The battle of Milvian Bridge, fought on 28 October AD 312, was one of the most significant clashes in Roman history. Constantine’s victory over Maxentius gave him control of the western empire, and of the city of Rome itself. And yet the battle is more famous for something that probably did not happen. The so-called ‘Vision of Constantine’, a heavenly apparition sent to the emperor by the Christian God on the eve of battle, supposedly convinced him to convert to the new religion and laid a path for the spiritual transformation of the empire over the following century. But this vision is not mentioned in the earliest accounts of the battle at all. Two imperial panegyrics given shortly after the event make no reference to celestial manifestations, the pagan historian Zosimus ignored the story, and the Christian writer Lactantius claimed instead that the emperor was visited by God in a dream, and instructed to mark the shields of his troops with ‘the heavenly sign’.
It was the churchman Eusebius who first supplied the story of the emperor’s vision. Constantine, he claimed, had witnessed ‘with his own eyes the trophy of a cross of light in the heavens, above the sun, and bearing the inscription Conquer by This’. It is not entirely cynical, I think, to relate this anecdote to the solar apparition that Constantine reportedly saw in Gaul two or three years earlier. This vision (mentioned at the end of my previous book, Swords Around the Throne) was described at the time as a sign from the sun god. It does not seem unlikely that the Christian emperor of later years chose to reinterpret this older vision, and install Christ in the place of Apollo.
To what extent Constantine was or was not a committed Christian at the time of his Italian campaign has long been a matter of academic speculation. He may have come to see the unity of the Christian religion as a way of drawing together the various faiths and sects of the multicultural later empire under one all-powerful divine order. He may simply have believed it was true; only two years later he was declaring to a synod of bishops that ‘I myself must be judged by Christ’.
But the Roman world of the early fourth century was still resolutely traditional in its religious inclinations. The Christian population of the empire in AD 300 is estimated at between 5 and 10 per cent, concentrated in large urban centres like Carthage, Alexandria and Rome itself. This is around the same percentage as the Muslim population of Europe today. Whatever else might have motivated Constantine’s religious beliefs, they were clearly not a mere bid for popularity.
As always, in putting together a plausible description of these events I have tried to draw on as many of the more reliable ancient sources as possible. Panegyrics XII and IV, of AD 313 and 321 respectively, offer detailed, if often highly florid, blow-by-blow accounts of the action; Lactantius and Eusebius, and the later writers Zosimus and Aurelius Victor, add further – albeit often contradictory – material. Beyond this, I have tried to find expeditious solutions to the cloudier aspects of strategy and tactics: the defeat of the Maxentian clibanarii at the battle near Turin, for example, could have happened in a number of ways. I have chosen what appears to me the most likely, and happily the most dramatic too.
In the autumn of 2014 I was able to visit many of the locations of Constantine’s advance, from Susa in the Italian Alps through Turin, Milan and Verona to Rimini (ancient Ariminum) and then southwards. In the quiet little city museum of Spoleto I found the tombstone of Florius Baudio, a Protector who may well have fallen in battle while commanding Legion II Italica Divitensis; other tombstones of this same legion mark out the trail of Constantine’s advance on Rome.
The Milvian Bridge (Ponte Milvio) still crosses the Tiber to the north of the city. The probable site of the battle itself, on the plain north-east of the bridge, is bisected by highways and largely covered by military training facilities, while modern apartment blocks loom from the red stone bluffs to the west. I visited the site on the anniversary of the battle, but between the hurtling traffic streams on the Via Flaminia Nuova and Tangenziale Est I was unable to discern any echoes of that distant clash of arms. Imagination, as usual, made up the deficit.
The visitor to Rome today can admire the massive walls, repaired by Maxentius in preparation for siege, and the hulking ruins of the great Baths of Diocletian, which now house a church and a museum. Finds exhibited in the Museo Nazionale Romano, the Musei Capitolini and the Vatican attest to the opulence of aristocratic life in the fourth century. The ‘imperial regalia’ of Maxentius, presumably concealed in a cellar beneath the Palatine Hill following his defeat and only recently discovered, is now displayed in the Palazzo Massimo alle Terme.
The Arch of Constantine was erected at the heart of the city by a grateful Senate in AD 315; the vigorous frieze that runs around the main structure tells the story of the emperor’s advance, the final battle and his triumphant entry to Rome. Prominent in one of the scenes of marching troops is a baggage camel; those who doubt such animals were used by the Roman army are referred to finds of camel bones from military contexts dating to the third and fourth centuries. One even comes from the foothills of the Julian Alps.
Much of the comprehensive literature on Constantine’s campaign and defeat of Maxentius tends to dwell on the religious implications of his victory. Alongside the works mentioned in my previous books, Iain Ferris’s The Arch of Constantine provides a concise survey of the famous monument, while Raymond Van Dam’s Remembering Constantine at the Milvian Bridge is an engagingly oblique study of the various interpretations of the conflict. Neil Christie’s From Constantine to Charlemagne: An Archaeology of Italy AD 300–800 gives a detailed picture of the ancient landscape and its cities, with some invaluable maps and plans.
Maxentius has long had a bad press. His reputation was blackened by his opponents, and Christian historiography casts him as a satanic figure and a persecutor of the faithful (which he almost certainly was not). A brief, but more balanced, appraisal is offered by Mats Cullhed in Conservator Urbis Suae: Studies in the Politics and Propaganda of the Emperor Maxentius. John Curran’s Pagan City and Christian Capital: Rome in the Fourth Century, meanwhile, covers the social world of the eternal city in the later age.
There are always certain books that, found by chance, prove unexpectedly useful. This time it was Garrett G. Fagan’s Bathing in Public in the Roman World, which contains a wealth of vivid detail about the society of the great imperial bathhouses. Kyle Harper’s Slavery in the Late Roman World, AD 275–425 is an engrossing study of that most notorious, and ubiquitous, of ancient institutions.
My thanks go to Ross Cowan, for an enlightening discussion on the events of Constantine’s Italian campaign and the battles of Turin and Milvian Bridge. Once again, I offer my sincere gratitude to Rosie de Courcy for her insightful editorial support, to my agent Will Francis, and to Head of Zeus for their continued enthusiasm for my work.