Zosimus, New History 4.42
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.
[4.42.1] Affairs being thus situated in the east, in Thrace, and in Illyricum, Maximus, who deemed his appointments inferior to his merits, being only governor of the countries formerly under Gratian, projected how to depose the young Valentinian from the empire, if possible totally, but should he fail in the whole, to secure at least some part.
[4.42.2] Full of this resolution, he prepared to cross the Alps into Italy. Perceiving, however, that it would be necessary for him to pass through narrow defiles, and over craggy and pathless mountains, and beyond these, through morasses and fens which admit of no passengers, except those who travel very slowly, much less of so considerable an army, he deferred the enterprise until he could form better measures.
[4.42.3] Valentinian, however, sending ambassadors from Aquileia to desire a continuance of peace, Maximus complied with his request, and pretended to be gratified with the proposal. Valentinian, therefore, sent Domninus to treat, who, though by birth a Syrian, was a steady friend to the emperor.
[4.42.4] As he was next to the emperor in authority, he seemed likewise to excel all others in fidelity and experience, and whatever private measures he wished to adopt, he imparted to this person alone. When Domninus arrived with Maximus, and had informed him of the motive of the embassy, he was received with the utmost kindness and respect. Maximus conferred on him so great honors, and so many presents, that Domninus supposed that Valentinian would never again have so good a friend.
[4.42.5] To such a degree did Maximus succeed in deluding Domninus, that he sent along with him part of his own army to the assistance of the emperor against the barbarians, who dreadfully oppressed the Pannonians under his dominion. Domninus departed from him highly gratified not only by the many presents he had received, but at being accompanied by those were sent with him. He therefore imprudently by crossing the Alps rendered the passage more practicable to Maximus.
[4.42.6] That he would do this had been foreseen by Maximus, who had therefore made every preparation, and followed him with all his forces. He moreover detached guards before him, to prevent the passage of any that way, who might give intelligence to the attendants of Domninus, that Maximus was penetrating into Italy. This precaution had its full success, it being impossible for any person to pass through the narrow defile of the mountains without being perceived.
[4.42.7] Upon learning that Domninus and his retinue had passed the defiles of the Alps and the marshes beyond them, which are extremely difficult for the march of an army, not fearing to meet any enemy in those devious places, he immediately entered Italy without; resistance, and marched to Aquileia.