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Roman Fort in Wales May Back Mabinogion Tale of Magnus Maximus's Camp
A newly identified Roman fort in Pembrokeshire, Wales, discovered in 2024 by Oxford specialist Dr Mark Merrony, may prove the medieval Mabinogion tale of emperor Magnus Maximus pitching his camp on Frenni Fawr was rooted in reality, with late fourth-century coins among the finds.
By Haut Monde Post
• October 12, 2026
• 3 Min Read
A Roman fort in Wales may hold the answer to one of the stranger questions in medieval literature: whether emperor Magnus Maximus really pitched his camp beneath a Pembrokeshire peak, as storytellers of the Mabinogion insisted. Fourth-century coins are among the finds at the newly identified site, which Dr Mark Merrony, a leading Roman specialist at the University of Oxford, discovered in 2024 and now leads in excavation.
The Legend of Macsen Wledig
Magnus Maximus was the Roman emperor who ruled Britain in the fourth century and led his troops against the Picts and Scots. A story about him is told in the Mabinogion, a collection of medieval epic tales of myth, magic and miracles.
In The Dream of Macsen Wledig, medieval storytellers described the emperor pitching his camp at Frenni Fawr, the 395-metre (1,300ft) easternmost peak of the Preseli Hills. Until now, there had been no archaeological evidence for a Roman marching camp or fort on or below the summit.
From Satellite Image to Dig
The site came to light about 2 miles (3.5km) south-west of Frenni Fawr's summit. Satellite imagery had shown a convincing outline in an overgrown field, and Merrony soon spotted a Roman tile, the first of many finds.
With financial support from Oxford University and crowdfunding, one of several planned excavations has just finished, confirming the site's theory and significance. The dig also produced an unexpected family moment:
- •Before excavation began, Merrony's brother Nick jokingly asked him to find coins.
- •Nick then found two coins dating from the late 4th century, to Merrony's surprise.
- •Merrony said it is fascinating to consider the two coins may be linked to the tale of Macsen Wledig, describing the Mabinogion as the Welsh equivalent of the Odyssey.
A Fortified Roman Presence
The fort measures 180 by 150 metres, sits on a slope with a commanding view, and likely held about 500 troops. Merrony described it as having a characteristic playing-card form, with rounded corners, and a perpendicular road.
Finds so far include:
- •an unusual iron stylus and many pottery shards
- •large quantities of Roman tiles
- •compacted clay floors and preserved wagon rut marks
A geophysical survey confirmed a rectangular building in the middle of the enclosure and a larger one immediately to the south, which Merrony said fits a headquarters building orientated east and thereby facing the enemy, and a commander's house.
The discovery overturns assumptions that the area's Indigenous Celtic tribe was on peaceful terms with the Roman invaders. It also builds on Merrony's earlier work: in 2022 he identified a Roman road along the southern shoulder of the Preselis, challenging assumptions that Romans did not venture far into Wales. His previous discoveries include two Roman villas, at Ford in Pembrokeshire and at Cutteslowe in Oxfordshire.
"If Magnus Maximus was there, there must have been an army there"
That is how Merrony framed the significance of the landscape, which he said holds the only Roman military site near where the Mabinogion places the emperor. He added that the heavily fortified Roman auxiliary fort may help unlock the mystery of a Mabinogion legend that has endured for nearly 1,700 years.
Merrony's research will appear in Antiqvvs, a quarterly magazine dedicated to archaeology, ancient art and history. Magnus Maximus will also feature in his forthcoming book, titled Lives of the Roman Emperors: From Augustus to Romulus Augustulus.
