England–Wales border

The England–Wales border, sometimes referred to as the Wales–England border or the Anglo-Welsh border, runs for 160 miles (260 km) from the Dee estuary, in the north, to the Severn estuary in the south, separating England and Wales.

It has followed broadly the same line since the 8th century, and in part that of Offa's Dyke; the modern boundary was fixed in 1536, when the former marcher lordships which occupied the border area were abolished and new county boundaries were created. The administrative boundary of Wales was confirmed in the Local Government Act 1972. Whether Monmouthshire was part of Wales, or an English county treated for most purposes as though it were Welsh, was also settled by the 1972 Act, which included it in Wales.

The modern boundary between Wales and England runs from the salt marshes of the Dee estuary adjoining the Wirral Peninsula, across reclaimed land to the River Dee at Saltney just west of Chester. It then loops south to include within England an area southwest of Chester, before rejoining the Dee, and then loops east of the river to include within Wales a large area known as Maelor Saesneg ('English Maelor'), formerly an exclave of Flintshire, between Bangor-on-Dee (in Wales) and Whitchurch, Shropshire (in England). Returning to the River Dee as far as Chirk, the boundary then loops to the west, following Offa's Dyke itself for about 2 miles (3 km), and including within England the town of Oswestry, before reaching the River Vyrnwy at Llanymynech. It follows the Vyrnwy to its confluence with the River Severn, and then continues southwards, rising over Long Mountain east of Welshpool. East of Montgomery, the boundary again follows the line of Offa's Dyke for about 2 miles (3 km), before looping eastwards to include within Wales a large area near Churchstoke including Corndon Hill. It then runs westwards to the River Teme, and follows the river southeastwards through Knighton before turning south towards the River Lugg at Presteigne, which is within Wales.^{[citation needed]} The boundary continues southwards across hills to the River Wye, and follows the river upstream for a short distance to Hay-on-Wye, on the Welsh side of the border. It continues southwards and rises through and across the Black Mountains, following the Hatterall Ridge past Llanthony on the Welsh side and Longtown, Herefordshire on the English side, to reach the River Monnow near Pandy. It then generally follows the river, past Pontrilas (in England) and Skenfrith (in Wales), towards Monmouth, looping eastwards to include the town itself and a surrounding area within Wales. At Redbrook, the boundary again reaches the Wye, and follows the river southwards, past Tintern and Chepstow on the Welsh side, to its confluence with the Severn at the Severn Bridge. The boundary then continues down the Severn estuary towards the Bristol Channel, with the small island of Flat Holm being administered as part of Wales and the neighbouring island of Steep Holm as part of England.^{[citation needed]}

The boundary passes between Flintshire, Wrexham County Borough, Powys and Monmouthshire in Wales, and Cheshire, Shropshire, Herefordshire and Gloucestershire in England.

Before and during the Roman occupation of Britain, all the native inhabitants of the island (other than the Pictish/Caledonian tribes of what is now northern Scotland—and also excepting the Lloegyr of greater south-east Britain^{[dubious – discuss]}) spoke Brythonic languages, a sub-family of the Insular Celtic languages, and were regarded as Britons. The topographical contrast between the mountainous western areas and the generally lower-lying areas to the east is reflected in the nature of ancient settlements, with the majority of hillforts in Britain found in this western area.

During the Roman occupation, the tribes of Wales (Ordovices, Deceangli, Demetae, and especially the Silures) were noted by Roman authors as fiercely resisting any occupation. As such the border area became a centre of military activity, with legions based at Deva (Chester), Viroconium (Wroxeter), and Isca Augusta (Caerleon).^{[citation needed]} In most of Wales, the militaristic nature of the occupation was in stark contrast to that of southeast Britain. As such, by the end of Roman rule, there would have been a cultural border, between the highly Romanised Romano-British in the east, and the more independent and tribal kingdoms to the west. This western area was, however, largely Christian, and a number of successor states attempted to continue Roman practices. The most successful of these were the Kingdom of Gwynedd in the northwest, the Kingdom of Gwent and Glywysing in the southeast, the Kingdom of Dyfed in the southwest and the Kingdom of Powys in the east. Powys roughly coincided with the territory of the Celtic Cornovii tribe whose civitas or administrative centre during the Roman period was at Viroconium. Gwynedd, at the height of its power, extended as far east as the Dee estuary. Gradually, from the 5th century onwards, pagan tribes from the east, including the Angles and Saxons, conquered eastern and southern Britain, which later became England. In the south, the Welsh kingdom of Gwent broadly covered the same area as the pre-Roman Silures, traditionally the area between the rivers Usk, Wye and the Severn estuary. It was centred at different times on Venta (Caerwent), from which it derived its name, and Isca Augusta (Caerleon). Gwent generally allied with, and at various times was joined with, the smaller Welsh kingdom of Ergyng, centred in present-day southern Herefordshire west of the Wye (and deriving its name from the Roman town of Ariconium); and the larger kingdom of Glywysing in modern Glamorgan. The name Glywysing may indicate that it was founded by a British native of Glevum (Gloucester).^{[citation needed]}

The Battle of Mons Badonicus, c. 500, could have been fought near Bath between the British, the victors, and Anglo-Saxons attempting to reach the Severn estuary, but its date and location are very uncertain and it may equally well have taken place in Somerset or Dorset. However, it is more certain that the Anglo-Saxon kingdom of Wessex emerged in the 6th and 7th centuries in the upper Thames valley, Cotswolds and Hampshire areas. In 577, the Battle of Deorham in the southern Cotswolds was won by the Anglo-Saxons, and led to Wessex extending its control to the Severn estuary and the cities of Gloucester, Cirencester, and Bath. This severed the land link between the Britons of Wales and those of the south west peninsula. By about 600, however, the area of modern Gloucestershire east of the Severn, as well as most of Worcestershire, was controlled by another group, the Hwicce, who may have arisen from intermarriage between Anglo-Saxon and British leading families, possibly the successors to the pre-Roman Dobunni. The Hwicce came increasingly under Mercian hegemony.^{[citation needed]}

At the Battle of Chester in 616, the forces of Powys and other allied Brythonic kingdoms were defeated by the Northumbrians under Æthelfrith. This divided the Britons of Wales from those in Northern England, including Lancashire, Cumbria, and south west Scotland, an area which became known as "Yr Hen Ogledd" or "the Old North". Within a few decades, the Welsh became engaged in further defensive warfare against the increasingly powerful kingdom of Mercia, based at Tamworth in what became the West Midlands of England. Shrewsbury, was conquered by Oswiu of Northumbria in 656 when he had become overlord of the Mercians. Powys then withdrew from the lowland areas now in southern Cheshire, Shropshire and Herefordshire, which became known to Welsh poets as "The Paradise of Powys". The areas were occupied by Anglo-Saxon groups who became sub-kingdoms of Mercia, the Wreocensǣte or Wrekinset in the northern part of what became Shropshire, and the Magonsæte in the southern part. Further south, the area north west of the Severn later known as the Forest of Dean seems to have remained in British (that is, Welsh) hands until about 760.