When Edward invaded Wales in 1282, Peckham, moved with a desire for peace and with compassion for the Welsh, endeavoured to persuade Llewelyn to submit to the English king, and, contrary to Edward's will, went alone to Llewelyn's fortress of Aber, and tried to arrange terms. When his efforts proved in vain, he wrote an angry and irritating letter to the Welsh prince. Nevertheless he exerted himself on behalf of the Welsh clergy, prayed Edward to allow the clerks in Snowdon to leave the country with their goods, wrote indignantly to Burnell to complain that some clerks had been hanged at Rhuddlan, "to the reproach of the clergy and the contempt of the Church," and exhorted the king to restore the churches that had been destroyed in the war. The backward and disorderly condition of the Welsh Church caused him much concern, and he urged the bishops of Bangor and St. Asaph's to put a stop to the concubinage or marriage of the clergy, their unseemly dress, and their neglect of their duties, to insist on the observance of the decrees of Otho and Ottoboni, and to do all in their power to overcome the angry feelings of their flocks towards the English, so that the very word "foreignry" might no more be used among them. Moreover, he was anxious to see the Welsh become civilized, and wrote to Edward advising him to encourage them to settle in towns and follow industries, and, as there were no means of education in Wales, to make the Welsh boys come to England and be taught there, instead of entering the household of a native prince, where they learnt nothing but robbery. Indeed, it would have been well for Wales had Peckham's wishes on these and other matters been carried out. The war taxed the king's resources severely, and, towards the end of it, Edward ordered the seizure of the money that, in accordance with a decree of the Council of Lyons, had been collected for a crusade, and stored in various great churches in England. This brought an indignant letter from Pope Martin IV. Before its arrival, however, the king had promised that the money should be refunded. Not content with a promise, the archbishop went off to meet Edward at Acton Burnell, and prevailed on him to make immediate restitution. [Sidenote: Limits of spiritual jurisdiction defined.]