Zosimus, New History 6.02
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.
[6.2.1] When Arcadius was reigning, Honorius being consul the seventh time and Theodosius the second, the troops in Britain revolted and promoted Marcus to the imperial throne, rendering obedience to him as the sovereign in those countries. Some time subsequently, having put him to death for not complying with their inclinations, they set up Gratian, whom they presented with a diadem and a purple robe, and attended him as an emperor.
[6.2.2] Being disgusted with him likewise, they four months afterwards deposed and murdered him, delivering the empire to Constantine. He having entrusted to Justinian and Nebigast the command of the Celtic legions, crossed over from Britain. Having arrived at Bononia, which is the nearest to the sea-side, situated in the lower Germany, and continuing there some days, he conciliated the attachment of all the troops between that place and the Alps, which separate Gaul from Italy, thus appearing now secure in the empire.
[6.2.3] At the same time Stilicho sent Sarus at the head of an army against Constantine. Having encountered with the division commanded by Justinian, he slew that general with the greater part of his soldiers. Having acquired great spoils he advanced to besiege Valentia, where he understood that Constantine had placed himself, it being a strong city, well fortified and a secure residence.
[6.2.4] Nebiogast, the surviving commander, having made overtures of peace to Sarus, was received by him as a friend. But Sarus, although he had both given and received an oath to the contrary, immediately put him to death, without regard to what he had sworn.
[6.2.5] Constantine then conferred the command, vacant by the death of Justinian and Nebiogast, on Edobinch, a Frank by extraction, but a native of Britain, and on Gerontius, a Briton. Sarus, being in dread of the courage and the military experience of these two, raised the siege of Valentia after he had continued in it seven days.
[6.2.6] The officers of Constantine attacked him so briskly, that he had much difficulty to escape with life, and was under the necessity of giving up all his spoils to the Bacaudae, a tribe of freebooters, to allow him to pass into Italy.
[6.2.7] When Sarus was thus safely returned to Italy, Constantine, having mustered all his forces, resolved to place a sufficient guard on the Alps in the three passes, which form the passage from Italy into Celtica, commonly termed the Cottian, the Pennine, and the maritime Alps. This was the reason for his taking these precautions.