IV.—­Gregory the Great

Justinian was succeeded by his nephew, Justin II., who lived to see the conquest of the greater part of Italy by Alboin, king of the Lombards (568-570), the disaffection of the exarch, Narses, and the ruin of the revived glories of the Roman world.

During a period of 200 years Italy was unequally divided between the king of the Lombards and the exarchate of Ravenna.  Rome relapsed into a state of misery.  The Campania was reduced to the state of a dreary wilderness.  The stagnation of a deluge caused by the torrential swelling of the Tiber produced a pestilential disease, and a stranger visiting Rome might contemplate with horror the solitude of the city.  Gregory the Great, whose pontificate lasted from 590 to 604, reconciled the Arians of Italy and Spain to the Catholic Church, conquered Britain in the name of the Cross, and established his right to interfere in the management of the episcopal provinces of Greece, Spain, and Gaul.  The merits of Gregory were treated by the Byzantine court with reproach and insult, but in the attachment of a grateful people he found the purest reward of a citizen and the best right of a sovereign.

The short and virtuous reign of Tiberius (578-582), which succeeded that of Justin, made way for that of Maurice.  For twenty years Maurice ruled with honesty and honour.  But the parsimony of the emperor, and his attempt to cure the inveterate evil of a military despotism, led to his undoing, and in 602 he was murdered with his children.  A like fate befell the Emperor Phocas, who succumbed in 610 to the fortunes of Heraclius, the son of Crispus, exarch of Africa.  For thirty-two years Heraclius ruled the Roman world.  In three campaigns he chastised the rising power of Persia, drove the armies of Chosroes from Syria, Palestine, and Egypt, rescued Constantinople from the joint siege of the Avars and Persians (626), and finally reduced the Persian monarch to the defence of his hereditary kingdom.  The deposition and murder of Chosroes by his son Siroes (628) concluded the successes of the emperor.

A treaty of peace was arranged, and Heraclius returned in triumph to Constantinople, where, after the exploits of six glorious campaigns, he peacefully enjoyed the sabbath of his toils.  The year after his return he made the pilgrimage to Jerusalem to restore the true Cross to the Holy Sepulchre.  In the last eight years of his reign Heraclius lost to the Arabs the same provinces which he had rescued from the Persians.

Heraclius died in 612.  His descendants continued to fill the throne in the persons of Constantine III. (641), Heracleonas (641), Constans II. (641), Constantine IV. (668), Justinian II. (685), until 711, when an interval of six years, divided into three reigns, made way for the rise of the Isaurian dynasty.

V.—­The New Era of Charlemagne

Leo III. ascended the throne on March 25, 718, and the purple descended to his family, by the rights of heredity, for three generations.  The Isaurian dynasty is most notable for the part it played in ecclesiastical history.