Battle of Orewin Bridge The Battle of Orewin Bridge ( also known as the Battle of Irfon Bridge ) was fought between English ( led by the Marcher Lords ) and Welsh armies on 11 December 1282 near Builth Wells in mid - Wales . It was a decisive defeat for the Welsh because their leader , Llywelyn ap Gruffydd was killed , and this effectively ended the independence of Wales . Background of the War . Llywelyn had already fought a war against Edward I of England in 1277 . Edward had organised a large full - time army with which he overran all North Wales as far west as the Conwy River , and a fleet with which he captured Anglesey , depriving the Welsh of much of their grain . Llywelyn was forced to come to humiliating terms , and ceded large areas of Wales to England . Over the five years which followed , there was continued tension between Llywelyn and Edward over various lawsuits , and increasing unrest between the Welsh people and their English administrators in the newly transferred areas . The revolt was actually begun in 1282 by Llywelyn ' s treacherous brother Dafydd , who had sided with Edward five years earlier but now captured Hawarden Castle and slaughtered its garrison . This was followed by uprisings in many parts of Wales , and Llywelyn declared war on Edward on behalf of all Welsh . Campaign up to December . Edward repeated his tactics of the previous war , laboriously occupying North Wales as far as the Vale of Conwy and occupying Anglesey , while sending armies into southern and central Wales to overawe or subdue Llewelyn ' s allies and potential supporters . At the Battle of Llandeilo Fawr the English army attacking south Wales was ambushed and destroyed by southern Welsh . On 6 November , Edward ' s lieutenant in Anglesey , Luke de Tany , launched a premature attack across a bridge of boats which spanned the Menai Strait . His force was ambushed , cut off and slaughtered at the Battle of Moel - y - don . These unexpected reverses undoubtedly set Edward back several months . He was forced to pause to raise fresh armies and supplies . Llywelyn took advantage of the respite by making an expedition into mid - Wales , to inspire and rally support . This was the territory nominally ruled by Marcher Lords , who enjoyed considerable independence from Edward . Some were wavering and prepared to support Llywelyn . However , three of them , Roger l ' Estrange , John Giffard and Edmund Mortimer were staunch supporters of Edward , and were in the field in mid - Wales with an army consisting mainly of archers from Shropshire and some heavy cavalry as well as troops donated to them by the Welsh lord Gruffydd ap Gwenwynwyn , who was an old enemy of Llywelyn . The English are thought to have an army consisting of around 5000 infantrymen and 1300 heavy cavalry . The battle . On 11 December , Llywelyn ' s army occupied a hillside north of the Irfon River near the village of Cilmeri , placed to repel any attack from the south across Orewin Bridge . The army is thought to have consisted of a few thousand spearmen and javelinmen from North Wales , with some men - at - arms from Llywelyn ' s own " teulu " ( household ) , and some local archers from Brecon ( who had betrayed their former English allies and joined Llywelyn having been disappointed in the English failure at the Battle of Llandeilo Fawr ) . Altogether , the army is thought to have added up to around 7000 infantry and 160 Cavalry ( Llywelyn ' s Teulu ) . Llywelyn himself was not present , having gone to speak with local leaders ( possibly at Builth Castle ) . A local inhabitant had told the Marchers about a ford across the Irfon two miles downstream near its confluence with the River Wye , and they sent most of their archers across it to attack the Welsh in the flank . The Welsh army turned to face them , and the English mounted men - at - arms charged across the now undefended bridge . Meanwhile the English archers shot into the Welsh spear schiltrons , weakening and disorganising the troops . The English heavy cavalry then charged the rear of the army . The leaderless and demoralised Welsh were routed . As the Welsh army fled , Llywelyn returned in haste . On the outskirts of the fighting , he was attacked and cut down by an English man - at - arms named Stephen de Frankton , an English centenar from Ellesmere , Shropshire . Aftermath . Llywelyn ' s body was not recognised until the next day . ( He had probably gone in secret or incognito to his meeting , and would therefore not have worn any surcoat or other heraldic device . ) His head was cut off , and taken to London to be exhibited . He left only an infant daughter , Gwenllian of Wales , and leadership of the Welsh fell on Dafydd , who led a guerrilla resistance for some months but was soon betrayed , captured and executed as a traitor . Edward was able to formally end the existence of an organised resistance to English rule in the Welsh regions . Whatever Llywelyn ' s own faults , Edward could not deny his claims as a legitimate ruler of Wales . Had Llywelyn lived and Edward suffered further reverses , it is theoretically possible that the war might have ended with Edward leaving at least part of an independent Wales ( though it is unlikely that Wales could have resisted English encroachment indefinitely ) .