Pope from 847. He at once set about repairing the damage done by the Saracens in 846, putting a wall round the part of Rome on the right bank of the Tiber (henceforth the ‘Leonine City’). In 850 he crowned Louis, son of Lothair, as co-emperor; he is said to have ‘hallowed’ Alfred as future king of England in 853. The Asperges is ascribed to him. Feast day, 17 July.