Zosimus, New History 2.16
Zosimus (Greek Ζώσιμος): Early Byzantine, pagan author of a history of the Roman Empire, published in the first quarter of the sixth century CE.
The translation of Zosimus' New History offered here was printed in 1814 by W. Green and T. Chaplin in London, and was probably prepared by J. Davis of the Military Chronicle and Military Classics Office. The translator is anonymous. The text was found at Tertullian.org. The notes were added by Jona Lendering.
[2.16.1] Constantine, advancing with his. army to Rome, encamped in a field before the city, which was broad and therefore convenient for cavalry. Maxentius in the mean time shut himself up within the walls, and sacrificed to the gods, and, moreover, consulted the Sibylline oracles concerning the event of the war. Finding a prediction, that whoever designed any harm to the Romans should die a miserable death, he applied it to himself, because he withstood those that came against Rome, and wished to take it.
[2.16.2] His application indeed proved just. For when Maxentius drew out his army before the city, and was marching over the bridge that he himself had constructed, an infinite number of owls flew down and covered the wall. When Constantine saw this, he ordered his men to stand to their arms. And the two armies being drawn up opposite to each other, Constantine sent his cavalry against that of the enemy, whom they charged with such impetuosity that they threw them into disorder.
[2.16.3] The signal being given to the infantry, they likewise marched in good order towards the enemy. A furious battle having commenced, the Romans themselves, and their foreign allies, were unwilling to risk their lives, as they wished for deliverance from the bitter tyranny with which they were burdened, though the other troops were slain in great numbers, being either trod to death by the horse, or killed by the foot.
[2.16.4] As long as the cavalry kept their ground, Maxentius retained some hopes, but when they gave way, he tied with the rest over the bridge into the city. The beams not being strong enough to bear so great a weight, they broke; and Maxentius, with the others, was carried with the stream down the river.