15 August 718 – Siege of Constantinople ends
“The Arab attacks would in any case have intensified after the end of their own civil war. With far more men, land and wealth than Byzantium, the Arabs had begun to concentrate all their strength against it. Now they threatened to extinguish the empire entirely by capturing its capital.” (Warren Treadgold)
“The new Caliph swore to not stop fighting against Constantinople before having exhausted the country of the Arabs or to have taken the city.” (EW Brooks)
“Had a victorious Caliph made Constantinople already at the beginning of the Middle Ages into the political capital of Islam, as happened at the end of the Middle Ages by the Ottomans, the consequences for Christian Europe would have been incalculable.” (Edward Gibbon)
When the Western Roman Empire had finally limped out of existence with the abdication of Romulus Augustulus in Ravenna in 476 AD, the eastern empire had continued. The emperor in Constantinople looked well placed to succeed where his counterparts in the west had failed, having not had that fraught time of increasingly forfeiting a reduced territory for the migrating Germanic tribes to settle on and thus seeing Roman lands become Gothic, Vadal, Frankish, Burgundian, and more. While the Rhine and Danube had been porous frontiers, the east had been protected by the Euxine (Black) Sea, the relative stability of the Euphrates and Armenian border with the settled power of Sassanid Persia, and the wastes of the Sahara and Arabia.
A restoration looked on in the Sixth Century when Justinian’s general Belisarius restored Roman control over Italy to drive the Goths out, destroyed the Vandal state to recapture Carthage and Africa, and even controlled much of the southern Spanish coast. That time was followed by a devastating plague which crippled the populace and the economy, followed by a huge invasion by the Sassanids always seeking to restore the halcyon days of Achaemenid Persia which had stretched from India to the Balkans. While Heraclius had managed to drive them out, this exhausting campaign – part of the third longest-running war in human history – had left both sides ill prepared for what was to come. For a new power was rising in the desert, with a new prophet spreading news of a growing religion. His name was Mohammed.
The meteoric rise of Islam in the Seventh Century was made possible by the events that preceded it. The Arabs had always been seen as a disparate collection of tribes posing no threat to the settled societies of Rome and Persia – a fatal mistake the Chinese would make with the Mongols half a millennium later. They exploded out of the desert with a series of successes under the new tribal coalition that defeated the Byzantines at Yarmuk and then the Sassanids at al-Qādisiyyah, ending the longest enduring Persian empire in just six years. As with all successful empires though it soon fell to civil strife, with the First Fitna seeing the Rashudin Caliphate replaced by the Umayyads as they established the largest of the Muslim empires, stretching from Spain into central Asia.
Byzantine Emperor Leo the Isaurian had risen to the purple at a time of turmoil known as the Twenty Year Anarchy, initially being sponsored by the Muslims to continue this disorder and using that patronage to instead turn on them once securing his position in Constantinople. The Byzantines had used the Second Fitna as an opportunity to force tribute from Damascus, though the failure of Justinian II’s renewed offensives saw the Arabs regain control of Armenia and the Caucuses, then gradually push into Roman territory as the defensive systems began to collapse. The Twenty Year Anarchy merely emboldened the Arabs further to push west through Asia Minor, in addition to their westward expansion along the north African coast.
The Caliph Sulayman took confidence from a prophecy that a leader bearing his name would capture Constantinople, and he was the only one with that name in the imperial family. The Arabs began assembling a large fleet and army while simultaneously expanding into India, central Asia, and the Iberian Peninsula. The former emperor Anastasios II had begun rejuvenating the fleet and preparing the walls for the imminent siege, and his successor would reap the dividends of the preparedness. The Byzantines were at a huge advantage given by the Theodosian Wall of Constantinople. These indomitable fortifications had been built in the late Fourth Century by the last ruler of a united Roman Empire, and while there were marauding bands of Goths and Huns, such infrastructure was hardly required at the time, although the resources were plenty. Now that the infrastructure was required, the resources were scarce. If these walls had not already been in place, the Byzantines would have been unable to affect the resistance they did in times of siege, and Constantinople would not have persevered for as long as it did.
The Muslims gradually advanced throughout the years of Byzantine civil war, and initially they saw Leo as an alley to prolong the internal strife. The fortress of Amorium was offered terms of surrender to recognise him as emperor, though the gates remained shut, and when Leo arrived with a small force he used a series of ruses to trick the Arabs into thinking he had a large army, and forced them to retreat. The main Arab army was still on the march, crossing the Taurus Mountains while not devastating the area as they still believed Leo to essentially be a puppet ruler. They learnt of his victory during the retreat of the advance party, and changed direction to attack Akroinon, then making for the coast to sack Sardis and Pergamon. This was all done to the backdrop of Leo’s own march on Constantinople which would see him crowned.
