Obv: IMP POSTVMVS (bust of Postumus)
Rev: VIRTVS EQVIT - Mars, walking right, holding spear and shield
T in exergue
RIC (Postumus) 388
Aureolus was a brilliant military leader, tapped by the emperor Gallienus to put down the rebellion by Postumus. Shamed and demoted after allowing the usurper to escape, he temporarily switched sides and threw in his lot with Postumus (hence this coin minted in honor of Postumus) and his breakaway republic. He attempted to reconcile with Claudius Gothicus, the new emperor after the murder of Gallienus, but was murdered by Claudius’ praetorian guards.
Note: There may not be any coins that contain an image or even the name of Aureolus on them. The few that exist are all controversial and possibly tooled or forgeries. Current scholarship is pretty much in agreement, though, that this series from the Mediolanum (Milan) mint were all minted by Aureolus in an attempt to gain the recognition and support of Postumus.