He succeeded in 1194 as LLYWELYN "Fawr/the Great" Prince of Gwynedd, Prince of All Wales. The Annales Cambriæ name "Lewelinus filius Gervasii filii Owini Guynet…princeps Walliæ".
The Annales Londonienses record the death "Id Apr" in 1240 of "Lewelinus princeps Norwalliæ". The Chronicle of the Princes of Wales records that "Llywelyn son of Iorwerth prince of Wales died…and was buried at Aberconway" in 1240. 1
He may have been born at Dolwyddelan, the royal manor of Nantconwy, over which his father had exercised a brief lordship which ended with his death at about the time of Llywelyn 's birth. The infant prince, being a potential menace to the power of his father's half-brothers in Gwynedd, probably grew up in Powys under the protection of his maternal relatives. Following an obscure period of apprenticeship in arms (he entered the turbulent arena of northern politics at a very tender age), he combined with his cousins, the sons of Cynan ap Owain, and in 1194 defeated his uncle, Dafydd I, seizing from him a share in the government of Perfeddwlad, which in 1197, he transformed into sole rulership. With the capture of Mold in 1199 he promised to become a leader of the calibre and vision of Owain Gwynedd; in fact, between 1199 and 1203, he restored the undivided sovereignty of his grandfather over the whole of Gwynedd, including Merioneth and Penllyn.
The attitude of the English crown remained for a time uncertain, until king John resolved on a policy of friendship which was marked by Llywelyn 's marriage in 1205 to Joan, the king 's natural daughter. Good relations broke down in 1210, and in 1211, a royal expedition into Wales resulted in Llywelyn 's isolation and the loss of Perfeddwlad [the ‘Four Cantreds’]. These territories were re-taken in 1212, and there followed the years of his greatest military triumphs, for he took the fullest advantage of external events which culminated in ‘ Magna Carta,’ ruthlessly attacking the Marches and capturing, among other strongholds, the key positions of Carmarthen, Cardigan, and Montgomery. These he retained in custody by the treaty of Worcester ( 1218 ).
Meanwhile he had secured mastery over his fellow-princes. His greatest rival among the native lords of Wales, Gwenwynwyn of southern Powys, was finally exiled in 1216, and his lands remained in Llywelyn 's custody to the end. The princes of northern Powys were friendly, and after 1216 no serious problem was caused by the princes of the house of Dinefwr, whose lands Llywelyn had, in that year, re-allocated among them at a solemn assembly ‘ all of the Welsh princes and all the wise men of Gwynedd ’ held at Aberdovey.
Henceforth his position was never seriously threatened. The antagonism of the Marshalls, it is true, led to the loss of Carmarthen, Cardigan, and Montgomery in 1223, but he again acquired strategic outposts with the acquisition of Builth from William de Breos in 1229, and the re-capture of Cardigan, 1231, at a time when he was engaged in meeting the menace caused by the consolidation of vast territorial interests in the march by certain royal officials, notably Hubert de Burgh. This phase was concluded with the ‘ Pact of Middle ’ ( 1234 ) which virtually established peace for the remainder of Llywelyn 's life. He hoped to preserve the integrity of his dominions by introducing primogeniture in place of the native custom of partible succession, and a step towards that end had already been taken when, in 1229, Henry III had acknowledged Dafydd, Joan 's son, as Llywelyn 's sole successor, to the exclusion of an elder brother, Gruffydd. A statesmanlike desire to conciliate his neighbours of the march is seen in the marriages which he arranged for his children: Dafydd was m. to Isabella de Breos; Gwladus to Reginald de Breos and as a widow to Ralph Mortimer; Margaret was married to John de Breos and afterwards to Walter Clifford; Gwenllian m. William de Lacy, and Helen m. John, the nephew of her father's closest ally, Ranulf, earl of Chester.
A great feudal magnate — for Llywelyn 's policy was conceived within the limitations imposed by obligations of homage to the English crown, he envisaged Wales as a feudal principality on the same model as the Scottish monarchy; and though there is no evidence that he ever attempted to impose more than ‘de facto’ suzerainty over the native lords of Wales, there are indications that during his closing years he was steadily shaping a constitutional policy of the kind brought to fruition by his grandson and namesake. There was the subtle assumption after 1230 of a new style — ‘ Prince of Aberffraw and Lord of Snowdon ’ — and the more open move taken in 1238 at Strata Florida when, despite protests from the English court, fealty to Dafydd was exacted from subordinate Welsh lords. He d. on 11 April 1240 at Aberconwy, where he was buried in the abbey, of which he was the greatest benefactor. 2
14 Aug 1219
Order and injunction to Llywelyn, Prince of North Wales, by the obligation of the oath by which he is bound to the king and putting off all delay and excuse, to take into the king’s hand all demesne lands pertaining to the king’s castle of Carmarthen and all reasonable escheats whoever held them without warrant from King John, father of the king, or other kings of England, or from the king....
Calendar of Fine Rolls, 3 Hen. III, 366
11 Aug 1222, Oxford
Order to Llywelyn, Prince of North Wales to take into the king’s hand all land that Rhys ap Gruffydd, who is dead, held of the king in chief, and to keep it safely until the king orders otherwise....
Calendar of Fine Rolls, 6 Hen. III, 256
6 Jun 1232, Gloucester
John of Monmouth has respite, until 15 days from St. John the Baptist, from rendering his account for the arrears of the county of Wiltshire and from other debts for which he ought to have answered at the Exchequer on the same day, because he cannot appear before the barons of the Exchequer to answer for that account on Thursday next after Trinity in the same year because the king has sent him to the parts of Wales to make amends for breaches made in the truces taken between the king and Llywelyn, so that he is to be there then in the state in which he now is.
Calendar of Fine Rolls, 16 Hen. III, 131