been confronted with an invasion of Slavic tribes that threatened Constantinople from the Balkans. Only by virtue of his great skill as both a leader and a general did he manage to withstand these dualonslaughts. While the war between the Persians and the Byzantines wasn’t a religious conflict per se, the Persian king treated Heraclius with contempt, and Jerusalem was singled out for humiliation. In turn, as Heraclius began to reverse the tide, he destroyed Zoroastrian fire temples in revenge.
Heraclius proved his mettle as a leader and a commander when he repelled both the Slavs and the Sasanians. The culmination was the liberation of Jerusalem. Having achieved an improbable victory, Heraclius made a point of going to the holy city in 630. To great fanfare, he personally restored the True Cross to its place in the Anastasis (later called the Church of the Holy Sepulchre) and proclaimed the recent triumph of the empire as a victory for Christ. “There was much joy at his entrance to Jerusalem,” said a contemporary account, “sounds of weeping and sighs and abundant tears … extreme exaltation of the emperor, of the princes, of all the soldiers and inhabitants of the city; and nobody could sing the hymns of our Lord on account of the great and poignant emotion of the emperor and the whole multitude.” 4
But the war had taken a toll on both regimes, on their treasuries and their soldiers, and neither had recovered its full strength four years later when the successor to Abu Bakr, the caliph Umar ibn al-Khattab, ordered his forces to attack. The Persian Empire had descended into a brief but ruinous civil war, and Heraclius had withdawn in exhaustion from an active role in leading the Byzantine armies. In contrast to an emperor whose power was waning, the new caliph was a physical and military dynamo, an early convert known for his passionate, bristling persona and his unbridled allegiance to Muhammad. At some point during his rule, Umar acquired the title amir al-mumin , Commander of the Faithful, which became part of the moniker of all subsequent caliphs. Umar took the military dimension of his role seriously, and he executed it brilliantly.
Three battles essentially decided the fate of both empires. In 634, at Ajnadin, south of Jerusalem, and in 636, at Yarmuk, in Syria, the main Byzantine divisions in the region were wiped out by smaller, more mobile Arab forces. In 637, at the battle of Qadisiya, near the Euphrates, the Persian army led by General Rustam was annihilated. The Persian capital of Ctesiphon was occupied, and for the next decade and a half, the Sasanian emperor was pursued by Arab detachments across Persia until he was cornered and killed. To the west, in 639, the Muslim commanderAmr ibn al-As invaded Egypt. The cities of Alexandria and Heliopolis (north of modern Cairo) quickly fell, and by 641, all of Egypt was under the control of the caliph.
As Arab armies fanned out across the Near East and North Africa, they were faced with a problem: how were they going to govern the conquered people? Would there be a mass exodus of Arabs from the peninsula into the major urban centers? Would they raid and then retreat with the spoils? Would they isolate themselves from the Christians, Jews, and Zoroastrians that comprised the population of the conquered lands? And how would they handle societies that were primarily agricultural, that required a different social organization to keep irrigation works intact, to ensure harvests? Some Arabs had settled in cities like Mecca, but others were primarily nomadic, and not accustomed to living in one location year-round. There was nothing in the Quran to provide an easy answer to these new and urgent questions, and the breathtaking speed of the victories meant that there was no luxury to sit back and deliberate over options.
Because the Quran had been so explicit about the People of the Book, however, there was some guidance about how to treat the Christian populations