Editing Llywelyn ab Iorwerth (section)

=== Treaty of Worcester and border campaigns 1218–1229 ===
[[File:Criccieth beach.JPG|thumb|[[Criccieth Castle|Criccieth]] is one of a number of castles built by Llywelyn.]]

Following King John's death Llywelyn concluded the [[Worcester, England|Treaty of Worcester]] with his successor Henry III in 1218.<ref name=DWB/> This treaty confirmed him in possession of all his recent conquests. From then until his death Llywelyn was the dominant force in Wales, though there were further outbreaks of hostilities with [[marcher lord]]s, particularly the [[Marshal family]] and [[Hubert de Burgh, Earl of Kent]], and sometimes with the king. Llywelyn built up marriage alliances with several of the Marcher families. One daughter, [[Gwladus Ddu]] ("Gwladus the Dark"), was already married to [[Reginald de Braose]] of Brecon and Abergavenny, but with Reginald an unreliable ally Llywelyn married another daughter, Marared, to [[John de Braose]] of [[Gower Peninsula|Gower]], Reginald's nephew. He found a loyal ally in [[Ranulf de Blondeville, 6th Earl of Chester]], whose nephew and heir, [[John of Scotland, Earl of Huntingdon]], married Llywelyn's daughter [[Elen ferch Llywelyn]] in about 1222. Following Reginald de Braose's death in 1228, Llywelyn also made an alliance with the powerful [[Roger Mortimer of Wigmore]] when Gwladus Ddu married as her second husband [[Ralph de Mortimer]].{{sfn|Lloyd|1911|pp=645, 657–658}}

Llywelyn was careful not to provoke unnecessary hostilities with the crown or the Marcher lords; for example, in 1220, he compelled [[Rhys Gryg]] to return four [[commote]]s in [[South Wales]] to their previous Anglo-Norman owners.{{sfn|Davies|1992|p=298}} He built a number of castles to defend his borders, most thought to have been built between 1220 and 1230. These were the first sophisticated stone castles in [[Wales]]; his castles at [[Criccieth Castle|Criccieth]], [[Deganwy Castle|Deganwy]], [[Dolbadarn Castle|Dolbadarn]], [[Dolwyddelan Castle|Dolwyddelan]] and [[Castell y Bere]] are among the best examples.{{sfn|Lynch|1995|p=135}} Llywelyn also appears to have fostered the development of quasi-urban settlements in Gwynedd to act as centres of trade.<ref>{{cite book |title=A History of Wales |last=Davies |first=John |author-link=John Davies (historian) |year=1994 |publisher=Penguin Books |edition=Reprint |isbn=978-0-140-14581-6 |page=142}}</ref>

Hostilities broke out with [[William Marshal, 2nd Earl of Pembroke]] in 1220. Llywelyn destroyed the castles of [[Narberth Castle|Narberth]] and [[Wiston Castle|Wiston]], burnt the town of [[Haverfordwest]] and threatened [[Pembroke Castle]], but agreed to abandon the attack on payment of £100. In early 1223, Llywelyn crossed the border into [[Shropshire]] and captured [[Kinnerley]] and [[Whittington Castle|Whittington]] castles. The Marshals took advantage of Llywelyn's involvement here to land near [[St David's]] in April with an army raised in [[Ireland]] and recaptured [[Cardigan, Ceredigion|Cardigan]] and [[Carmarthen]] without opposition. The Marshals' campaign was supported by a royal army which took possession of [[Montgomery, Powys|Montgomery]].<ref name=DWB/> Llywelyn came to an agreement with the king at Montgomery in October that year. Llywelyn's allies in South Wales were given back lands taken from them by the Marshals and Llywelyn himself gave up his conquests in Shropshire.{{sfn|Lloyd|1911|pp=661–663}}

In 1228, Llywelyn was engaged in a campaign against [[Hubert de Burgh, Earl of Kent|Hubert de Burgh]], who was [[Justiciar]] of England and Ireland and one of the most powerful men in the kingdom. Hubert had been given the lordship and castle of Montgomery by the king and was encroaching on Llywelyn's lands nearby. The king raised an army to help Hubert, who began to build another castle in the [[commote]] of Ceri. However, in October the royal army was obliged to retreat and Henry agreed to destroy the half-built castle in exchange for the payment of £2,000 by Llywelyn. Llywelyn raised the money by demanding the same sum as the ransom of [[William de Braose (died 1230)|William de Braose]], [[Abergavenny|Lord of Abergavenny]], whom he had captured in the fighting.{{sfn|Lloyd|1911|pp=667–670}}