Second Arab Siege of Constantinople

In 717 AD, the Umayyad Caliphate launched a massive land and sea assault on Constantinople, determined to capture the city once and for all. A huge army under the general Maslama, brother of Caliph Sulayman, crossed into Thrace and surrounded the land walls, while a great fleet blockaded the city by sea. The new emperor Leo III, who had seized the throne only months earlier, organized a determined defense. The Theodosian Walls resisted all assaults, and Byzantine ships using Greek fire destroyed much of the Arab fleet. The besiegers then suffered a terrible winter of heavy snow. Famine and disease spread through their camp, and they were forced to eat their animals. Reinforcements from Egypt were betrayed by Christian crewmen who defected to the Byzantines. The Bulgarians, allied with Leo, also attacked the Arab army. In August 718 AD, the new caliph ordered the siege lifted. The retreat was a disaster, with more ships lost to storms. The failure ended serious Arab attempts to take Constantinople and helped protect Europe from further expansion from the east.