But as poor as the empire’s fortunes were at Heraclius’s death, without him they would have been immeasurably worse. If he hadn’t arrived to overthrow Phocas, the empire would have fallen easy prey to the Persians; and when the Islamic tide came rushing out of Arabia, there would have been nothing to shield Europe from the flood. Instead, by combining a touch of Justinian’s vision with more than a hint of Belisarius’s generalship, Heraclius had made Constantinople a bulwark against Islamic aggression, diverting the Muslim advance into the long wastes of North Africa and delaying its entrance into Europe. His early years had seen one glorious victory after another, and had he died after the overthrow of Chosroes II, with the Persian Empire defeated and the True Cross restored to Jerusalem, his subjects would have remembered him as one of the greatest emperors to sit on the Byzantine throne.
His reign saw the great turning point for much of the Middle East. For a thousand years, these lands had been Hellenized, ruled by a Roman Empire at first pagan and then Christian. They had contributed much to classical civilization, providing some of the finest emperors, theologians, saints, and poets of the classical world. After the Arab invasions, however, all that changed. Arabic replaced Greek as the lingua franca, and Islam replaced Christianity. Wrenched out of the Mediterranean orbit, these lands began to look to Damascus, then Baghdad, instead of Rome or Constantinople. A way of life that had more than a millennium came to a violent and abrupt end. Life in the Middle East would never be the same again.
Of the next five emperors who succeeded Heraclius, only one was older than sixteen when he gained the throne, and all were crippled by the struggles of powerful factions to assert control. Each defeat further diminished their authority and crippled their ability to fight back. Had a stronger ruler than the dying Heraclius been on the throne to confront the Muslims in 633, the subsequent history of the entire Middle East would have been radically different, but he was a sick man, and the imperial teenagers who succeeded him couldn’t grab hold of power firmly enough to effectively oppose the Islamic advance. By the middle of the century, the opportunity to contain the threat had passed, and the Arab conquest picked up an irresistible momentum. Frightened Byzantine citizens paraded their holy icons around the walls, invoking divine aid, but still the Muslim tide rolled on, destroying centuries of Roman rule and leaving the empire profoundly shocked in its wake. To many, it must have seemed a terrible divine judgment, and the emotional trauma seemed to paralyze Byzantium.
The unwieldy imperial army was marshaled to defend the long frontier, but the Arabs seemed impossible to contain. The impenetrable desert had always offered a feeling of safety for the Byzantines, but now it was a terrifying weakness. Using the stars to navigate across the featureless landscape, the Arabs slaughtered the camels they rode to consume their water, and emerged unexpectedly behind imperial lines. Whenever the Byzantine army did manage to confront them, the Arabs simply melted back into the desert, only to erupt somewhere else. Only once did an imperial army try to follow them. In 636, it pursued a Muslim army to a tributary of the Jordan River and suffered an appalling defeat. Those who survived the initial fighting tried to surrender but were massacred on the spot. The watching Mediterranean world was put on terrible notice: For those who resisted the Islamic sword, there would be no mercy.
Unnerved by the speed and ferocity of the attack, the East virtually threw away its defenses. Eight years after conquering Jerusalem, the Arabs entered Egypt, and at the sight of the Muslim forces, Alexandria, seat of one of the five great patriarchates of the church, voluntarily surrendered. The dissident Christians who had invited the invaders in soon found their new masters to be considerably less tolerant than the orthodox regime they had swept away, but by then it was too late. A popular uprising ejected the Muslim garrison, but it returned with an army at its back. Battering their way inside, the forces of Islam razed the walls, burned what remained of the library, and moved the capital to Al-Fustat—a small village in the shadow of the pyramids that would later become Cairo.*
Only the waters of the Mediterranean seemed to form a barrier capable of checking the desert-dwelling Arabs, but they learned quickly. Navigating at sea was not so different from navigating in the desert, and within a decade, they had constructed a navy and inflicted a crushing defeat of the formerly invincible Byzantine navy.