Zosimus, New History 6.03
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.
[6.3.1] Some years before, Arcadius being in his sixth consulate, and Probus was his colleague,note[406 CE.] the Vandals, uniting with the Alans and the Suebi, crossed in these places, and plundered the countries beyond the Alps. Having there occasioned great slaughter they likewise became so formidable even to the armies in Britain, that they were compelled, through fear of their proceeding as far as that country, to choose several usurpers, as Marcus, Gratian, and after them Constantine.
[6.3.2] A furious engagement ensued between them, in which the Romans gained the victory, and killed most of the barbarians. Yet by not pursuing those who tied, by which means they might have put to death every man, they gave them opportunity to rally, and by collecting an additional number of barbarians, to assume once more a fighting posture.
[6.3.3] For this cause, Constantine placed guards in these places, that those tribes should not have so free access into Gaul. He likewise secured the Rhine, which had been neglected since the time of the emperor Julian.note[An incorrect statement. Valentinian has restored several forts.]