Zosimus, New History 4.49
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.
[4.49.1] Timasius, the commander, who admired the valor of the emperor, now desired him to permit the soldiers, who by this time were exhausted with hunger and unable to continue to toil in the marshes, to refresh themselves. To this the emperor assented, and the trumpet sounded a retreat, upon which the soldiers ceased pursuing the barbarians. When they had abundantly satisfied themselves with eating and drinking, they were so overpowered with wine and fatigue that they fell asleep.
[4.49.2] This being observed by the remaining barbarians, they seized their arms, and falling on the soldiers, who were already subdued by sleep and intoxication, they pierced them with their spears and swords, and other instruments of death. The emperor himself with his whole army were in the most imminent danger of death, had not some, who had not yet dined hastened to the tent of the emperor, and informed him of the circumstance. The emperor and those who were with him, being considerably alarmed, resolved to avoid the impending danger by a precipitate flight.
[4.49.3] But being met, as they were escaping, by Promotus, who had been sent for by the emperor, he desired the emperor to consult his own safety and that of those who were with him; as he himself would attend to the barbarians, and punish them as for their obstinacy they deserved. He had no sooner said this, than he hastened to the barbarians, whom he found still among the sleeping soldiers, and slew so many of them, that scarcely any of them escaped with safety into the marshes.