contra hunc ipse Gallienus exercitum duxit; cumque urbem, in qua erat Postumus, obsidere coepisset, acriter eam defendentibus​ Gallis, Gallienus muros circumiens sagitta ictus est.
Translation :
Thereupon Gallienus himself led his army against him, and when he began to besiege the city in which Postumus was, the Gauls defended it bravely, and Gallienus, as he went around the walls, was struck by an arrow.
Edition :
Historia Augusta, Volume III: The Two Valerians. The Two Gallieni. The Thirty Pretenders. The Deified Claudius. The Deified Aurelian. Tacitus. Probus. Firmus, Saturninus, Proculus and Bonosus. Carus, Carinus and Numerian. Translated by David Magie. Loeb Classical Library 263. Cambridge, MA: Harvard University Press, 1932.