The Last Bastion of Europe

The epic struggle between East and West, the Umayyad Caliphate and the Byzantine Empire during the Siege of Constantinople.
The view across the Golden Horn
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400 years before the First Crusade, Christianity was on its knees before an ascendant Muslim Caliphate.

Yet only 80 years before that, in AD629, the late Roman Emperor Heraclius had staged a grandiose ceremony in the city of Jerusalem to mark the Empire’s final and emphatic victory over its long-standing rival, the Persian Empire. The high point of the triumphal procession was the restoration of the “True Cross” to its rightful place. The relic had been taken from Jerusalem by Khosrow II in AD614 and carried off to distant Ctesiphon, a sign of Persian dominance over wilting Roman power. But through a brutal and brilliant campaign, Heraclius had achieved what no other Roman Emperor could: a final and resounding victory over the Persians from which there was no coming back. The annexed provinces of Egypt, Palestine and Syria were restored to the Eastern Roman Empire, and the Emperor and his realm could look forward to a period of much needed respite from near constant war.

However, unknown to Heraclius, even as he acknowledged the acclaim of the crowds in the streets of Jerusalem, an obscure prophet named Muhammad had successfully united the many disparate Arab tribes dwelling on the peripheries of the Empire and throughout the Arabian Peninsula. Animated by the new spiritual force of Islam, this growing army of Muslim warriors would ensure that Heraclius never got his well-earned rest. Instead, the first action fought between Muslim and Roman (or Byzantine) forces was the Battle of Mu’tah in September AD629. Although that was a tactical victory for the Byzantines, the inexorable rise of Islam had begun.

The Umayyad Caliphate, 750AD. Image: Ergovius, Wikicommons

By the time of Heraclius’ death, the restored provinces of the Levant and Egypt had once more fallen into enemy hands. He died in despair, a broken and disappointed man. By then, the armies of Islam had assumed the glamour of an unstoppable force. The dying Persian Empire fell easily into their hands. Everywhere, the Byzantines were on the back foot, ceding Syria and the islands of Rhodes and Crete, and pushed back from their frontiers deep into the Anatolian plateau. Meanwhile, Islam’s fervid forces, under the impassioned leadership of warrior-prophets like Umar, had fallen under the control of a single dynasty: the Ummayyads, the first to style themselves Caliphs, which means successors. (To Muhammad, naturally.)

Perhaps the most powerful of these was Mua’wiya, who had emerged victorious from the First Muslim Civil War in AD661. Mua’wiya was determined to establish dynastic, hereditary rule within this one clan, seating the capital of their burgeoning empire in the ancient city of Damascus. From there, the Muslim conquests continued with remarkable success, swallowing Transoxiana, Sindh, the Maghreb, and in time the Iberian Peninsula, thus making the Ummayyad Caliphate one of the largest empires in history.

But amid that expansion, Mua’wiya’s boldest move was the attempt to decapitate the beleaguered Roman/Byzantine Empire once and for all. In AD674, he mounted a concerted assault on the city of Constantinople. Having secured bases along the coast of Asia Minor, he set about installing a blockade around the Great City. Using the nearby peninsula of Cyzicus as a base to spend the winter, he returned every spring for five years to launch attacks on the city’s fortifications.

However, Mua’wiya hadn’t reckoned on the Great City’s defences. On its landward side stood the Walls of Theodosios, a massive three-tiered system of stone fortifications constructed in the 4th century, which had proved impregnable ever since. On the seaward side, facing the Sea of Marmara and the Bosporos Straits, the city was more vulnerable and might have succumbed were it not for a new secret weapon which the Byzantines now possessed. Greek Fire as it became widely known – or simply hydron pyr (liquid fire) as the Byzantines knew it – was the invention of a Syriac Jew called Kallinikos. As lethal and effective as it was terrifying to face, the Muslim ships could not withstand it. Each year they were forced to retire and the city still stood.

When Mua’wiya finally conceded failure and withdrew, the Byzantine Emperor Constantine IV was hailed as saviour of the city. Down certainly, but not yet out, the Empire would live to fight on. However, it wasn’t long before the Byzantines’ own line of imperial succession fell into disarray. The so-called ‘Twenty Years’ Anarchy arose out of opposition to the rule of Constantine IV’s son, Justinian II, whose increasingly despotic reign led to his deposition from the throne – not to mention the removal of his nose – by Leontios, a popular general. For the next 20 years, the imperial raiment was to change hands no fewer than seven times.

Sensing weakness, the Caliphate mobilised its forces for a second assault. This time there would be no question. The Arab armies would deploy a combined land and naval force of such overwhelming scale that the Byzantines couldn’t hope to hold out. Providence, the Muslims believed, was on their side. In Damascus, a prophesy had been proclaimed: that within 100 years after the Hijrah – Muhammad’s migration from Mecca to Medina – Allah would bring the whole world under his yoke. That date was fast approaching. It was surely obvious that this prophesy must refer to the final submission of the Christian Byzantine Empire to the divinely ordained Caliphate. The prophesy gave one further tantalising detail: that final victory would be achieved by a Caliph who shared a name with one of the Old Testament prophets. When it fell to Sulayman – whose name is the Arabic form of Solomon – to succeed his brother as Caliph, while preparations for the campaign were already underway, it seemed the enterprise was surely fated to succeed.

