Postumus

Postumus
Emperor of the Gallic Empire
Coin featuring Postumus.
Reign	260–269
Predecessor	Gallienus (as ruler of the united Roman Empire)
Successor	Marcus Aurelius Marius
Born	Gaul
Died	269 Mogontiacum
Issue	Postumus Junior (doubtful)
Full name Marcus Cassianius Latinius Postumus (prior to accession); Imperator Caesar Marcus Cassianius Latinius Postumus Pius Felix Augustus Germanicus Maximus (as emperor)

Marcus Cassianius Latinius Postumus was a Roman commander of provincial origin who ruled as emperor in the west. The Roman army in Gaul threw off its allegiance to Gallienus around the year 260, and Postumus assumed the title and powers of emperor in the provinces of Gaul, Germania, Britannia and Hispania, thereby founding what scholars have dubbed the Gallic Empire. He ruled for the better part of ten years before he was murdered by his own troops.

Little is known about the early life of Postumus. He has been claimed as a Batavian; certainly his coinage honours deities—Hercules Magusanus and Hercules Deusoniensis—who would have been popular among the Batavians. Hercules Magusanus was probably an interpretatio romana translation of the Germanic deity Donar.Deusoniensis may refer to the town of Deuso, located in or near Batavian territory and likely to be identified with Diessen; it has been hypothesized that Postumus himself was born in Deuso. From these relatively obscure provincial origins, Postumus would have risen through the ranks of the army until he held command of the Roman forces "among the Celts". What his precise title was is not definitely known, though he may plausibly have been promoted by the emperor Valerian to the position of imperial legate of Lower Germany. Postumus was evidently in favour at court, and, according to König, was granted an honorary consulship.

By 259, Valerian was campaigning in the east against the Persians, while his son and co-emperor Gallienus was preoccupied with the situation on the Danubian frontier. Consequently, Gallienus left his son, Saloninus, and military commanders, including Postumus, to protect the Rhine. Amid the chaos of an invasion by the Alamanni and Franks, and spurred on by news of the defeat and capture of Valerian, the army in Gaul revolted and proclaimed Postumus emperor.