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

As such the border area became a centre of military activity, with legions based at Deva (Chester), Viroconium (Wroxeter), and Isca Augusta (Caerleon).

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.

[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.

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.

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.

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.

However, campaigns by Powys against Mercia led to the building of Wat's Dyke, an earthwork boundary extending from the Severn valley near Oswestry to the Dee at Basingwerk in what became Flintshire, perhaps to protect recently acquired lands.

As king, he rebuilt Mercia's hegemony over the southern English through military campaigns, and also caused the construction of Offa's Dyke, around the years 770 and 780.

The earthwork was generally dug with the displaced soil piled into a bank on the Mercian (eastern) side, providing an open view into Wales and suggesting that it was built by Mercia to guard against attacks or raids from Powys.

In the mid-20th century, Sir Cyril Fox completed a major survey of the Dyke and stated that it ran from the Dee to the Severn, as Asser suggested, but with gaps, especially in the Herefordshire area, where natural barriers of strong rivers or dense forests provided sufficient defence.

The system of shires which was later to form the basis of local administration throughout England and eventually Wales originated in Wessex, where it became established during the 8th century.

[7] However, after his most powerful ally – Earl Elfgar of Mercia and East Anglia – died, Harold and Tostig Godwinson took advantage of the situation – Gruffudd being besieged in Snowdonia – and invaded Wales.

It served as a base from which the Normans continued to expand westward into south Wales, establishing a castle at Caerleon and extinguishing the Welsh kingdom of Gwent.

William also installed Roger de Montgomerie at Shrewsbury, and Hugh d'Avranches at Chester, creating a new expansionist earldom in each case.

Hundreds of small castles, mostly of the motte and bailey type, were built in the border area in the 12th and 13th centuries, predominantly by Norman lords as assertions of power as well as defences against Welsh raiders and rebels.

Many new towns were established across the area, some such as Chepstow, Monmouth, Ludlow and Newtown becoming successful trading centres, and these tended to be a focus of English settlement.

[7][8] The Marches, or Marchia Wallia, were to a greater or lesser extent independent of both the English monarchy and the Principality of Wales, which remained based in Gwynedd in the north west of the country.

In ecclesiastical terms, the ancient dioceses of Bangor and St. Asaph in the north, and St. David's and Llandaff in the south, collectively defined an area which included both the Principality and the March, and coincided closely with later definitions of Wales.

Features of its independence were its separate legal jurisprudence based on the well-established laws of Cyfraith Hywel, and the increasingly sophisticated court of the Aberffraw dynasty.

[citation needed] However, the Marches remained outside the shire system, and at least nominally outside the control of the English monarchy, until the first Laws in Wales Act was introduced in 1535 under Henry VIII.

Henry had not seen the need to reform the government of Wales at the beginning of his reign, but gradually he perceived a threat from some of the remaining Marcher lords and therefore instructed his chief minister, Thomas Cromwell, to seek a solution.

The lordships of Ludlow, Clun, Caus and part of Montgomery were incorporated into Shropshire; and Wigmore, Huntington, Clifford and most of Ewyas were included in Herefordshire.

The parishes transferred to the Diocese of Lichfield were: Criftins, Hengoed, Kinnerley, Knockin, Llanyblodwell, Llanymynech, Melverley, Morton, Oswestry, St Martins, Selattyn, Trefonen, Weston Rhyn and Whittington.

[citation needed] In 1965, a separate government department, the Welsh Office, was established for Wales, and it assumed an increasing range of administrative responsibilities.

[37] By 1992, the Welsh Office oversaw housing, local government, roads, historic buildings, health, education, economic development, agriculture, fisheries and urban regeneration,[37] although the extent to which it was autonomous from England in public policy is a matter of debate.

[39] In 2008, residents of the village of Audlem, Cheshire, 9 miles (14 km) from the border, "voted" to become part of Wales in what was originally a joke ballot.

[46][47] In July 2017, the Welsh Secretary, Alun Cairns, announced that tolls would be abolished at the end of 2018, claiming that this would boost the South Wales economy by around £100m a year.