| 717-718 | Siege of Constantinople (2nd) | ★ ★ ★ ★ ★ |
| Outcome: | An unsuccessful siege of Constantinople and a disaster for the Arabs | 717-718 |
| War & Enemy: |
Enemy: Arabs (Umayyads)
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War: Early Byzantine-Muslim Wars
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Battle Type: Siege
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| The Battlefield | ![]() |
Location: Constantinople |
Modern Country: Turkey |
| The Byzantines(emperor: Leo III) | The Enemies | |
| Commander: | Emperor Leo III | Masalmas (Maslamah ibn Abd al-Malik) |
| Forces: | 30,000 + 50,000 Bulgarians (cavalry) | 80,000 to 120,000 + 2560 ships |
| Losses: | 2555 ships and almost the entire army |
| Background story: | After the first Arab siege of Constantinople (674-678), the Arabs decided a second decisive attack on the city. It was known that the Arabs had been preparing for years. Emperor Leo III had seized the throne from Anastasius II on 25th March 717. The latter was willing to abdicate, in part because he knew he was not in position to cope with this extremely serious Muslim threat. An 80,000-strong army led by Maslamas crossed the Bosporus from Anatolia to besiege Constantinople by land, while a massive fleet of Arab war galleys commanded by admiral Suleiman, with 1,800 ships, sailed into the Sea of Marmara to the south of the city. The Byzantines had been well prepared though. In addition, they had a valuable ally: the Bulgars. The Bulgars, who had established friendlier relations with the Byzantines a year earlier under Khan Tervel, on the face of the looming Arab threat, came to the aid of the besieged city in the fall of 717. Norwich states "The Bulgars had no love for the Byzantines, but they preferred them to the infidel and were in any case determined that, if Constantinople were to be taken, it should fall into Bulgar rather than Arab hands". The Bulgars were to play a decisive role in the battle. |
| The Battle: | ![]() An Egyptian fleet of 400 ships and an African fleet of 360 ships arrived in the spring with fresh reinforcements, but successive assaults on the city were unable to cause a breach in its defenses. Moreover, many of the sailors who manned the Arab fleet were Christian slaves who found the opportunity to desert en masse. In the fall of 717 the Bulgars started their attacks on the West side of Bosporus. The Arabs were surprised by the new enemy whose attack on their own camp, was followed by a horrible massacre. Encouraged by this, the Byzantines opened the gates and attempted to break the siege, but were stopped at the Arab trenches and had to retreat. This scene was repeated several times during the siege with the same ill success for both sides. The constant Bulgar attacks in the rear of the Arabs forced them to build trenches also against the Bulgars. This way, however, the Arabs found themselves in a thin line between two fortifications, which was under attack on both sides. After an unusually harsh winter, weary from the long attrition of siege warfare, thinned out by disease and hunger, and demoralized by the lack of success in assaulting the city, the Arabs attempted to retreat to their ships in July, but were devastated by a Bulgar attack against their land forces. Contemporary chroniclers report that at least 22,000-32,000 Arabs died in that Bulgarian attack. Unable to continue the siege under these circumstances, the Arabs were forced to abandon their ambitions on Constantinople in August. Part of the Arab army attempted to withdraw back through Anatolia while the rest attempted to withdraw by sea in the remaining Arab vessels. A devastating storm wrecked the Arab fleet on its way back, destroying all but five galleys and drowning all the men onboard. |
| Noteworthy: | |
| Aftermath: | It was a severe blow for the Arabs and a pivotal event that turned back the tide of Muslim incursions into Europe. |
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