Byzantine Empire
Umayyad Caliphate launched the siege of Constantinople
Constantinople, Byzantine Empire
In 717 the Umayyad Caliphate launched the siege of Constantinople (717–718) which lasted for one year. However, the combination of Leo III the Isaurian's military genius, the Byzantines' use of Greek Fire, cold winter in 717–718, and Byzantine diplomacy with the Khan Tervel of Bulgaria resulted in a Byzantine victory.