In 1937, the British Museum acquired a mysterious Roman coin from a Swiss coin dealer. Made of debased silver, and about the size of a modern British 10 pence, it bore the name and portrait of an emperor completely unknown to history. The portrait on the mystery coin showed a young man, and the inscription around his head read IMP MAR SILBANNACVS AVG, or ‘Emperor Mar(cius?) Silbannacus Augustus’. According to the Swiss dealer, the coin had been found in Lorraine, the north-eastern region of France close to the river Rhine. 

 

The emperor’s name was as mysterious as his coin. No historical source, document or inscription mentions an emperor, or even a usurper, with a name resembling Silbannacus. Even the name itself is unusual – it is perhaps a misspelling of Silvannacus or Silvaniacus, which might possibly indicate northern Italian origins. Furthermore, nobody is sure what the abbreviated name MAR stands for: maybe a Roman family name such as Marius or Marcius. Yet there are no references in the historical sources to any usurper or prominent military personality of the mid-third century called Marius, Marcius, Silvannacus or Silvaniacus. 

 

Nor did the reverse of the coin provide any pointers. There were no obvious parallels among the coins of other mid-third century emperors with which to compare the design on the unique coin of Silbannacus. Instead, the design depicted a figure of the god Mercury, a deity found only infrequently on Roman imperial coins before the later third century AD. 

 

The only clues to Silbannacus’s mysterious coin lay in the place where it was said to have been found and the type of coin it was. The coin was of a kind current in the middle of the third century AD (between around 238 and 260), a period for which there are few reliable historical accounts. This was a time of political turmoil in the Roman empire – a violent age of barbarian invasions and civil wars, as rival army commanders fought for supreme power.

 

So it was suggested that Silbannacus could have been a usurper, perhaps someone who had gained control of the Roman armies on the Rhine, and managed to produce a few coins in the region before some catastrophe overtook him. A rough date was proposed – the reign of the emperor Philip, who ruled from AD 244 to 249. During this period there had been numerous usurpers, some of whom minted coins. The enigmatic Silbannacus was therefore suspected to be one of several unsuccessful usurpers during Philip’s reign. It was an educated guess, but no more.

 

For several decades the British Museum coin was the only known example of currency minted by Silbannacus. Then another coin was found somewhere in the vicinity of Paris, where it entered a private collection. The existence of this second coin was not generally known until 1996, when it was published by a French specialist. It had a different design on the reverse, showing the god Mars. This design copied one used by another emperor of the period, called Aemilian, who reigned for a mere three months in AD 253. On the basis of this evidence, it seemed likely that Silbannacus should be dated slightly later than the time of Philip. Was it possible that Silbannacus was a usurper in AD 253, at the time of the short-lived emperor Aemilian?

 

The year AD 253 is a particularly obscure one in Roman history, because there are very few reliable sources that cover it. At the beginning of this year, the legitimate emperor was Trebonianus Gallus, who had reigned since AD 251. Aemilian was then a commander in control of Roman armies on the Danube, and in the summer of AD 253 his soldiers won a victory over the Gothic barbarians in the area. In jubilation, the troops proclaimed their commander emperor. When he heard of this, Trebonianus Gallus ordered another provincial army commander, Valerian, to march against the usurping Aemilian. But it was too late – Aemilian quickly invaded Italy and Trebonianus Gallus was overthrown. 

 

The victorious Aemilian reached Rome and became the legitimate emperor of the Roman world. On the coinage, his portrait replaced that of Trebonianus Gallus. Yet within weeks of gaining supreme power Aemilian faced a rebellion. Valerian’s armies, having failed to act in support of Trebonianus Gallus, now proclaimed their commander emperor. Aemilian left Rome to confront Valerian but was assassinated by his own soldiers.

 

It is possible that Silbannacus belongs to this murky episode in Roman history. Specialists have noted that the style of his coin is very similar to those minted at Rome. It may be the case that Silbannacus’ coinage was indeed minted in the capital, and that he briefly gained control there during the period of conflict between Aemilian and Valerian. Perhaps he was one of Aemilian’s officers who, after Aemilian’s murder, tried to secure the city of Rome against Valerian. If he did, he was unsuccessful: Valerian swiftly gained control of the capital and became the legitimate emperor.

 

Whatever the case, Silbannacus’ coinage must have been of very short duration. Of his life and death we know nothing whatsoever. He was an insignificant figure in a turbulent age – so much so that history has forgotten him entirely, and only two coins survive to bear witness to his very existence.