What’s more, the Arabs believed they had a man on the inside.

The Walls of Theodosios, these imposing walls proved impossible to overcome.

In AD716, Sulayman’s half-brother, Prince Maslama, a renowned general given overall command of the Muslim forces advancing on Constantinople, had forged a secret agreement with his Byzantine counterpart at a meeting shrouded in obscurity. Leo the Isaurian, at the time Strategos (governor-general) of the Anatolian army, had designs on the imperial crown. A deal was struck. Maslama would withdraw his troops to the south, and in return, Leo agreed to submit to the ultimate sovereignty of the Caliph, once he had removed the accountant-emperor Theodosios III from the throne.

Sure enough, Leo marched his army on Constantinople, declaring himself emperor and galvanising support for his claim along the way, not least by capturing the Emperor Theodosios’ son. When he arrived before the walls of Constantinople in March AD717, Theodosios was already persuaded to abdicate, and soon retired with his son into the seclusion of a monastery.

But Emperor Leo III was not what he appeared. A proven strategist, a consummate schemer, and a shrewd diplomatist, in fact he had deceived Maslama, thus clearing the way for himself to seize control. Now that he held the reins of power, Leo didn’t mean to give them up without a fight. He believed in the Empire and he readied the Great City for whatever the Arab armies meant to throw at it, filling the water cisterns to bursting, bringing the necessary food into the city to sustain its populace for several years, and of course stocking up on supplies of hydron pyr. Finally, he laid waste the city hinterland to the west and south to ensure that Maslama’s land forces had nothing to subsist on when they arrived to besiege the city.

Meanwhile, Maslama advanced with renewed intent to make Leo pay for his duplicity. With the Arab general marched an army of over 120,000 troops. In support at sea, a naval fleet of over 2000 warships was making its way north through the Hellespont and into the Sea of Marmara.

Maslama’s land forces cut off the city to the west in mid-August of AD717. The Arab fleet arrived on the first day of September.

Two chroniclers writing in the early 9th century, a Byzantine monk named Theophanes the Confessor and a later Patriarch Nikephoros I, provide us with substantial detail as to what happened next.

From the outset, things didn’t go well for the Arabs. As their massive fleet sailed into the Bosporos Straits in a brazen show of force, the wind suddenly changed, leaving the rearguard of the fleet becalmed at the mouth of the Golden Horn. Seizing their chance, Leo sent out a small fleet of dromons armed with the deadly syphons which then hosed down the Arab warships with liquid fire. The devastation was horrific. The rearguard was annihilated and the Arabs must have realised, all too late, that sheer numbers were still no match against a weapon of such unquenchable power.

Meanwhile, the Arab land forces under Maslama fared little better. As diplomatic missives and demands for the city’s capitulation flew between Leo and the Arab prince, the latter admonishing the Emperor for his shameful deception, the Muslims’ overwhelming numbers could make no dent on the unyielding stone walls of the city. Worse, news came from Damascus: the Caliph Sulayman had died from a sudden illness. Doubt crept in. Perhaps the hand of Providence had turned against the Arabs and the prophesy had been false?

As the weeks rolled on, winter settled over the siege, one of such biting cruelty as had not been witnessed in the Great City within living memory. Snow covered the ground for over 100 days, Theophanes recounts. The improbably brutal weather proved far more damaging to Maslama’s besieging armies than to the inhabitants of Constantinople, who remained sealed snugly behind their impenetrable fortifications. In the Arab camp, supplies ran low; hunger and death swiftly followed. The dead piled up and being unable to bury most of the bodies in the frozen ground, disease ran rife. Rumours abounded that the Arabs had been reduced to eating their own dung.

But Maslama was too proud simply to turn tail in the face of adversity. Instead, he sent word to his cousin, the new Caliph Umar II, to send a relief fleet bringing the food supplies his army so desperately needed. Umar, a mild man more interested in saving what was left of his armies than knocking out the Byzantine Empire once and for all, agreed to send the necessary support.

The arrival of the Muslim fleet in the spring, laden with wheat and reinforcements sent straight from Egypt, would be Maslama’s last roll of the dice to press on his grand project to victory. But, as the Chroniclers relate, the Emperor Leo had one or two more tricks up his sleeve…

Such is the historical centrepiece of my latest novel, A Burning Sea. The geopolitical stakes of this contest could hardly have been higher. Had the Arabs succeeded in turning Constantinople into a northern Islamic stronghold, little could have stopped their further expansion deep into the heartlands of Europe.

Thus, the siege’s eventual failure had far-ranging repercussions. While ensuring the continued survival of the Byzantine Empire, it caused the Caliphate to abandon its strategic goal of outright conquest. Indeed, the Arabs never made another attempt to knock out Constantinople. And no historian, ancient or modern, denies that the repulse of the Arab advance on the doorstep of mainland Europe marked a decisive moment in that continent’s history.

It’s worth adding that eventually Arab and Byzantine grew to accommodate one another, settling into an uneasy coexistence for the next few centuries. It took the encroachment of an outsider people – the Seljuk Turks – to upset this balance, once more stirring up animosity between the Christians and Muslims. In time, this would be answered by other outsiders, these from the Latin West, in the form of the first Crusaders.

But that’s for another story.

Theodore Brun is the author of The Wanderer Chronicles. The latest is A Burning Sea.

A Burning Sea