Let’s sum up Eusebius’ account. 1) Constantine reflects on the ineffective nature of the normal Roman deities, especially those to whom previous challengers of Maxentius devoted themselves. Rejecting these losing gods, Constantine considers embracing the God in whom his father believed, the Christian God (though it is historically unclear whether or not his father, Constantius, believed in Christianity); 2) Constantine prays to the God of his father to reveal himself, a request that results in the miracle of God’s sign to Constantine in the form of a cross of light and the words “Conquer by this.” 

3) Confused as to what this means, Constantine falls asleep and Christ appears to him in his dream, instructing Constantine to use the cross as a battle standard and insignia; 4) Upon waking, Constantine orders an opulent version of the cross to be constructed. The cross has on top the Greek P and X, which are the first two letters in the Greek name of Christ, and is adorned with gold, jewels and a portrait of the emperor. The structure, known as the Labarum, will become Constantine’s imperial icon; 5) Constantine follows up on his victory over Maxentius by summoning Christian bishops to teach him about the faith and with this faith conquers all remaining foes. 

Needless to say, this is a fascinating moment in world history. The scene surrounding Constantine’s dream and the dream itself, as presented by Eusebius, fuse together for the first time the history of Christianity as a religion with the history of Rome as an empire, faith with politics. Eusebius does this in both a predictable and surprising fashion, predictable because it is hard to image any other way Roman political and military life could accommodate a literal understanding of Christianity, and surprising because Christianity and Roman political and military culture represented such opposing views of the world. Roman political culture, for example, was worldly – focused on power, wealth and success. Christian doctrine in large measure rejected the world. In addition, Roman power was synonymous with military might while Christian doctrine spoke of peace. Christians believed in the rule of Christ, Romans in the rule of emperors. The Roman emperors since the days of Nero had been oppressors of the Christian minority and now all of a sudden the emperor is to be Christians’ greatest champion. From a marginal movement comprised of local groups oriented around ideas of social justice and pacifism, Christianity was suddenly at the center of the Roman imperial game – destined to become conjoined with the structures of the empire with the emperor as one of its primary leaders. Such a sweeping transformation had yet to take place in the history of Christianity in its first three centuries. 

The setting of Constantine’s conversion in a dream allows Constantine to get what he sorely needed in order to be accepted as a real convert: Christ’s personal stamp of approval. The dream setting, as we have seen in other accounts, provides the space for the divine and the human to interact – and for divine messages to be conveyed to important human actors or prophets. Constantine, in this scenario, is no prophet; rather he is presented as an agent of God and a warrior in the name of Christ. The dream allows Eusebius to overcome or transcend the tensions and contradictions in this strange marriage of Roman power with Christian faith.

By the time the famous depiction of the Battle of Milvian Bridge was painted in the Vatican in the early 16th century, the link between the Christian faith and war was fully established. Unlike in Eusebius’s day, it took no leap of faith for Renaissance Europeans to imagine a crusading Constantine.

Vatican Renaissance depiction: