After the Roman occupation of Britain in AD410, there comes a period in British history often referred to by historians as the 'Dark Ages'. This is a timeline that stretches for almost one thousand years, ending with the 'English renaissance period', c1520. The main reason why this term became popular is simply due to the lack of archaeological evidence available to us. Written records are extremely scarce and, as buildings were predominantly constructed of timber, any structures have long since rotted away.

Unfortunately, the use of the word 'dark' has led to implications that society must have collapsed when the Romans left, and that our ancestors must have reverted back to some form of tribal savagery. However, one substantial monument survives from the Anglo-Saxon period that goes a long way to dispelling this, and that is the incredible feature called 'Offa's Dyke'.

From AD757 to AD796, Offa was ruler over the Anglo-Saxon Kingdom of Mercia (an area equivalent to the combined West and East Midlands of England today). Mercia was just one of several independent Kingdoms in England at the time but, through military campaign and clever political alliance, Offa was to become one of England's most powerful rulers.

Offa's Dyke is a linear earthwork, comprising a ditch and rampart, which roughly follows the modern boundary between England and Wales and covers a distance of some 177 miles. Work commenced c785, and must have been a massive undertaking, clearly demonstrating the power that King Offa commanded. Not only must it have required a huge amount of manpower equipped with very basic tools, but there were also the planning, engineering, logistical and organisational skills to be considered.

As mentioned, Offa's Dyke comprises a ditch to the west, and a rampart, constructed from the ditch spoil to the east. The rampart may have been topped in whole, or in part, by a wooden palisade, but there is no firm evidence for this. Once completed, Offa's Dyke is estimated to have been approximately 89ft (27m) wide and 26ft high (8m) from the bottom of the ditch to the top of the rampart.

Over time, much speculation has arisen regarding the actual purpose of Offa's Dyke. It appears to have been constructed in response to events involving the Princes of Powys, but whether it was intended as a mutually agreed boundary, a defensive structure during unstable times, or some other purpose, will never be known. Disagreement has also been voiced as to whether King Offa was responsible for construction of the entire length of the Dyke. Asser, the biographer of King Alfred, gave the first known reference to it some 100 years later when he wrote:

"there was in Mercia in fairly recent time a certain vigorous king called Offa, who terrified all the neighboring kings and provinces around him, and who had a great dyke built between Wales and Mercia from sea to sea".

However, the current understanding is that Offa was definitely responsible for the central part of the dyke, but it is believed now that the coastal sections may have been constructed at a later date. Today, this impressive relic of Anglo-Saxon England is enjoyed by many thousands of people who choose to walk the Offa's Dyke Trail. For those preferring a less arduous encounter, well preserved sections can be found near to the town of Knighton, which is also home to the Offa's Dyke Centre.