Zosimus, New History 2.46
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.
[2.46.1] Magnentius, perceiving that many of his enemies were thus slain, was so elated, that being now unwilling to defer the war, he mustered his forces, and immediately marched towards Pannonia. Arriving in the plain before Poetovio, through the midst of which runs the river Draus, which, passing by Noricum and Pannonia, discharges itself into the Ister, he led his troops into Pannonia, intending to engage near Sirmium. His mother is said to have enjoined him not to go that way, or over into Illyricum, but he disregarded her injunctions, though on many former occasions he had found her a true prophetess.
[2.46.2] Meantime he deliberated whether to construct a bridge over the Saus, or to pass over on boats joined together for that purpose. At the same time, Constantius sent one of the principal persons in his service, named Philip, a man of extraordinary prudence, under pretence of treating for peace and an alliance, but in reality to observe the state and disposition of the army of Magnentius, and to discover their intended movements.
[2.46.3] Approaching the camp, he met Marcellinus, the principal confidant of Magnentius, and by him was conducted to Magnentius. The army being drawn up, Philip was desired to explain the cause of his coming. Upon which he directed himself to the soldiers, telling them, that it did not become them, who were Roman subjects, to make war on Romans, especially as the emperor was the son of Constantine, with whom they had erected many trophies over the barbarians. That Magnentius, moreover, ought to remember Constantine, and the kindness he had shewn to him and to his parents. That it was Constantine who had protected him when in imminent danger, and exalted him to the highest dignities. Having made these observations, he requested Magnentius to depart from Italy, and to be content with the government of the nations beyond the Alps.