Reigned from 827 to 844. Born in Rome, Italy; died there. A cardinal-priest, he was the choice of the Roman nobility. During most of his pontificate he was involved in attempts to restore harmony between Emperor Louis the Pious and his sons. He fortified Ostia against the Saracens, repaired aqueducts and churches, and made Saint Anschar first Archbishop of Hamburg in order to encourage his mission to the Scandinavians.