English-speaking peoples began to cross Offa's Dyke in substantial numbers when settlements were created by Edward 1st in his ambition to unite the whole of the island of Britain under his kingship. After a period of military conquest, the English king forced Welsh prince Llywelyn ap Gruffudd to give up most of his lands, keeping only Gwynedd west of the River Conwy.

Edward then followed up his successes by building English strongholds around the perimeter of what remained of Llewelyn's possessions, and strong, easily defended castles were erected at Flint, Rhuddlan, Aberystwyth, and Builth., garrisoned by large detachments of English immigrants and soldiers. Some of these towns have remained stubbornly English ever since. Urban settlement, in any case, was entirely foreign to the Celtic way of life.

In 1294, the Statute of Rhuddlan confirmed Edward's plans regarding the governing of Wales. The statute created the counties of Anglesey, Caernarfon, and Merioneth, to be governed by the Justice of North Wales; Flint, to be placed under the Justice of Chester; and the counties of Carmarthen and Cardigan were left under the Justice of South Wales.

In the year 1300, the situation seemed permanently established, when "King Edward of England made Lord Edward his son [born at Caernarfon Castle], Prince of Wales and Count of Chester," and ever since that date these titles have been automatically conferred upon the first-born son of the English monarch. The Welsh people were not consulted in the matter, although an obviously biased entry in Historia Anglicana for the year 1300 reads:

In this year King Edward of England made Lord Edward, his son and heir, Prince of Wales and Count of Chester. When the Welsh heard this, they were overjoyed, thinking him their lawful master, for he was born in their lands.

Following his successes in Wales, signified by the Statute of Rhuddlan, sometimes referred to as The Statute of Wales, Edward embarked on yet another massive castle-building program, creating such world-heritage sites of today as Caernarfon, Conwy, Harlech, and Beaumaris in addition to the earlier not so-well known (or well-visited) structures at Flint and Rhuddlan. Below their huge, forbidding castle walls, additional English boroughs were created, and English traders were invited to settle, often to the exclusion of the native Welsh, who must have looked on in awe and despair from their lonely hills at the site of so much building activity. Their ancestors must have felt the same sense of dismay as they watched the Roman invaders build their heavily defended forts in strategic points on their lands.

The Welsh were forbidden to inhabit such "boroughs" or to carry arms within their boundaries (even today, there are laws remaining on the statute books of Chester, a border town, that proscribe the activities of the Welsh within the city walls). With the help of the architect Master James of St. George, and with what must have seemed like limitless resources in manpower and materials, Edward showed his determination to place a stranglehold on the Welsh. Occasional rebellions were easily crushed; it was not until the death of Edward III and the arrival of Owain Glyndwr (Shakespeare's Owen Glendower), that the people of Wales felt confident enough to challenge their English overlords.

Owain Glyndwr was Lord of Glyndyfrdwy (the Valley of the Dee). He seized his opportunity in 1400 after being crowned Prince of Wales by a small group of supporters and defying Henry IV's many attempts to dislodge him. The ancient words of Geraldus Cambrensis could have served to inspire his followers:

The English fight for power; the Welsh for liberty; the one to procure gain, the other to avoid loss. The English hirelings for money; the Welsh patriots for their country

The comet that appeared in 1402 was seen by the Welsh as a sign of their forthcoming deliverance from bondage as well as one that proclaimed the appearance of Owain. His magnetic personality electrified and galvanized the people of Wales, strengthening their armies and inspiring their confidence. Even the weather was favorable.

The Welsh leader's early successes released the long-suppressed feelings of thousands of Welshmen who eagerly flocked to his support from all parts of England and the Continent. Before long, it seemed as if the long-awaited dream of independence was fast becoming a reality: three royal expeditions against Glyndwr failed: he held Harlech and Aberystwyth, had extended his influence as far as Glamorgan and Gwent, was receiving support from Ireland and Scotland; and had formed an alliance with France. Following his recognition by the leading Welsh bishops, he summoned a parliament at Machynlleth, in mid-Wales, where he was crowned as Prince of Wales.

It didn't seem too ambitious for Owain to believe that with suitable allies, he could help bring about the dethronement of the English king; thus he entered into a tripartite alliance with the Earl of Northumberland and Henry Mortimer (who married Owain's daughter