Ammianus Marcellinus Res Gestae 29.5.37

[37] Theodosius, ¹ sparing none of the enemy who came near, after refreshing his soldiers with better food and their pay, as well as disposing of the Caprarienses and their neighbours the Abanni in a slight skirmish, hastened to the municipal town of Audia. ² But having learned from trustworthy sources that the savages had already taken possession of hills which extended upwards in all directions in winding masses, and could be penetrated by no one except natives who were thoroughly acquainted with the locality, he retreated and thereby during the cessation of hostilities, brief though it was, gave the enemy an opportunity of being strengthened by very numerous auxiliaries from the Aethiopians who dwelt near by.