To the layman it’s a muddy ditch but the dug-out sections at Chirk Castle are helping archaeologists piece together the history of a king’s legacy. Jamie Bowman digs further...

BUILT at the command of the eighth-century king of Mercia, Offa’s Dyke is today Britain’s longest ancient monument, following the border for 177 miles between England and Wales.

Video by Rick Matthews

Yet despite years of study, the origins of the Dyke, which extends from the shores of the Dee estuary in the north to Severn Estuary near Chepstow in the south, is still shrouded in mystery and conjecture.

Now a new archaeological dig at Chirk Castle near Wrexham is hoping to shed some more light on the earthwork which runs straight through the castle's grounds and beyond.

"This is all part of a joint-funded project by Cadwr and the National Trust called the Linear Earthworks Project," explains senior archaeologist for Clwyd Powys Archaeology Trust Ian Grant, as we stand on the edge of a trench in the shadow of Chirk Castle.

"Two of the most prominent earthworks we have in this country are Offah's Dyke here and Wat's Dyke which runs through Erdigg in Wrexham and predates Offa's so it was clear there was an opportunity to investigate the origins of both."

Offa, who ruled the Kingdom of Mercia, which covered most of the Midlands from 757 until his death in July 796, is considered one of the more remarkable kings to have ruled much of Anglo-Saxon England.

Driven by a lust for power, he was frequently in conflict with the various Welsh kingdoms with evidence of a battle between the Mercians and the Welsh at Hereford in 760, and other campaigns against the Welsh in 778, 784 and 796.

"It's been the long-held belief that the Dyke was started by King Offa as a frontier barrier facing Wales," says Ian. "Whether it was a defensive barrier or whether it had another purpose such as the control of trade and people, we just don't know.

"It's also believed that it may have been started by an earlier king and it is in fact a 'work in progress' over 200-300 years because if you look at the scale of the Dyke it is a phenomenal undertaking and not something you are going to construct over a decade."

This belief that Offa's Dyke may have been started by an earlier king has proved the main inspiration for Ian's research with the archaeologist and his team unearthing deposits of material such as charcoal which can be sent off for radio-carbon dating.

"We are wondering if it was started earlier and King Offa has then put his power behind it as well as it then being maintained after him," explains Ian.

"We are looking for what remains of the Dyke and predominantly the ditch which ran alongside. If you can get to the bottom of the ditch you can find the materials that were used to create the earthwork which was a big obstacle.

"The ditch could have been anything from five to six metres wide and three metres deep so if you wanted to move something like cattle from one kingdom to the next you are going to need selected points where you could drive them through.

"Burnt charcoal material from the bottom of the ditch alongside things like seeds and grains is what we're really looking for -the stuff left by the work parties building the dyke cooking with fires and leaving their detritus.

"In order to date the Dyke you don't necessarily need all of the Dyke itself - you just need the earliest parts which you can extract. send to the labs where they can do carbon dating which is usually accurate to around 100 years."

At an earlier excavation at Plas Offa near Chirk, one radiocarbon date from turf redeposited within its bank suggested a possible origin as early as the fifth century AD, while a few metres away another sample from the base of the bank indicated a possible ninth-century date.

"That's a period of over 300 years of constant construction and maintenance," says Ian. "Those earlier dates are the ones which really interest us because they suggest we need to do more work and research.

"If we keep getting dates back as early as that it all adds to the suggestion that Offa's Dyke has much earlier origins. We've joked that Offa has basically got a better public relations team who've put his name to it."

Offa himself was a Christian king who many historians regard as the most powerful Anglo-Saxon king before Alfred the Great with his reign also sometimes viewed as part of a process leading to a unified England.

"Offa was around at a time which saw a great expansion of the Kingdom of Mercia," continues Ian. "He wanted the kingdom to be recognised as the predominant force in Anglo-Saxon England

"Emperor Charlemagne was around at the same time in Europe and Offa wanted to emulate him and be seen to be on a similar level."

The dig itself has seen around 20 volunteers working on two sections of the Dyke within the castle grounds, with one by the castle's man-made lake and the second on an area right in front of the castle, but it hasn't all been plain sailing.

"Hurricane Ali and Hurricane Bronagh both claimed a tent between them and we lost two gazebos," laughs Ian. "I didn't think toilets could fly but one of them is now in the land of Oz I think.

"The dig up at the castle saw us check in the lawn area whether there was any evidence of archaeological remains and we found enough to suggest it's worth doing further excavations.

"We found a lot of stone rubble which suggests some structures dating to the Tudor period and we found a lot of pottery dating back to medieval times.

"We also found flints dating back to around 8,000 years ago which shows there has always been occupation here since pretty much the dawn of time."

After a few weeks digging, Ian and his team are preparing to move on but he is confident that their various finds and discoveries from different time periods mean they could well be back for further exploration.

"If you look at the castle it's on a raised area and when you stand there and see the views back across to the border you realise it's quite a commanding position," he adds.

"It's at the head of two valleys with a good water source and is very lush and you would expect Bronze Age activity here as well as burials.

"There's no doubt it's a special spot and people throughout the ages will always congregate to a place with value like this,"