The English conquest of Wales (1094-1284) was the long military process by which England was able to conquer the Welsh petty kingdoms (later united under the Principality of Wales.
Background[]
After the Norman conquest of England, Norman lords established themselves on the borderlands and made inroads into Welsh territory. A series of castles, such as Chepstow and Caerleon, were built, diminishing Welsh autonomy. The Welsh struck back in 1094 and almost all of these were desetroyed. For some time after this, English kings were preoccupied elsewhere.
History[]
By 1218, Llywelyn the Great had united Gwynedd under his rule and swept away much of the English royal control in the south. At first, King John of England had found Llywelyn a useful counterbalance to the earls of Chester, but while John was preoccupied with a civil war against the barons in 1215-17, Llywelyn formed an alliance of Welsh princes and seized the royal castles of Cardigan and Carmarthen, as well as occupying southern Powys.
Although the 1218 Treaty of Worcester allowed Llywelyn to keep his gains, in 1223 William Marshal seized Cardigan and Carmarthen. Montgomery was also regained for the English. Llywelyn, however, recovered most of these losses in the early 1230s, and after this Wales was mostly at peace until his death in 1240.
Llywelyn's successor Dafydd ap Llywelyn paid homage to King Henry II of England for the whole of Gwynedd, but his authority was undermined by the attempts of his half-brother Gruffydd ap Llywelyn Fawr to unseat him. Dafydd reached out to Louis IX of France, offering to hold Wales from the Pope (and thus independently of Henry III) and implicitly offering support to the French king in his wars against the English. Henry's reaction was weak, even failing to take advantage of Gruffudd's death in 1246 to make advances. Instead, he made the 1247 Treaty of Woodstock with Gruffudd's two sons Owain and Llywelyn, by which the strategic Four Cantrefs between Conwy and the Dee were ceded to England.
Llywelyn ap Gruffudd - often known as Llywelyn Fawr, "the Last" - had pushed his brother aside and in 1258 he seized the Four Cantrefs back and assumed the title Prince of Wales. Henry III, who had problems enough with the barons' revolt led by Simon de Montfort, was again in no position to react. In 1267, the Treaty of Montgomery finally acknowledged Llywelyn's right to the princely title, in exchange for a fee of 25,000 marks.
The end of Welsh independence[]

Map of Wales in 1267
It looked as though Welsh independence under the overlordship of Gwynedd was secured, but disputes over the treaty led to Llywelyn's repudiation of it in 1271. Henry III died in 1272 while his heir, Edward I of England, was away on crusade, so it was not until 1276 that the new Englsih king invaded. Llywelyn Fawr had made himself unpopular with other Welsh rulers whose lands he had absorbed, and they rapidly submitted to Edward. With the English king advancing on Deganwy with an army of 15,000, and en English fleet landing at Anglesey, Llywelyn submitted.
He was stripped of all his territories outside Gwynedd, but even then, native rule might have survived there had it not been for his brother Dafydd, who felt himself slighted by the claims of an English lord, Reginald de Grey, to the part of the Four Cantrefs he had received as a reward for fighting on Edward I's side. On 22 March 1282, Dafydd attacked Hawarden Castle, while his confederates among the Welsh princes seized a number of other key Norman castles. Llywelyn hesitated, but felt he had no choice other than to join his brother's insurrection. Early successes were followed by a disastrous battle near Builth on 11 December, where the Welsh army was cut to pieces and Llywelyn killed. Most of the Welsh princes were dispossessed and Edward I took control of virtually the whole of Wales.
Aftermath[]
Llywelyn's daughter, Gwenllian of Wales, was born in 1282. She was taken to a nunnery in Lincolnshire by Edward I, where she remained until her death in 1337. Edward I moved quickly to organize his new dominion, issuing the Statute of Wales in March 1284, by which he extended the English shire system into Wales and established a number of officials to administer the principality. Rebellions, including that of Rhys ap Maredudd of Ystrad Tywi, one of the few Welsh princes allowed fo keep his lands in 1283, and by Madog ap Llywelyn in 1294-95 were put down. In 1301, Edward I's son, Edward of Caernarvon, was made Prince of Wales, a title that has been used by the heir apparent of the British royal family to this day. Wales was largely quiet until the rebellion of Owain Glyndwr in 1400.