Seeking to capitalize on this naval victory and the enthusiasm of the Christians, Leo had the retreating Muslim fleets pursued on land, and many Muslims were cut down. Simultaneously, the neighboring Bulgars — who, though occasionally hostile to the Christian empire, had no love for the new invaders, the Muslims — were persuaded by Leo’s “gifts and promises” into attacking and ultimately killing as many as 22,000 of Maslama’s battle-weary, half-starved men.
To make matters worse, “a report was dexterously scattered that the Franks, the unknown nations of the Latin world, were arming by sea and land in defense of the Christian cause, and their formidable aid was expected.” (It would be another three centuries before the Franks and Muslims would engage in a military conflict, spanning over two centuries, that would come to be known as the Crusades.)
By now, even the distant caliph realized that all was lost. Maslama, who could only have welcomed the summons, was recalled; and, on August 15 — according to most chroniclers, precisely one year to the day after it began — the siege of Constantinople was lifted.
Still, the Muslims’ troubles were far from over. Nature was not through with them. A terrible sea-storm is said to have all but annihilated the retreating ships, so that, of the 2,560 ships embarking back to Damascus and Alexandria, only ten remained — and of these, half were captured by the Byzantines, leaving only five to make it back to the caliphate and report the calamities that had befallen them (which may be both why the Arab chroniclers are curiously silent about the particulars of these events, and why it would be centuries before Constantinople would be similarly attacked again).
This sea-storm also led to the popular belief that divine providence had intervened on behalf of Christendom, with historians referring to August 15 as an “ecumenical date.” Meanwhile, in the Islamic world, this defeat, earthquakes in Palestine, and the death of Caliph Omar II in 720 (having been caliph in the year 100 of the Islamic calendar) boded an apocalyptic end to the world.
Of the original 200,000 Muslims who set out to conquer the Christian capital and additional spring reinforcements, only some 30,000 ever made it back alive. By way of retribution and before dying, a bitter and vindictive Omar, failing to subdue the Christians across the way, was quick to project his wrath on those Christians, the dhimmis, living under Islamic authority: He forced many of them to convert to Islam, killing those who refused.
It is difficult to exaggerate the significance of this battle. That Constantinople was able to repulse the caliphate’s hordes is one of Western history’s most decisive moments: Had it fallen, “Dark Age” Europe — chaotic and leaderless — would have been exposed to the Muslim invaders. And, if history is any indicator, the last time a large expanse of territory was left open before the sword of Islam, thousands of miles were conquered and consolidated in mere decades, resulting in what is known today as Dar al-Islam, or the “Islamic world.”
Indeed, this victory is far more significant than its more famous Western counterpart, the Frankish victory over the Muslims at the Battle of Tours, led by Charles Martel (the “Hammer”) in 732. Unlike the latter, which, from a Muslim point of view, was first and foremost a campaign dedicated to rapine and plunder, not conquest — evinced by the fact that, after the initial battle, the Muslims fled — the siege of Constantinople was devoted to a longtime goal, had the full backing of the caliphate, and consisted of far greater manpower. Had the Muslims won, and since Constantinople was the bulwark of Europe’s eastern flank, there would have been nothing to prevent them from turning the whole of Europe into the northwestern appendage of Dar al-Islam.
Nor should the architect of this great victory be forgotten. The Byzantine historian Vasiliev concludes that “by his successful resistance Leo saved not only the Byzantine Empire and the Eastern Christian world, but also all of Western civilization.”
Yet, true to the vicissitudes and ironies of Byzantine history — the word has not come to mean “convoluted” for nothing — by the time Leo died, “in the Orthodox histories he was represented as little better than a Saracen” (hence the famous appellation, “Leo the Heretic”) owing to the Iconoclastic controversy. If Charles Martel would be memorialized as the heroic grandfather of the first Holy Roman Emperor, Charlemagne, it would be Leo’s lot to be all but anathematized — an unfortunate fact contributing to the historical neglect of this brilliant victory.
— Raymond Ibrahim is author of Crucified Again: Exposing Islam’s New War on Christians.