Gallienus

Gallienus led Roman forces to victory against the Alemanni who had invaded Italy and reached Mediolanum (Milan). The victory secured northern Italy from Germanic incursions and demonstrated Gallienus's military capability during the Crisis of the Third Century.

After his father Valerian's capture, Gallienus reorganized the Roman army by creating a mobile cavalry force (vexillationes) under commanders like Aureolus. He also promoted equestrians over senators for military commands, reducing senatorial influence and improving military efficiency.

Gallienus issued an edict ending the persecution of Christians that had been enforced under his father Valerian. He restored Christian property and allowed freedom of worship, marking a shift in imperial policy toward Christianity before the later Edict of Milan.

Gallienus was murdered by his own officers while besieging the usurper Aureolus at Mediolanum. The conspiracy was led by Claudius, who succeeded him as emperor. Gallienus's death ended a 15-year reign that held the empire together during its deepest crisis.