The princes of Wales, notwithstanding the great power of the monarchs, both of the Saxon and Norman line, still preserved authority in their own country. Though they had often been constrained to pay tribute to the crown of England, they were with difficulty retained in subordination or even in peace; and almost through every reign since the conquest, they had infested the English frontiers with such petty incursions and sudden inroads, as seldom merit to have place in a general history. The English, still content with repelling their invasions, and chacing them back into their mountains, had never pursued the advantages obtained over them, nor been able, even under their greatest and most active princes, to fix a total, or so much as a feudal subjection on the country. This advantage was reserved to the present king, the weakest and most indolent. In the year 1237, Lewellyn, prince of Wales, declining in years and broken with infirmities, but still more harassed with the rebellion and undutiful behaviour of his younger son, Griffin, had recourse to the protection of Henry; and consenting to subject his principality, which had so long maintained, or soon recovered, its independance, to vassalage under the crown of England, had purchased security and tranquillity on these dishonourable terms. His eldest son and heir, David, renewed the homage to England; and having taken his brother prisoner, delivered him into Henry's hands, who committed him to custody in the Tower. That prince, endeavouring to make his escape, lost his life in the attempt; and the prince of Wales, freed from the apprehensions of so dangerous a rival, paid thenceforth less regard to the English monarch, and even renewed those incursions, by which the Welsh, during so many ages, had been accustomed to infest the English borders. Lewellyn, however, the son of Griffin, who succeeded to his uncle, had been obliged to renew the homage, which was now claimed by England as an established right; but he was well pleased to inflame those civil discords, on which he rested his present security, and founded his hopes of future independance. He entered into a confederacy with the earl of Leicester, and collecting all the force of his principality, invaded England with an army of 30,000 men. He ravaged the lands of Roger de Mortimer and of all the barons, who adhered to the crown[117]; he marched into Cheshire, and committed like depredations on prince Edward's territories; every place, where his disorderly troops appeared, was laid waste with fire and sword; and though Mortimer, a gallant and expert soldier, made stout resistance, it was found necessary, that the prince himself should head the army against this invader. Edward repulsed prince Lewellyn, and obliged him to take shelter in the mountains of North Wales: But he was prevented from making farther progress against the enemy, by the disorders, which soon after broke out in England.