In the second half of the 7th Century Mercia was subject to Northumbria. Mercia was originally a pagan country, converting to Christianity in 656. Saint Chad moved the Bishopric to Lichfield in 669. It is believed that Saint Chad baptised converts from the Hanmer area in the lake at Bettisfield (which has since been drained). Mercia finally gained independence from Northumbria after the battle of Trent in 679, and took control of Pengwern sometime around 700, noted with lament in the annals of Powys. It may be assumed that Saxon settlers started to move into our local area from about 700 onwards, but if they did drive out the Celts then Powys must have recolonised this area in later Saxon times.
The 8th century saw Mercia rise to great power under two of its kings – Aethelbald (716-757) and Offa (757-796). It is thought that Chester became part of Mercia during Aethalbald’s reign. Offa is credited with building Offa’s Dyke. The central section of Offa’s dyke was very strong and probably had a wooden palisade, indicating its intension as a defensive barrier against a strong kingdom of Powys. By contrast the northern section was much lower and not palisaded, indicating more of a political boundary than a defensive work. It shows that Gwynedd was the weaker kingdom in this period. The line of the dyke should not be confused with the public footpath called ‘Offa’s dyke’. The actual dyke is Wrexham side of the Clwyd Hills, whereas the footpath goes over the top.
Wat’s dyke runs from the old Oswestry hill fort to the north coast, typically 2 miles east of Offa’s dyke. It runs underneath the Wrexham General Station. Nothing is known of Wat, and whether he is the same person that gave his name to Watling Street. Historians have always presumed that it is earlier than Offa’s Dyke, but there is no convincing archaeological evidence of this. What may be surmised is that it was built at a time when Gwynedd was a strong power.
Although the Saxon economy was largely rural, they did recognise the importance of minting coins. Mercia had a series of short lived kings in the first half of the 9th Century, and increasingly came under the power of Wessex. Mercia led a campaign into north Wales, capturing Deganwy castle in 821 – the capital of Gwynedd, near to Colwyn Bay. A further joint campaign with Wessex in 852 led to the subjugation of north Wales.