The First Council of Constantinople was a council of Christian bishops convened in Constantinople in AD 381 by the Roman Emperor Theodosius I. This second ecumenical council, an effort to attain consensus in the church through an assembly representing all of Christendom, except for the Western Church, confirmed the Nicene Creed, expanding the doctrine thereof to produce the Niceno-Constantinopolitan Creed, and dealt with sundry other matters. It met from May to July 381 in the Church of Hagia Irene and was affirmed as ecumenical in 451 at the Council of Chalcedon.
Theodosius I, also known as Theodosius the Great, was a Roman emperor from 379 to 395. He won two civil wars and was instrumental in establishing the Nicene Creed as the orthodox doctrine for Nicene Christianity. Theodosius was the last emperor to rule the entire Roman Empire before its administration was permanently split between the Western Roman Empire and the Eastern Roman Empire. He ended the Gothic War (376–382) with terms disadvantageous to the empire, with the Goths remaining within Roman territory but as nominal allies with political autonomy.
Valens was Roman emperor from 364 to 378. Following a largely unremarkable military career, he was named co-emperor by his elder brother Valentinian I, who gave him the eastern half of the Roman Empire to rule. In 378, Valens was defeated and killed at the Battle of Adrianople against the invading Goths, which astonished contemporaries and marked the beginning of barbarian encroachment into Roman territory.
The 400s decade ran from January 1, 400, to December 31, 409.
The 380s decade ran from January 1, 380, to December 31, 389.
The 390s decade ran from January 1, 390 to December 31, 399
The 440s decade ran from January 1, 440, to December 31, 449.
The 360s decade ran from January 1, 360, to December 31, 369.
The 340s decade ran from January 1, 340, to December 31, 349.
The 370s decade ran from January 1, 370, to December 31, 379.
Year 380 (CCCLXXX) was a leap year starting on Wednesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Augustus and Augustus. The denomination 380 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Fritigern was a Thervingian Gothic chieftain whose decisive victory at Adrianople during the Gothic War (376–382) led to favourable terms for the Goths when peace was made with Gratian and Theodosius I in 382.
St. Flavian I of Antioch was a bishop or Patriarch of Antioch from 381 until his death.
Saint Meletius was a Christian bishop of Antioch from 360 until his death in 381. He was opposed by a rival bishop named Paulinus and his episcopate was dominated by the schism, usually called the Meletian schism. As a result, he was exiled from Antioch in 361–362, 365–366 and 371–378. One of his last acts was to preside over the First Council of Constantinople in 381.
Nectarius of Constantinople was the archbishop of Constantinople from 381 until his death, the successor to Saint Gregory of Nazianzus and predecessor to John Chrysostom.
In historiography, the Late or Later Roman Empire, traditionally covering the period from 284 CE to 641 CE, was a time of significant transformation in Roman governance, society, and religion. Diocletian's reforms, including the establishment of the tetrarchy, aimed to address the vastness of the empire and internal instability. The rise of Christianity, legalized by Constantine in 313 CE, profoundly changed the religious landscape, becoming a central force in Roman life. Simultaneously, barbarian invasions, particularly by the Goths and Huns, weakened the Western Roman Empire, which collapsed in 476 CE. In contrast, the Eastern Roman Empire endured, evolving into the Byzantine Empire and laying the foundations for medieval Europe.
The Edict of Thessalonica, issued on 27 February AD 380 by Theodosius I, made Nicene Christianity the state church of the Roman Empire. It condemned other Christian creeds such as Arianism as heresies of "foolish madmen," and authorized their punishment.
In the year before the First Council of Constantinople in 381, Christianity became the official religion of the Roman Empire when Theodosius I, emperor of the East, Gratian, emperor of the West, and Gratian's junior co-ruler Valentinian II issued the Edict of Thessalonica in 380, which recognized the catholic orthodoxy of Nicene Christians as the Roman Empire's state religion. Historians refer to the Nicene church associated with emperors in a variety of ways: as the catholic church, the orthodox church, the imperial church, the Roman church, or the Byzantine church, although some of those terms are also used for wider communions extending outside the Roman Empire. The Eastern Orthodox Church, Oriental Orthodoxy, and the Catholic Church all claim to stand in continuity from the Nicene church to which Theodosius granted recognition.
Paulinus II was a claimant to the See of Antioch from 362 to 388.
Athanaric or Atanaric was king of several branches of the Thervingian Goths for at least two decades in the 4th century. Throughout his reign, Athanaric was faced with invasions by the Roman Empire, the Huns and a civil war with Christian rebels. He is considered the first king of the Visigoths, who later settled in Iberia, where they founded the Visigothic Kingdom.
