AD 312 – Milvian Bridge: Rome’s Great Battle for Empire and Church
By Ross Cowan
Military History Monthly (June 2012)
Introduction: Seventeen hundred years ago, the emperor Constantine marched on Rome. His propaganda spoke of freeing Italy and the Eternal City from the tyrant Maxentius. But the real aim of this supremely ambitious and deeply religious man was the conquest and reunification of the Roman Empire. There would be one empire, one ruler, and henceforth, one faith.
The army marched from Trier in spring AD 312. Legons and elite cavalry regiments called vexillations were at its core. Auxiliary regiments, of lesser prestige in the Roman military hierarchy but still fearsome in battle, brought the strength of the expeditionary force to just under 40,000 fighting men. It was a pagan army that marched under eagle and dragon standards, but at its head rode an emperor with growing Christian sympathies.
For the pagan soldiers, Constantine’s preferred deity was less important than his marks of divine favour. Since his elevation to the throne by the army at York in AD 306, the emperor’s victories over the Germans had provided ample evidence of the favour of the gods – or perhaps a god. Constantine, moreover, was charismatic and genuinely concerned for the welfare of his soldiers. It was in these early campaigns that he endeared himself to them as their ‘fellow-veteran’.
Constantine’s hold over his army is demonstrated by the first battle of the campaign of AD 312. Having marched south to Lyon, and thence to Vienne, the army crossed the Alps and descended on Susa in north-west Italy. The Maxentian garrison barred the gates of the fortress city and manned the ramparts.