Medieval money mystery solved

Between 660 and 750 AD, Anglo-Saxon England witnessed a profound revival in trade involving a dramatic surge in the use of silver coins, breaking from a reliance on gold.

Around 7,000 of these silver ‘pennies’ have been recorded, a huge number, about as many as we have for the rest of the entire Anglo-Saxon period (5th century – 1066).

For decades, experts have agonised over where the silver in these coins came from.

Now a team of researchers from the Universities of Cambridge, Oxford and Vrije Universiteit Amsterdam have solved that mystery by analysing the make-up of coins held by the Fitzwilliam Museum in Cambridge.

The journal Antiquity published their study on 9th April 2024. Co-author, Professor Rory Naismith (Dept. of Anglo-Saxon, Norse & Celtic; Corpus Christi College), says:

“There has been speculation that the silver came from Melle in France, or from an unknown mine, or that it could have been melted down church silver. But there wasn't any hard evidence to tell us one way or the other, so we set out to find it.”

Previous research has tested coins and artefacts from the silver mine at Melle but Naismith and his colleagues turned their attention to less-studied coins which were minted in England, the Netherlands, Belgium and northern France.

Helpfully, Naismith had “a powerhouse of early mediaeval numismatic research” on his doorstep: The Fitzwilliam Museum.

To begin, 49 of the Fitzwilliam’s coins (dating from 660 to 820 AD) were taken to the laboratory of Dr Jason Day in Cambridge’s Dept. of Earth Sciences for trace element analysis.

Next, the coins were analysed by ‘portable laser ablation’ in which microscopic samples were collected onto Teflon filters for lead isotope analysis.

This is a new technique, pioneered by the Vrije Universiteit Amsterdam, which combines the minimally invasive sampling of laser with the high precision results of more traditional methods in which physical samples of silver are taken.

While the coins mostly contained silver, the proportion of gold, bismuth and other elements in them guided the researchers to the silver’s previously unknown origins. Different ratios of lead isotopes in the silver coins provided further clues.

The analysis revealed two major findings...

In the 29 coins tested from the earlier period (660 – 750 AD) – which were minted in England, Frisia and Francia – the researchers found a very clear chemical and isotopic signature matching 3^rd to early 7^th century silver from the Byzantine Empire in the eastern Mediterranean.

Image: Byzantine Emperor Constans II (641-668) or his son Constantine IV (668-685) depicted in the 7th-Century AD Mosaic of Imperial Privileges at the Baslica of Sant Apollinare in Classe, Italy

The silver was homogenous across the coins and characterised by high gold values (0.6 – 2%) and a consistent isotopic range, with no distinguishable regional variations among them.

No known European ore source matches the elemental and isotopic characteristics of these early silver coins. Nor is there any meaningful overlap with late Western Roman silver coins or other objects. These coins did not recycle late Roman silver.

“This was such an exciting discovery. I proposed Byzantine origins a decade ago but couldn’t prove it,” Naismith says.

The study’s lead author, Dr Jane Kershaw, from the University of Oxford, says:

“These coins are among the first signs of a resurgence in the northern European economy since the end of the Roman Empire. They show deep international trade connections between what is now France, the Netherlands and England.”

The researchers emphasise that this Byzantine silver must have entered Western Europe decades before it was melted down because the late 7th century was a low point in trade and diplomatic contacts.

“Elites in England and Francia were almost certainly sitting on this silver already,” says Naismith. “We have very famous examples of this, the silver bowls discovered at Sutton Hoo and the ornate silver objects in the Staffordshire Hoard.”

Together, Sutton Hoo’s Byzantine silver objects weigh just over 10kg. Had they been melted down they would have produced around 10,000 early pennies.

Kershaw says: “These beautiful prestige objects would only have been melted down when a king or lord urgently needed lots of cash. Something big would have been happening, a big social change.”

“This was quantitative easing, elites were liquidating resources and pouring more and more money into circulation. It would have had a big impact on people’s lives. There would have been more thinking about money and more activity with money involving a far larger portion of society than before.”

Naismith hopes to establish how and why so much silver moved from the Byzantine Empire into Western Europe. He suspects a mixture of trade, diplomatic payments and Anglo-Saxon mercenaries serving in the Byzantine army. The new findings also raise tantalising questions about how and where silver was stored and why its owners suddenly decided to turn it into coins.

The study’s second major finding revealed a later shift away from Byzantine silver to a new source.

The findings give new context to Charlemagne’s delicate diplomatic relations with King Offa of Mercia in England. Like Charlemagne, Offa took an active role in the silver trade and currency management. Both kings saw trade and politics as inseparable.

In a surviving letter sent to Offa in 796, Charlemagne discussed trade in commodities as well as political exiles. The pair also entered a trade embargo when a marriage negotiation turned sour.

“There was a lot of communication and tension between Charlemagne and Offa,” Naismith says. “Offa wasn’t in the same league, his kingdom was much smaller, he had less power over it, and he certainly didn’t have as much silver. But he remained one of Europe’s most powerful figures who was outside of Charlemagne's control.

“So they maintained a pretence of equality. Our findings add to a dynamic that England and France have had for a very long time.”

Naismith has no doubt that people in England would have been very aware that their silver was coming from Francia and that they depended on it.

“When commodities are only in certain places in limited quantities, questions of power and national interest will always come into play,” Naismith says.

“In the early Middle Ages, this transcended borders and rulers weren’t the only people involved. Merchants, churches and other wealthy people all had an interest. Rulers taking much more direct action was new for this period.”

Funding

This research was carried out under an ERC Starter Grant awarded to Jane Kershaw (Action number 802349) and an AHRC Leadership Fellowship (AH/S005498/1) awarded to Rory Naismith. JK's project title is 'Silver and the Origins of the Viking Age'. RN's project title is 'Foundations of Gold and Silver'.

Reference

J. Kershaw, R. Naismith, P. d’Imporzano and S. Merkel, ‘Byzantine plate and Frankish mines: the provenance of silver in north-west European coinage during the Long Eighth Century (c. 660–820)’, Antiquity (2024). DOI: 10.15184/aqy.2024.33

Find out more in this short film