Postumus

• 1. Introduction

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  Postumus, a Roman commander of Batavian origin, seized power at one of the most chaotic moments the Roman Empire had ever faced, and then held on to it for nearly a decade. In the year 260, the reigning emperor Valerian had just been captured by the Persians. The frontier on the Danube was in crisis. Germanic tribes were pouring across the Rhine. Into that vacuum stepped a provincial military man whose full name was Marcus Cassianius Latinius Postumus, and whose empire would, at its height, encompass Gaul, Germania, Britannia, and Hispania. He never marched on Rome. He set up a senate, a praetorian guard, and a consulship. He minted coins of better quality than those issued by the legitimate emperor. The questions that linger around Postumus are fascinating. Was he a breakaway ruler who wanted independence, or a loyal defender playing a desperate hand? How did a soldier from the obscure Batavian borderlands hold a rival empire together through wars, rebellions, and financial collapse? And why did his own troops finally turn on him over a city he refused to let them loot?

• 2. The Batavian Soldier

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  Postumus honored two versions of Hercules on his coins: Hercules Magusanus and Hercules Deusoniensis, deities that would have been popular among the Batavians, a people living in the Rhine delta. Hercules Magusanus was probably an interpretatio romana, a Roman-language rendering, of the Germanic deity Þunraz. Deusoniensis likely refers to a place called Deuso, a town in or near Batavian territory that scholars have suggested may be the modern-day Diessen. Some historians have proposed that Postumus was himself born in Deuso, though this remains a hypothesis rather than a certainty. His early life is otherwise almost entirely unknown. What the sources do suggest is that he climbed the military hierarchy from provincial obscurity until he held command of Roman forces described as being "among the Celts." His precise title at that point is not definitively established, but he may have been promoted by Emperor Valerian to the position of imperial legate of Germania Inferior. He was evidently well regarded at court; according to König, he was also granted an honorary consulship.

• 3. The Seizure of Power

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  By 259, Valerian was fighting in the east against the Persians, and his son and co-emperor Gallienus was tied down on the Danubian frontier. Gallienus left his own son, Saloninus, along with Postumus and other commanders, to guard the Rhine. The situation quickly deteriorated. Alamanni and Frankish raids struck Gaul, and then came the shattering news that Valerian had been defeated and captured. In 260, Postumus and a general named Marcus Simplicinius Genialis crushed a Juthungian army that was returning from Italy loaded with Roman prisoners and plunder. The Juthungi had already been turned back by Gallienus at Mediolanum, the city known today as Milan, but the booty they carried had not been recovered. Postumus distributed those recovered spoils to his legions. Saloninus, guided by his praetorian prefect Silvanus, demanded that the captured wealth be sent to his residence at Colonia Claudia Ara Agrippinensium, the city now known as Cologne. Postumus staged a performance of reluctant compliance, effectively inviting his troops to mutiny. They did. They proclaimed Postumus emperor, then besieged Cologne, trapping Saloninus and Silvanus inside. After the city walls were breached, both were killed, though Postumus's supporters later attributed the murders to local Gauls rather than to the new emperor himself.

• 4. Building the Gallic Empire

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  Recognition came quickly. Gaul, Germania Superior, Germania Inferior, and Raetia acknowledged Postumus almost immediately after the coup in 260. By 261, Britannia, the province of Gallia Narbonensis, and Hispania had also accepted his authority, possibly following a military expedition to Britain during the winter of 260-261. Postumus established his capital in northern Gaul, probably at Cologne or at Augusta Treverorum, the city now called Trier. He assembled a government that consciously mirrored traditional Roman structures. He took the office of consul alongside a colleague named Honoratianus. He became pontifex maximus and held tribunician power annually, exactly as Roman emperors had done before him. He is thought to have created a senate, possibly modeled on the Council of the Three Gauls, and a praetorian guard; one of that guard's officers was a man named Victorinus, who would later become a Gallic emperor in his own right. The senior figures of his administration, including Victorinus and a man named Tetricus, came from his power base in northern Gaul, and the whole apparatus rapidly took on a Gallic character. Prior to the 10th of December 261, Postumus also adopted the title Germanicus maximus, which he earned by successfully defending Gaul against German incursions. His coins declared him Restitutor Galliarum, the restorer of Gaul, and Salus Provinciarum, the bringer of security to the provinces.

