Res Gestae

But while these well-laid plans were being hurried on, the Laeti, a savage tribe skilled in seasonable raids, passed secretly between the encampments of both armies and made an unlooked for attack on Lyons; and with their sudden onset they would have sacked and burned the town, had they not been driven back from the closed gates but made havoc of whatever they could find outside the town.

This disaster was no sooner known than Caesar, with quick grasp of the situation, sent three squadrons of brave light cavalry and watched three roads, knowing that the raiders would doubtless burst forth by them; and his ambuscade was not in vain.

For all who passed out by those roads were butchered and all their booty recovered intact, and only those escaped unharmed who made their way undisturbed past the rampart of Barbatio; being allowed so to slip by because Bainobaudes, the tribune,

And not content with that, the infantry commander, who was a coward and a persistent detractor of Julian’s reputation, knowing that what he had ordered was against the interests of the Roman cause (for when Cella was charged with this, he confessed it), deceived Constantius in his report and pretended that these same tribunes had come, under the pretext of public business, to tamper with the soldiers whom he had been commanding; and for that reason they were cashiered and returned to their homes in a private capacity.