Constantine

Roman emperor, AD 306–337died 22 May AD 337Also: Constantine the Great, Constantine I

Emperor proclaimed by his father’s army at York in 306. After defeating Maxentius at the Milvian Bridge in 312 he favoured the Christian church, became sole ruler, summoned the Council of Nicaea, founded Constantinople, and was baptised shortly before his death.

Constantine was the son of the emperor Constantius and of Helena, and was brought up at Naissus. He was kept as a hostage at the court of Diocletian and Galerius, rejoined his father in Gaul, and was hailed as Caesar by the troops when Constantius died at York (Origo Constantini 1.1–2.4). In 312 he marched on Rome and defeated Maxentius at the Milvian Bridge, after a dream in which, Lactantius says, he was told to mark his soldiers’ shields with the sign of Christ (Lactantius, Deaths of the Persecutors 44). The next year he and Licinius agreed at Milan that Christians and all others should be free to follow their own religion (Lactantius, Deaths of the Persecutors 48).

He defeated Licinius and became sole emperor, and renamed Byzantium Constantinople (Origo Constantini 5.23–6.30). He called the bishops together at Nicaea (Eusebius, Life of Constantine 3.6). Eusebius reports that he was baptised only in his last illness, in the suburbs of Nicomedia, and died at Pentecost (Eusebius, Life of Constantine 4.61–64). The historian Socrates, a century later, gives the day, 22 May 337, and a reign of thirty-one years (Socrates, Church History 1.39–40).

In the timeline

Constantine’s Victory at the Milvian Bridge

Constantine defeats Maxentius outside Rome and becomes master of the western empire. Christian writers say that he fought under a sign of Christ shown to him beforehand, in a dream according to Lactantius, in the sky according to the later account of Eusebius.

The Edict of Milan

Constantine and Licinius agree at Milan that Christians and everyone else may worship as they choose. The text that survives is a letter Licinius had posted at Nicomedia in June 313, which also orders confiscated church property returned.

The Donatist Schism and the Council of Arles

Two rival bishops claim Carthage after the persecution. One party appeals to Constantine, who refers the case to bishops at Rome and then to a council at Arles. Both find for Caecilian, but the African church is still divided ninety years later.

The First Council of Nicaea

Constantine gathers some three hundred bishops at Nicaea over the teaching of Arius. They confess the Son to be “of one substance with the Father”, agree a common date for Easter and issue twenty canons. Catholic, Orthodox and Reformation churches still appeal to the council.

Constantine Dedicates Constantinople

Constantine rebuilds Byzantium on the Bosphorus as a new imperial city, names it after himself and dedicates it on 11 May 330. He means it to equal Rome and calls it New Rome, and in 381 its bishop is ranked next after the bishop of Rome.

The Church of the Holy Sepulchre Is Dedicated

Constantine has a temple cleared from the site in Jerusalem where a rock tomb is uncovered, and builds a great basilica beside it. Bishops from across the East dedicate it in 335. Later writers add that his mother Helena found the cross there.

Constantine

In the timeline

Primary sources

The Origin of the Emperor Constantine

On the Deaths of the Persecutors

Life of Constantine

Church History