If we talk about a famous wall built in Britain to block the passage of enemies, inevitably the Hadrian’s Wall will come to mind, erected in the 2nd century AD with the aim of defending against Pictish raids. Someone might also recall Antonine Wall, two decades later.

But there was a third wall – not Roman but medieval – that in 2010 was presented to UNESCO to be included in the World Heritage, although it did not succeed: the one known as Offa’s Dyke.

There are a few examples of this system of blocking outsiders if we look back at the past: the one built by Israel in the West Bank, the one made by Morocco in the Sahara, the famous Berlin Wall (which in this case was to prevent people from leaving), the Croatian walls of Ston, and the renowned Great Wall of China…

If most of the cited cases extend over vast territories (in addition to the 21,000 kilometers in China, the Moroccan wall covers another 2,720, for example), it would make more sense in Britain, where they were also favored by less rugged terrain. Thus, Hadrian’s Wall measured about 73 miles from the Solway Firth to the Tyne estuary, dividing the island into two halves. Antonine Wall, parallel to the former, reached 100 miles and left the limes already in Caledonia (Scotland).

But Offa’s Dyke had different characteristics. First, because adobe was used in its construction instead of stone. Second, because it was not built by the Romans but by the kingdom of Mercia, one of those that formed the Anglo-Saxon Heptarchy in the 8th century along with Essex, Northumbria, Wessex, Sussex, Kent, and East Anglia. And third, because instead of running from east to west, it ran from north to south, establishing the border between Mercia and the Welsh kingdom of Powys, which was not Anglo-Saxon but Briton, of Celtic origin.

It measured about 150 miles in length by 12.5 wide and 8 high, stretching from the Bay of Liverpool to the Severn estuary, with the Mercian domains to the east and the Welsh to the west. A convenient separation because, as the writer and traveler George Borrow records in his “Wild Wales” (an account of his journey through Wales in 1854 that includes folkloric, historical, as well as geographical aspects and was published in 1862):

It was customary for the English to cut off the ears of all the Welsh they found east of the dike, and for the Welsh to hang all the English they found west.

Powerful reasons to make the boundaries clear, no doubt, and in fact, the current border follows a similar trajectory. However, that demarcation was not by mutual agreement. The remains of the wall show that it had a ditch on the western side, indicating that it was built as a defensive system, presumably against Welsh incursions.

The name means Offa’s Wall, referring to the Mercian monarch who promoted its construction between 757 and 796 AD. He was an important figure not only for wearing the crown but also for introducing the penny as currency.

But, above all, for leading his kingdom to dominate most of southern England south of the River Humber, to the point that he was known as Rex Anglorum (King of the Angles), which was almost equivalent to saying of all the English; a remarkable feat considering that the unification of the country would not take place until the 10th century. He also maintained diplomatic relations with Charlemagne (they negotiated the marriage of their children, although without success).

Offa battled the Welsh in Hereford in the year 760 and undertook other campaigns against them in 778, 784, and 796. The limitations of testimonies make it difficult to know well his reign, but he must have been powerful enough to gather the necessary resources and labor required for the construction of the wall. In that sense, probably the workers, serfs, had to undergo mandatory and free labor, typical of feudalism, called corvée.

Now, one thing is for the wall to bear Offa’s name, and for him to be considered its author, and another is whether that is true. That was traditionally thought, but radiocarbon analyses conducted in 1999 on some soil samples suggest that it might be a work earlier than believed, at least in part, advancing the date considerably: to the year 446 AD. New analyses conducted in 2014 in other areas also gave very early results, between the years 541 and 651, with the oldest of all being from 430.

In fact, some researchers consider that the description that the Roman historian Eutropius left around the year 369 AD of the wall of Septimius Severus (which is not really a wall but reinforcements on Antonine Wall) in his work Breviarium Historiae Romanae would correspond to the original phase of Offa’s Dyke. Most archaeologists disagree because that would advance the dating even further (the Severan period was from 193 to 211).

It seems reasonable that when Bede the Venerable (who lived between the 7th and 8th centuries) talks about Severus’s Wall in his Ecclesiastical History of the English People, he is actually referring to Offa’s, as he says it was made of earth, not stone, topped by a wooden palisade, and with a ditch.

In any case, how to explain such an early chronology? There are two possibilities: one, that the Romans already built something there, and two, that the rest was probably the initiative of successive Mercian kings, not just Offa. This leads to questioning why the wall is attributed to that monarch.

Until now, historiographical sources were used to date it and explain its historical context. The main one is the Anglo-Saxon Chronicle, from the 10th century, which has the problem that there are several handwritten and discordant copies in some points.

But it was John Asser, a Welsh monk who lived in the second half of the 9th century and worked as a translator at the court of Alfred the Great of Wessex, who attributed the wall to Offa. Asser wrote one of the fundamental works for understanding the monarch’s reign, Life of King Alfred (which he later expanded with an annex on the history of England), and in it, he attributes the wall to Offa:

There was in Mercia, not so long ago, a vigorous king named Offa who terrified all the neighboring kings and provinces and who had a great wall built between Wales and Mercia from sea to sea.

Since the 1950s, historians like Cyril Fox and Frank Stenton began to question the veracity of those words. They admitted that the wall was “from sea to sea”, but not continuously, only where the topography did not constitute a natural defense itself, and doubted that the author was Offa. Others, like Frank Noble or David Hill, qualify those doubts by suggesting that the unbuilt areas may have been equipped with wooden palisades, a material that does not usually preserve.

However, Hill does not believe that Offa’s Dyke was from sea to sea but would be shorter, or it may constitute the main core of more wall sections built by other monarchs (Offa’s predecessor on the throne, Ethelbald, would have erected a section called Wat’s Wall), all connected to each other. Similarly, some, like John Davies, believe that the Welsh may have been consulted because the route seems to avoid certain corners, as if it were intended to cede those lands to the neighbor. It is difficult to know for sure, as being a dirt wall and not stone, the passage of centuries has eroded it so much that there is barely a trace.

Thus, some sections remain buried, and their excavation has been avoided for now to prevent deterioration. Others can be easily visited thanks to the so-called Offa’s Dyke Path, a tourist-cultural trail open to the public that was inaugurated in 1971 and is one of the longest in Britain, covering nearly 176 miles, from the aforementioned Severn estuary in Sedbury (near Chepstow) to Prestatyn on the north coast of Wales. There is also a visitor center in Knighton, where the most striking remains of the wall are located.

This article was first published on our Spanish Edition on December 7, 2018. Puedes leer la versión en español en Offa’s Dyke, la muralla medieval de tierra que separaba los reinos ingleses de los galeses


Keith Ray y Ian Bapty, Offa’s Dyke: Landscape and Hegemony in Eighth Century Britain | Erik Grigg, Warfare, Raiding and Defence in Early Medieval Britain | John Hunt, Warriors, Warlords and Saints: The Anglo-Saxon Kingdom of Mercia | Beda the Venerable, Ecclesiastical History of the English People | Michael Swanton, ed, The Anglo-Saxon Chronicle | Asser, Life of king Alfred the Great |Carlos de Miguel, Britania. Los siglos oscuros | VVAA, La transición del esclavismo al feudalismo | Mike Dunn, Offa’s Dyke Path | Wikipedia

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