turned to Gwynedd. But his attack on the Mortimers reopened hostilities all along the marches. Moreover, the Mortimers and most of the marchers were hot partisans of the king against the barons, and Llywelyn consequently threw himself on the baronial side. As the son of Iorwerth had aided the barons in the struggle for Magna Carta, so now did the son of Gruffydd join hands with Simon de Montfort in his struggle with Henry III. Furthermore, Edward, who since 1254 had been the first of the marchers, was now the mainstay of his father's cause, and Llywelyn was thus again in open enmity to the future king of England.
Llywelyn's attack on the Mortimers had excited general consternation. Early in 1263 Peter of Aigueblanche, the Savoyard bishop of Hereford, wrote urgently to King Henry pressing for immediate assistance (Fœdera, i. 423). Henry wrote with equal persistence to his son, bidding him return to England and march against the Welsh (ib.) By April Edward was at Shrewsbury, preparing for an expedition (ib. i. 425). But civil war had already broken out between king and barons, and Edward had no leisure to castigate Llywelyn. Llywelyn readily suppressed a fresh revolt of his brother Davydd [q. v.], who was soon forced to flee to England, and he gained a new ally in his old foe, Gruflydd ab Gwenwynwyn, who did homage to him, and sought with his lord's help to drive the English out of his old territories in Powys. The close alliance with Montfort of Gilbert of Clare (1243-1295) [q. v.],the new earl of Gloucester, and lord of the Glamorgan palatinate, gave Llywelyn a powerful and unwonted support. He was therefore able to take the offensive against Edward with great effect. He again overran the four cantreds of Perveddwlad. Early in August he took the castle of Diserth, near Rhyl. On 29 Sept. the famine-stricken garrison of Deganwy surrendered to Llywelyn the strongest and most famous of the English fortresses in North Wales (Annales Cambria, p. 101; Rishanger, p. 20; Flores Hist. ii. 483). Meanwhile Gruffydd ab Gwenwynwyn destroyed the castle of Gwyddgrug. Other allies of Llywelyn took the castle of Radnor. Edward, who could hold with difficulty the border fortress of Hay, was forced to make a truce (Wikes, p. 133). In September Henry accepted the truce, though it did not for a moment check the victorious advance of Llywelyn (Fœdera, i. 433).
Early in 1264 the decisive struggle of the barons began. In February Henry sought, by cutting down the bridges over the Severn, to prevent a junction between Montfort and Llywelyn (Bémont, Simon de Montfort, p. 209, from Close Rolls). On 14 May Henry was defeated and taken prisoner by Llywelyn's allies at Lewes. The effect was immediate. 'That year,' says the Welsh chronicler (p. 353), 'the Welsh enjoyed peace from the English, Llywelyn, son of Gruffydd, being prince of all Wales.' In December the lords of the marches rose in revolt against Montfort's government, but the earl easily crushed their rebellion with the aid of Llywelyn. In this campaign Simon ravaged the lands of Roger Mortimer, penetrating as far as Montgomery. In March Montfort received the earldom of Chester, an acquisition which made his connection with Llywelyn doubly important. But on 28 May 1265 the escape of Edward, and his alliance with the Earl of Gloucester, now an open enemy of Simon, renewed the civil war. Edward and Gloucester held the left bank of the Severn, and strove to prevent Montfort, who was at Hereford with the captive king, from crossing the river to carry on the war in England. All depended upon Llywelyn's co-operation. On 22 June the puppet king was forced to sign a convention which, by restoring to Llywelyn large territories, including Maud's castle, Hawarden, Ellesmere, and Montgomery, and granting him the 'Principality,' with the homage of all the Welsh magnates, was to bind him still more closely to the cause of Leicester (Fœdera, i. 457; Waverley Annals, p. 363; Chronicle of Battle Abbey, in Bémont, p. 379). It was probably at this time that the plan of a marriage between Llywelyn and Eleanor, daughter of Simon de Montfort and niece of the king, was first broached (cf. Trivet, p. 294). Llywelyn once more spread desolation amidst the marches. But Montfort, on managing to cross the Severn, shifted the campaign from Wales, and on 3 Aug. 1265 he was slain at Evesham.
The remnants of the baronial party, the 'disinherited,' who still held out against Henry and his son, and soon sank into a little band of bold desperadoes, were congenial allies to Llywelyn, who now renewed with the younger Simon the close connection that he had formed with his father (Worcester Annals, p. 456). In September Llywelyn made so destructive an inroad into Cheshire that the great council at Winchester, where the victorious party was maturing its scheme of vengeance, was postponed for a month (Waverley Annals, p. 366). Henry now sent Maurice Fitzgerald and Hamon L'Estrange [see under Le Strange, John] to act against Llywelyn, while Pope Clement IV warned the Welsh prince of the perils incurred by
