Postumus vs Zeno

Following the capture of Emperor Valerian by the Sassanids, Postumus was proclaimed emperor by his troops in Gaul. He established the Gallic Empire, a breakaway state comprising Gaul, Britain, and Hispania, with its capital at Colonia Agrippina.

Postumus repelled an invasion by Emperor Gallienus, defeating him at the Battle of Mursa. This victory secured the Gallic Empire's independence and forced Gallienus to abandon attempts to reconquer the western provinces.

Postumus successfully defended the Gallic Empire against both internal usurpers and external Germanic invasions for nine years. His reign provided stability to the western provinces during the Crisis of the Third Century, with effective administration and coinage.

After defeating the usurper Laelianus at Mainz, Postumus refused to allow his troops to sack the city. His soldiers mutinied and killed him, ending his reign. His death led to a period of instability in the Gallic Empire.

During Zeno's reign, the Western Roman Emperor Romulus Augustulus was deposed by Odoacer. Zeno recognized Odoacer as patrician but refused to recognize a new Western emperor, effectively accepting the end of the Western Roman Empire as a separate entity.

Zeno, who had been forced to flee Constantinople by the usurper Basiliscus, returned with an army of Isaurians and regained the throne. Basiliscus and his family were captured and executed, restoring Zeno's rule.

Emperor Zeno issued the Henotikon, an edict intended to reconcile the Chalcedonian and Miaphysite factions within the Christian church. The edict attempted to find a compromise but ultimately failed to heal the schism, alienating both sides and causing the Acacian Schism with the Papacy.

Zeno commissioned the Ostrogothic king Theodoric to invade Italy and overthrow the barbarian ruler Odoacer. This agreement removed a potential threat to the Eastern Empire and established Theodoric as the ruler of Italy, nominally as Zeno's viceroy.