Belisarius, having sent out Constantine and Bessas with a small force to win Tuscany over to our arms, set his remaining troops to work at strengthening the ancient city ramparts, clearing and deepening the choked fosse, and patching up the gates. Since early in Theoderich's reign no one had troubled about the repair of the ramparts. They consisted of the customary broad terrace of earth enclosed between two battlemcnted walls, with guard-towers at intervals. Belisarius now improved on the battlements by adding a defensive wing to each of them, on the left; so that to birds or angels looking down from the sky they would appear like the letter Gamma written many times over. He employed all the available masons and labourers in the city on this work, as he had done at Carthage. He also filled the Roman granaries with corn that he had brought from Sicily and requisitioned all stocks of grain within 100 miles of the city; paying for them at a fair price.
We had entered Rome on the tenth day of December; three months were gone before King Wittich came against us with his army. But by then it was a very strong army, drawn from every part of Italy and from across the Alps – consisting for the most part of heavy cavalry. Tuscany had yielded to our arms, but Belisarius now recalled from there all but the garrisons which he had put into Perugia and Narni and Spoleto, a mere thousand men. With the marines whom he took from the fleet, he had 10,000 men of all arms to oppose to 150,000 Goths. Thus the siege of Rome began.
Wittich rode southward at the head of his army, which strung out behind him on the Flaminian Way for a hundred miles and with only a little interval between division and division. Not far from Rome, he met a priest being carried out from the city in a sedan-chair on his way to take up a bishopric in the North. Wittich asked this priest:' What news, Holy Father? Is Belisarius still at Rome? Do you think that we shall catch him before he falls back on Naples?'
The priest, who was a man of penetration, replied: 'There is no need to hurry, King Wittich. The Lady Antonina, wife of this Belisarius, is reglazing the windows of a palace which they are to occupy, and putting new hinges on the doors and buying furniture and pictures, and re-planting the garden with rose-trees and building a new north porch. Belisarius himself is doing the same sort of thing for the city defences – when you reach the Tiber you will find a new sort of north porch that he has built at the Mulvian Bridge.'
There are many bridges over the Tiber. The Mulvian is the only one near Rome that is not part of the city fortifications, lying two miles to the northward. Belisarius had built two strong stone towers here and garrisoned them with a detachment of 150 cavalrymen; whom he provided with catapults and scorpions to sink any boat in which the Goths might attempt to cross the river and take them in the rear. He intended the fortification of this bridge to delay Wittich's advance, obliging him cither to make a long detour or to send his men across the river by tens or twenties in a few small ferry-boats – he had removed all larger boats and barges himself. Whichever choice Wittich made, his army was so huge that Belisarius would gain something like twenty clays for completing his work on the city fortifications; and in those twenty days the reinforcements that he was expecting from Constantinople might well arrive. Perhaps he would also be able to delay the enemy's crossing at another point.
The Mulvian Bridge garrison proved cowardly. When they saw the Gothic knights approaching in their hundreds and thousands and tens of thousands, mounted on fine horses, the spring sunshine twinkling on helmets and armour and lance-points and frontlets and poitrails, they said to one another: 'Why should we stay here and be killed to please Belisarius? Not even he would care to face the odds of a thousand to one.' Some of them were Thracian Goths, who suddenly realized that this impressive army consisted of their kinsmen and co-religionists. What quarrel had they with them? At dusk the garrison lied: the Thracian Goths as deserters to Wittich, the remainder in the direction of Campania, being ashamed or afraid to return to Rome.