Friday, December 9, 2022

Roman coins dismissed as fakes are genuine and depict ‘lost emperor’

Coins of an “emperor” Sponsian — long dismissed as forgeries — are genuine and reveal the existence of a forgotten military leader and breakaway Roman state in 3rd century Europe, a study claims.

Scientific analysis of the highly unusual coins, which were recorded as a new discovery in 1713, reveals markers of authenticity invisible to the human eye. A reconstruction of the career of Sponsian suggests that he ruled a breakaway regime in the province of Dacia — which lay mostly in today’s Romania — during the 260s and 270s AD and held the line against barbarian incursions at a critical juncture.

The earliest mention of the alleged discovery of the coins comes from a note by Carl Gustav Heraeus, Inspector of Medals for the Imperial Collection in Vienna. In March 1713, he recorded the acquisition of eight gold coins of five different designs that were said to have been unearthed in Transylvania. As many as 15 coins similar to those described by Heraeus are known from other collections and it appears that Heraeus chose a representative sample from a larger group that was dispersed on the market.

The coins differ significantly from official Roman coinage. All of the designs are crudely rendered and the coins are cast, rather than struck between dies as was the norm. The weight varies considerably and, at an average of 12.66g, they are more than twice as heavy as official Roman gold coins of the mid-3rd century. The coins were initially accepted as ancient but thought to be “barbarous” imitations produced beyond the frontiers of the empire. However, the more recent scholarly consensus has been that they were clumsy and eccentric 18th-century fakes.

As for the specifics of the designs, some are copies of coins of emperor Gordian III (238-244AD). Others are copies of coins dating from 47BC during the Roman Republic. A third type features an inscription dedicated to emperor Philip I or his son Philip II (244-249AD) beside a head of Roma — the personification of Rome — lifted from a 1st century BC silver coin of the Republic.

Finally, the coins naming “Sponsian” show his head, name and title of IMP[erator] on one side and an image copied from a 135BC coin of the Republic on the other, with the inscription C AVG. On the original, Republican, coin this abbreviation referred to the coin’s moneyer Caius Augurinus. However, if the Sponsian coins are genuine, 3rd century Romans may have interpreted the inscription as associating Sponsian with the imperial titles of Caesar and Augustus.

The four coins held at The Hunterian and analysed in the study. The coin depicting and naming Sponsian is top left. Photo: The Hunterian, University of Glasgow

The name Sponsian is highly unusual but known in one other instance, from a 1st century funerary inscription in Rome to a Nicodemus Sponsian. This inscription was excavated during the 1720s so could not have been known to any hypothetical forger working during the previous decade.

To investigate the coins’ authenticity, Dr Paul Pearson, of University College London, and colleagues at the University of Glasgow applied pioneering techniques to study four examples that are held at The Hunterian in Glasgow and now on public display. They used visible light microscopy, ultraviolet imaging, scanning electron microscopy, and reflection mode Fourier transform infra-red spectroscopy to study the four coins and, for comparison, two undoubtedly authentic Roman gold coins.

Researchers study the surface of the coin of Sponsian. Photo: The Hunterian, University of Glasgow

The analysis, published in the journal Plos One, revealed deep micro-abrasion patterns associated with coins that were in circulation for a long period of time. The researchers also studied tiny deposits of soil in the crevices of the coins, finding evidence that, after this extensive circulation, the coins were buried for a prolonged period before being uncovered. They said the collective evidence strongly suggested the coins were authentic.

Pearson, an earth scientist and author of The Roman Empire in Crisis, 248-260, explained: “We found scratches that are thousandths of a millimetre in length and less than that in diameter, just as you see on real coins. There was no evidence they’ve been scrubbed or artificially abraded and battered about to try to age them. What is more compelling is the dirt, which you can see cemented onto the surface. We thought this could have been baked on, glued on, rubbed on or painted on with some artificial substance. But it’s natural dirt and is cemented in place by silica. Very fine silica spots occur absolutely everywhere on these coins. Gold is unreactive, but provides a template for cement to crystallise onto the surface or cling in cracks and crevices. We compared that pattern to genuine coins and it’s exactly the same.

Soil deposits cemented into place by silica and scratches on the coin surface. Photo: The Hunterian, University of Glasgow

“I would go as far as to say that can’t be faked. At least, it would be very, very difficult to fake now and it would have been beyond anyone’s imagination during the 18th century.

“And the the thing that finally convinced me was that there’s a tiny layer of micron-scale crystal — so thousandths of a millimetre crystals of sulphate — on the surface of the dirt and that is a really common chemical reaction that occurs when things that have been buried get exposed to air. And all these deposits sit on top of the scratches. When we saw all this, we concluded that the coins were worn in antiquity, were buried for a long period and dug up.

“And that begs the question, who was Sponsian?”

Considering the historical record alongside the new evidence from the coins, the team suggest that Sponsian was an army commander in the province of Dacia during a period of profound turmoil in the 260s. Specifically, they suggest that Dacia became cut off from the imperial centre around 260 by incursions of Goths and other barbarians. They speculate that it seceded under its own military regime which first coined precious-metal bullion using old Republican-era designs, then using the names of the most recent previous emperors who had achieved success in the area — and finally under the name of a local commander, Sponsian. The Republican imagery may have been used due to an association of the venerable coins with high-purity bullion.

They said their scenario may explain an apparent contradiction in Roman sources that has long puzzled historians. These state, on the one hand, that Dacia was lost to the empire during the reign of Gallienus (260-268), but also that it was Aurelian (270-275) who evacuated the people and soldiers to a new province south of the Danube. Confusingly this was also named Dacia (Auerliana) for propaganda purposes.

Both statements could be reconciled if the original province was cut off and seceded under Gallienus, and later evacuated in an orderly fashion when Aurelian — a far more effective commander than Gallienus — secured withdrawal routes. According to Pearson, it is possible that Sponsian cooperated with the Aurelian regime and went into retirement, but more likely that he was murdered or executed.

The team believe the coins were produced from the precious metals that were abundant in Dacia’s mines and had previously been exported to Rome. The coins would have been used to pay senior soldiers and officials in gold and silver by weight after official coin supplies were cut off. The only imperial mint in Dacia had closed in the mid-250s but specialists could have been coopted from the local jewellery industry which worked in gold using clay moulds.

“We think it’s fair to call him a Roman emperor”

Dr Paul Pearson

The breakaway state in Dacia would have existed in a period of numerous revolts and usurpers and at the same time as the secessionist Gallic Empire in western provinces including Britain, Gaul and Germany. If it lasted into the early 270s, it would also have been contemporaneous with the breakaway Palmyrene Empire in several eastern provinces.

In their paper, the researchers argue that, under their scenario, Sponsian should not be seen as a usurper challenging central authority. Rather, he acted out of local necessity to protect the population when secure communication with Rome was impossible. Pearson said: “We think it’s fair to call him a Roman emperor, because his name is Roman, he commanded Roman legions — that’s what the title [imperator] says — and he styled himself as an emperor, albeit of a local variety.”

He added that, in holding the frontier, Sponsian may have played an important role in prolonging the empire’s survival. “The Gothic Confederation was very strong to the east. They controlled all the lands from the Baltic down through to the Black Sea, across the neck of Europe. So Sponsian might have been a bulwark against further incursions. The legions there not only had the manpower, but also weapons factories and mines where they could mine iron. So they had the whole operation to keep themselves going as a military state. So it may be that they prevented further incursions by the Gothic Confederation and saved the empire.”

The top image shows the coin of Sponsian analysed in the Plos One study. Photo: The Hunterian, University of Glasgow.

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