National Trail Offa’s Dyke website – History text May 2006 (Ian Bapty, CPAT)
What is the Offa's Dyke ancient monument?
Offa's Dyke is an amazing 1200 year old linear bank and ditch running through the English/Welsh borders from Treuddyn ( near Wrexham in north east Wales) to Sedbury Cliffs (on the Severn estuary, in southern Gloucestershire).
The Dyke consists of an earthen bank which can be up to 25 feet high, associated with a ditch to the west, and often occupies what seems like a deliberately imposing position in the landscape, typically presenting fine and commanding views into Wales. It is not known exactly what the Dyke looked like when first built, but archaeological excavation suggests the western side of the bank was revetted with turf to create a near vertical face, and it is possible that some kind of palisade or wall also existed on top of the earthwork.
Bishop Asser, writing about a century after the presumed date of Offa’s Dyke’s construction, famously describes it as running ‘from sea to sea’. Archaeological research has not confirmed this assertion, and there are major apparent gaps in Herefordshire and elsewhere, with 80 miles of the earthwork surviving today (most of which is followed by the Offa’s Dyke Path). Offa’s Dyke is the biggest and most impressive of several such ‘Dyke’ systems in the Welsh borders, notably including the similar Wat’s Dyke which runs for 40 miles through the northern Marches a few miles to the east of Offa’s Dyke.
Offa’s Dyke is Britain's longest ancient monument. It is the most dramatic built structure to survive from Anglo-Saxon times, and as such is an important reminder of a key phase in British history which has left relatively few substantial visible remains. Indeed, not only was the Dyke without equal in its own era, no constructional undertaking of similar landscape scale was to be built in Britain for another 1000 years until the great canal schemes of the 18th century.
Even today, visitors to the Dyke are immediately struck by the sheer size of the undertaking. First of all there is the simple scale of the earthwork and a sense of the immense effort of building the massive bank and digging the ditch with only hand tools. Then there is an appreciation of the engineering and planning skill with which the Dyke fits into the landscape whether skirting the Wye Valley in Gloucestershire, exploiting the contours, ridges and slopes of the Clun area in Shropshire, or marching boldly across the lowlands east of Montgomery. And finally, you get to thinking about the organisation and logistics behind a construction project like this, and the political control and sophisticated administrative systems which must have underlain it. And all this from a time which used to be referred to as the ‘Dark Ages’!’
Offa and the history of the Dyke
The ‘Offa’ of Offa’s Dyke was King of the Anglo-Saxon Kingdom of Mercia from 757-796. Mercia, centred on what is today the English Midlands, was one of a number of independent kingdoms which had emerged in the mid/later first millennium AD from the gradual extension of Anglo-Saxon political control over much of former Roman Britain. Offa established, through military campaigns and political alliance, Mercian control over much of what we now call England and indeed saw fit to describe himself as ‘Rex Anglorum’ (‘King of the English’). Although very little direct historical documentation relating to Offa has survived, we can still glimpse a powerful leader and astute politician who was treated as an equal by Charlemagne, the greatest European ruler of the age.
Offa’s Dyke itself is the best evidence we have of the power and achievement of Offa. The usual suggestion is to see the building of the Dyke as an attempt to rationalise a western boundary between Mercia and the independent British (Welsh) Kingdoms then present in modern Wales, who Offa had fought against with only partial success in a number of military campaigns. Cyril Fox, an archaeologist who made a pioneering study of the earthwork in the 1920s and 1930s, interpreted the Dyke as the product of a negotiated agreement between Mercia and the Welsh Kingdoms. That view has been disputed by more recent researchers such as Frank Noble and David Hill, who explain the Dyke more as a directly defensive earthwork built explicitly in the Mercian interest at a time of continuing instability along the presumed frontier.
It may indeed be that part of the purpose of the Dyke was simply its extraordinary physical presence in the landscape and the demonstration of Mercian power that went with the ability to plan, design and construct it. It is even possible that the Dyke was meant to explicitly emulate the kind of engineering achievement represented by Hadrian’s Wall and other long defunct Roman monuments (whose remains must have been known to 8th century Anglo-Saxons), so promoting Offa as some kind of successor to that tradition and the political control that had gone with the Roman capacity to create such impressive state infrastructure.
The historical understanding of the Dyke has resonances beyond the immediate context of Offa. The Dyke uniquely exemplifies processes of increasingly political centralisation in Anglo-Saxon Britain and contemporary Europe which were eventually to lead to the emergence of the geographical and cultural domains - such as England and Wales - we still live within. It may be that the Dyke had, in particular, a direct influence on the realisation of a politically coherent Welsh identity. Though short lived as an active Mercian/English frontier, its existence as a dividing line in the landscape may still have been a powerful ideological statement of the apparent separation of all to the west from ‘English’ Britain, and so helped to create a common sense of unity among Welsh peoples which had not previously existed.