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 modernBritish 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 riverRhine.

The specialists at the British Museum found no reason to doubt the authenticity of the coin, which resembled products minted at Rome during thesame period. But who was Silbannacus? And when did he reign?

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

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

Whatever the case, Silbannacus' coinage must have been of very short duration, and we may suppose that he reigned for no more than a few days atmost. But of his life and death we know nothing whatsoever. He was an insignificant figure in a turbulent age - so much so that history has forgottenhim entirely, and only two coins survive to bear witness to his very existence.

To read the complete article, see:
Silbannacus: the Roman emperor that timeforgot (www.historyextra.com/article/bbc-history-magazine/silbannacus-roman-emperor-time-forgot)