Thus came to an end the old imperial system of dividing military authority and civil jurisdiction, which Augustus had invented and Diocletian perpetuated. [pg 169] Under stress of the fearful Saracenic invasion the civil governors disappear, and for the future a commander chosen for his military capacity has also to discharge civil functions.
Constans II., when once he had made peace with Moawiah, would have done well to turn to the Balkan Peninsula, and evict the Slavs from the districts south of Haemus into which they had penetrated during the reign of Heraclius. But he chose instead to do no more than compel the Slavs to pay homage to him and give tribute, and set out to turn westward, and endeavour to drive the Lombards out of Italy. Falling on the Duchy of Benevento, he took many towns, and even laid siege to the capital. But he failed to take it, and passed on to Rome, which had not seen the face of an emperor for two hundred years. When an emperor did appear he brought no luck, for Constans signalized his visit by taking down the bronze tiles of the Pantheon and sending them off to Constantinople [664].
The Emperor lingered no less than five years in the West, busied with the affairs of Italy and Africa, till the Constantinopolitans began to fear that he would make Rome or Syracuse his capital. But in 668 he was assassinated in a most strange manner. “As he bathed in the baths called Daphne, Andreas his bathing attendant smote him on the head with his soap-box, and fled away.” The blow was fatal, Constans died, and Constantine his son reigned in his stead.
Constantine IV., known as Pogonatus, “the Bearded,” reigned for seventeen years, of which more than half were spent in one long struggle with the [pg 170] Saracens. Moawiah, the first of the Ommeyades, had now made himself sole Caliph; the civil wars of the Arabs were now over, and once more they fell on the empire. Constantine's reign opened disastrously, with simultaneous attacks by the armies and fleets of Moawiah on Africa, Sicily, and Asia Minor. But this was only the prelude; in 673 the Caliph made ready an expedition, the like of which had never yet been undertaken by the Saracens. A great fleet and land army started from Syria to undertake the siege of Constantinople itself, an enterprise which the Moslems had not yet attempted. It was headed by the general Abderrahman, and accompanied by Yezid, the Caliph's son and heir. The fleet beat the imperial navy off the sea, forced the passage of the Dardanelles, and took Cyzicus. Using that city as its base, it proceeded to blockade the Bosphorus.
The great glory of Constantine IV. is that he withstood, defeated, and drove away the mighty armament of Moawiah. For four years the investment of Constantinople lingered on, and the stubborn resistance of the garrison seemed unable to do more than stave off the evil day. But the happy invention of fire-tubes for squirting inflammable liquids (probably the famous “Greek-fire” of which we first hear at this time), gave the Emperor's fleet the superiority in a decisive naval battle. At the same time a great victory was won on land and thirty thousand Arabs slain. Abderrahman had fallen during the siege, and his successors had to lead back the mere wrecks of a fleet and army to the disheartened Caliph.
It is a thousand pities that the details of this, the [pg 171] second great siege of Constantinople, are not better known. But there is no good contemporary historian to give us the desired information. If he had but met with his “sacred bard,” Constantine IV. might have gone down to posterity in company with Heraclius and Leo the Isaurian, as the third great hero of the East-Roman Empire.
The year after the raising of the great siege, Moawiah sued for peace, restored all his conquests, and offered a huge war indemnity, promising to pay 3000 lbs. of gold per annum for thirty years. The report of the triumph of Constantine went all over the world, and ambassadors came even from the distant Franks and Khazars to congratulate him on the victory which had saved Eastern Christendom from the Arab.
While Constantine was defending his capital from the Eastern enemy, the wild tribes of his northern border took the opportunity of swooping down on the European provinces, whose troops had been drawn off to resist the Arabs. The Slavs came down from the inland, and laid siege for two years to Thessalonica, which was only relieved from their attacks when Constantine had finished his war with Moawiah. But a far more dangerous attack was made by another enemy in the eastern part of the Balkan Peninsula. The Bulgarians, a nomad tribe of Finnish blood, who dwelt in the region of the Pruth and Dniester, came over the Danube, subdued the Slavs of Moesia, and settled between the Danube and the Eastern Balkans, where they have left their name till this day. They united the scattered Slavonic tribes [pg 172] of the region into a single strong state, and the new Bulgarian kingdom was long destined to be a troublesome neighbour to the empire. The date 679 counts as the first year of the reign of Isperich first king of Bulgaria. Constantine IV. was too exhausted by his long war with Moawiah to make any serious attempt to drive the Bulgarians back over the Danube, and acquiesced in the new settlement.
The last six years of Constantine's reign were spent in peace. The only notable event that took place in them was the meeting at Constantinople of the Sixth Oecumenical Council in 680-1. At this Synod, the doctrine of the Monothelites, who attributed but one will to Our Lord, was solemnly condemned by the united Churches of the East and West. The holders of Monothelite doctrines, dead and alive, were solemnly anathematised, among them Pope Honorius of Rome, who in a previous generation had consented to the heresy.
Constantine IV. died in 685, before he had reached his thirty-sixth year, leaving his throne to his eldest son Justinian, a lad of sixteen.