• 5. The Coin That Measured an Empire

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  Postumus's coins were, by any measure, better than those of Gallienus. They were of superior workmanship and carried a higher precious metal content, which in an era when currency debasement signaled imperial weakness, was a pointed statement about who was actually governing well. His control of the silver and gold mining regions in Spain and Britain gave him a material advantage. He also benefited from employing master minters who had originally come into Gaul with Gallienus. After his victories against the Franks and Alemanni in 262 and 263, the coin types shifted to peaceful imagery. Felicitas Augusti, a motif celebrating imperial happiness, dominated the coinage for some time after 263. Then, in 268, he issued a celebrated gold coin series known as the Labours of Hercules, honoring the deity he regarded as his divine patron. Shortly after that same year, the coinage was suddenly debased, a sign that serious financial problems had arrived. Scholars attribute the debasement to a possible disruption in silver production from the Spanish mines, or to the mounting cost of keeping an increasingly restless army in line. Some aureus coins from his reign carry an unusual triple portrait that may depict his wife and two sons, although this identification remains a matter of scholarly discussion.

• 6. Gallienus Strikes Back

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  For four years after 260, Gallienus was too occupied with Germanic incursions and rival claimants in the eastern part of the empire to move against Postumus in any sustained way. In 265, he finally launched a campaign. His first attempt failed, not because of any particular brilliance on Postumus's part, but because of a lapse by Gallienus's own cavalry commander, a general named Aureolus. Postumus escaped what should have been a trap, and Aureolus was demoted for the failure. That demotion had consequences: Aureolus eventually turned against Gallienus in 267. A second campaign, led by Gallienus himself, appeared to be going well until Gallienus was wounded while besieging a city in Gaul, possibly Augusta Treverorum. He was forced to withdraw. By the end of 265, Postumus's coins were already celebrating triumph over Gallienus, and the festivities marking his quinquennalia, the five-year anniversary of his reign, continued into 266. Gallienus, caught up in crisis after crisis across his fractured empire, never launched a third campaign. The year 266 also saw Postumus take the consulship for the fourth time, with Marcus Piavonius Victorinus as his colleague, a Gallic noble and senior military officer whose selection to that high post appears designed to widen Postumus's political base.

• 7. A Golden Opportunity Lost

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  In 268, Aureolus, who commanded Mediolanum in Gallienus's name, rebelled. He declared for Postumus. Mediolanum, along with its north Italian and Raetian hinterland, would have been a critical strategic asset for any march on Rome. Postumus did not move. For reasons that the sources do not make fully clear, he failed to support Aureolus. Gallienus defeated and then besieged Aureolus inside the very city where he had once turned back the Juthungi. Before the summer of 268 was over, Gallienus was assassinated. His successor, Claudius II, captured and killed Aureolus, closing the window that Postumus had let pass. The army in Gaul had expected their emperor to act, and his inaction compounded the grievance of the coinage debasement already underway. The sequence of events that would end Postumus's reign had begun.

• 8. Fall and Legacy

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  Postumus assumed his fifth consulship on the 1st of January 269. Within weeks, one of his own top military leaders, Laelianus, the governor of Germania Superior, was declared emperor in Mogontiacum, the city now known as Mainz, by the local garrison and the troops of Legio XXII Primigenia. Postumus marched, captured Mogontiacum, and killed Laelianus within a few months. His army then demanded the right to sack the city. When Postumus refused, they killed him. The mutineers elevated a common soldier named Marius as the next emperor. Marius lasted only a brief time before being overthrown by Victorinus, the man who had served as Postumus's consul and as an officer of his praetorian guard. In the chaos, the Gallic Empire lost Hispania. Postumus's coinage survived him in reputation. Numismatists have long been drawn to it for its quality and relative abundance. The Labours of Hercules gold series remains particularly well regarded, as do several aurei that show Postumus in full-face portrait rather than the standard profile, an unusual and striking choice for an emperor who insisted, in almost every other way, on looking exactly like the rulers he replaced. Most of what is known about Postumus comes from ancient sources thought to derive from the Enmannsche Kaisergeschichte, including the works of Aurelius Victor, Eutropius, and the Historia Augusta, where Postumus appears among the Thirty Tyrants.