, took place in 381 AD. It was convened by Emperor Theodosius I to address various theological disputes and to affirm the Nicene Creed established at the First Ecumenical Council in 325 AD. This council aimed to clarify the nature of the Holy Spirit and counter the teachings of the Arian controversy. The council brought together bishops from across the Roman Empire, resulting in the condemnation of several heresies. It also established the authority of the Bishop of Constantinople, enhancing the city's role in the early Christian Church. The decisions made at this council significantly shaped Christian doctrine and ecclesiastical structure.