Complex sentence: In 827 or 828, he defended the veneration of images against Claudius, Bishop of Turin and wrote to refute some of his religious teachings at the request of the emperor Louis the Pious.
Split into simpler sentences: In 827 or 828, he defended the veneration of images against Claudius, Bishop of Turin. He wrote to refute some of the religious teachings of Claudius of Turin at the request of the emperor Louis the Pious.