Editing Llywelyn ab Iorwerth (section)

{{Short description|Prince of Gwynedd and de facto Prince of Wales}}
{{redirect|Llywelyn Fawr|the 13th-century Lord of Meirionnydd|Llywelyn Fawr ap Maredudd}}
{{use British English|date=August 2019}}
{{use dmy dates|date=August 2019}}
{{Infobox royalty
| name         = Llywelyn ab Iorwerth
| title        = Prince of Aberffraw<br/>Lord of Snowdon
| image        = NLW Wynnstay Estate , Ystrad Marchell Charters 58 (seal 1) front, cropped.png
| image_size   = 225
| caption      = Seal-impression of Llywelyn from a charter dated 25 November 1209 in which Llywelyn granted land to the monks of [[Strata Marcella]]{{sfn|Pryce|2005|p=385}}
| native_lang1 = [[Welsh language|Welsh]]
| succession   = [[List of rulers of Gwynedd|King of Gwynedd]]
| reign        = 1195–1240
| predecessor  = [[Dafydd ab Owain Gwynedd]]
| successor    = [[Dafydd ap Llywelyn]]
| spouse       = [[Joan, Lady of Wales]]
| issue        = {{ubl|[[Dafydd ap Llywelyn]]|[[Gruffudd ap Llywelyn Fawr|Gruffudd ap Llywelyn]]|[[Elen ferch Llywelyn]]|[[Gwladus ferch Llywelyn|Gwladus Ddu]]|Marared ferch Llywelyn|[[Angharad ferch Llywelyn]]|Susanna ferch Llywelyn|[[Tegwared y Bais Wen|Tegwared ap Llywelyn]]}}
| house        = [[House of Aberffraw|Aberffraw]]
| father       = [[Iorwerth Drwyndwn]]
| mother       = Marared ferch Madog
| birth_date   = {{circa|1173}}<ref>{{cite book |doi=10.1002/9781444338232.wbeow367 |chapter=Llywelyn the Great (c. 1173–1240) |title=The Encyclopedia of War |year=2011 |last1=Brough |first1=Gideon |last2=Marsden |first2=Richard |isbn=9781405190374}}</ref>
| birth_place  = [[Dolwyddelan]]
| death_date   = 11 April 1240
| death_place  = [[Aberconwy Abbey]]
| burial_place = [[Aberconwy Abbey]]
}}

'''Llywelyn ab Iorwerth''' ({{IPA|cy|ɬəˈwɛlɪn ab ˈjɔrwɛrθ|pron}}, {{circa|1173}} – 11 April 1240), also known as '''Llywelyn the Great''' ({{langx|cy|Llywelyn Fawr}}, {{IPA|cy|ɬəˈwɛlɪn vaʊ̯r|}}; {{langx|la|Leolinus Magnus}}), was a medieval Welsh ruler. He succeeded his uncle, [[Dafydd ab Owain Gwynedd]], as [[List of rulers of Gwynedd|King of Gwynedd]] in 1195. By a combination of war and diplomacy, he dominated Wales for 45 years.

During Llywelyn's childhood, Gwynedd was ruled by two of his uncles, who split the kingdom between them, following the death of Llywelyn's grandfather, [[Owain Gwynedd]], in 1170. Llywelyn had a strong claim to be the legitimate ruler and began a campaign to win power at an early age. He was sole ruler of Gwynedd by 1200 and made a treaty with King [[John of England]] that year. Llywelyn's relations with John remained good for the next ten years. He married John's natural daughter [[Joan, Lady of Wales|Joan]] in 1205, and when John arrested [[Gwenwynwyn]] of [[Powys]] in 1208, Llywelyn took the opportunity to annex southern Powys. In 1210, relations deteriorated, and John invaded Gwynedd in 1211. Llywelyn was forced to seek terms and to give up all lands east of the [[River Conwy]] but was able to recover them the following year in alliance with the other Welsh princes. He allied himself with the barons who forced John to sign [[Magna Carta]] in 1215. By 1216, he was the dominant power in Wales, holding a council at [[Aberdyfi]] that year to apportion lands to the other princes.

Following King John's death, Llywelyn concluded the Treaty of Worcester with his successor, [[Henry III of England|Henry III]], in 1218. During the next fifteen years, Llywelyn was frequently involved in fights with [[Welsh Marches|Marcher]] lords and sometimes with the king, but also made alliances with several major powers in the Marches. The Peace of Middle in 1234 marked the end of Llywelyn's military career, as the agreed truce of two years was extended year by year for the remainder of his reign. He maintained his position in [[Wales]] until his death in 1240 and was succeeded by his son [[Dafydd ap Llywelyn]].