845 Truce with the Mohammedans.
847 Conversion of the Khazars to Christianity. The Bulgarians follow their example a few years later.
848 Revolt of the Paulicians, who join the Arabs.
854 Theodora retires to private life.
856 Bardas, her brother, becomes cæsar. Photius elected patriarch in place of the deposed Ignatius.
858 A great war with the Arabs begins. Omar lays Pontus waste. Successful campaign of Leo, the commander-in-chief, who is finally captured by the Mohammedans.
860 Michael badly defeated near Melitene.
862 Omar invades Cappadocia, Pontus, and Cilicia.
863 Battle of Amasia. Great victory of Petronas, the emperor’s uncle. Death of Omar. The end of trouble with the Mohammedans for some years.
865 First appearance of the Russians in the empire. They attack Constantinople, but are driven off.