On his return from Rome, Dunstan at once regained his position as virtual prime minister of the kingdom. By his advice Ælfstan was appointed to the Bishopric of London, and Oswald to that of Worcester. In 963, Æthelwold, the Abbot of Abingdon, was appointed to the See of Winchester. With their aid and with the ready support of King Edgar, Dunstan pushed forward his reforms in the English Church. The monks in his communities were taught to live in a spirit of self-sacrifice, and Dunstan actively enforced the law of celibacy whenever possible. He forbade the practices of simony (selling ecclesiastical offices for money) and ended the custom of clerics appointing relatives to offices under their jurisdiction. Monasteries were built, and in some of the great cathedrals, monks took the place of the secular canons; in the rest the canons were obliged to live according to rule. The parish priests were compelled to be qualified for their office; they were urged to teach parishioners not only the truths of the Christian faith, but also trades to improve their position. The state saw reforms as well. Good order was maintained throughout the realm and there was respect for the law. Trained bands policed the north, and a navy guarded the shores from Viking raids. There was a level of peace in the kingdom unknown in living memory.