The Arab army numbered between 120,000 and 200,000 men, with close to 2,000 ships in support, and a huge supply chain of 12,000 men, 6,000 camels and 6,000 donkeys providing provisions that had been hoarded to cover several years. The Byzantine garrison defending Constantinople likely numbered less than 15,000. In early summer of 717, the Muslim commander Maslama ordered his fleet to join him as he led the army across the Hellespont (Dardanelles) at Abydos into Thrace. The army devastated the country and sacked towns as they marched, gathering supplies as they isolated Constantinople. They built a double siege wall, one side facing the city and the other the countryside – just as Julius Caesar had done all those centuries ago at Alesia – with the camp in-between, and Leo proffered a ransom of a gold coin for every inhabitant. Maslama replied that there could be no peace with the vanquished, and he had already selected his Arab garrison for the city.
The Arab fleet anchored in the Bosporus and began blockading the city suburbs in both Europe and Asia, guarding both entrances to the strait to prevent naval communication for the Byzantines from either the Mediterranean or the Euxine Sea. As the rearguard of 20 ships passed close to the city a southerly wind reversed them towards the walls, where a Byzantine squadron attacked them with the devastating Greek fire. This victory encouraged the Byzantines while disheartening the Arabs, who had hoped to sail up to the sea walls at night and scale them. That night Leo drew up the great chain between the city and Galata, closing the entrance to the Golden Horn. The fleet was reluctant to engage the Byzantines, so withdrew to safe harbor further north.
The Muslim army was still well supplied, even having wheat to sow for the following year’s harvest, though the naval failure meant fresh supplies could no longer be ferried across, while the previous devastation of the surrounding lands hampered the success of foraging. Negotiations began in the winter, with sources differing as to whether Leo tricked Maslama into handing over their grain or whether the Muslim leader had it burnt so the citizens could see there would be no relief. The Winter entering 718 was harsh, with three months of snow, and famine drove the Muslims to eat their horses as supplies ran out. Bark, leaves, tree roots, camels, and horses were all on the menu, and some sources report cannibalism and eating of excrement. This was compounded by epidemics ravaging the army, with some far-fetched sources recording deaths from disease as high as 300,000 men.
The new Caliph Umar II looked to improve the situation when two fleets came to boost the besiegers, with 400 from Egypt and 360 from Africa, while a fresh army began marching across Asia Minor. The new fleets anchored some distance from Constantinople, though many of the Christian Egyptians among both crews swiftly began deserting to the city. Learning from these deserters about the new fleets’ positions and composition, Leo was emboldened to launch a fresh attack against the beleaguered crews. Crippled by the desertions and helpless against Greek fire, the Arab fleets were destroyed or captured along with their weapons and supplies, securing the city from a naval attack. On land the Byzantines managed to ambush the advancing Arab support army and destroy it around Sophon, south of Nicomedia.
The tables had turned, and now Constantinople could be easily resupplied by sea and fishermen could return to work. Muslim woes were compounded with a further defeat against the Bulgars in which 22,000 men were killed. They may have been no friend of the Romans, but the Bulgars had seen their country devastated by the marching Muslims and knew this army was no friend of theirs, so seized the chance to attack their weakened and demoralized enemy. The siege had clearly failed, and orders were sent for Maslama to retreat. After 13 months, on 15 August 718, the Arabs departed. The retreat came on the same day of the feast of the Dormition of the Theotokos (Assumption of Mary), and the Romans ascribed their victory to the mother of Christ. The retreating army was not harassed, though the fleet lost a great number of ships in a storm in the Marmara Sea, while others were set ablaze from the ashes of the volcano of Santorini, and some sources claim only ships made it back to Syria. Arab sources state that around 150,000 of their soldiers died in the failed siege – another disaster for the caliphate. Victory for the Byzantines afforded Leo a time of peace on the eastern front and an opportunity to consolidate his power, bringing much needed stability to the beleaguered empire.
The Muslim desire for expansion still remained though, and the next concerted effort to extend the boundaries into the old Roman world would come in the west, where their armies would push through Iberia and into Frankia, a divided land that Charles Martel was still fighting to unify, but would manage to summon the forces to smash the Umayyad behemoth at Tours. The next Fitna saw the Abbasids focus east rather than west, with their capital at Baghdad, and confrontation betwixt Islam and Byzantium reduced. The rise of the Seljuk Turks in the Eleventh Century would rekindle that enmity, with the Byzantines smashed at Manzikert before they failed to fully support the First Crusade and thus saw its conquests become independent kingdoms rather than Roman lands again. Antagonism would grow between Catholic Rome and Orthodox Constantinople, culminating in the Fourth Crusade sacking the city of Constantine in 1204 to pay off their debts to the Venetians after becoming embroiled in a succession dispute. The Eastern Empire would never fully recover, though it would continue until it finally fell to the Ottoman Empire under Mehmet the Conqueror in 1453.
Written by Jack Tappin
15 August 718 – Siege of Constantinople ends