On this day in 717, the Byzantine Navy managed to defeat the thousands ships strong Muslim Armada, through the use of Greek Fire. The Byzantines were at the time under siege in Constantinople, where the Umayyad Caliphate was using a combination of land and sea troops to attempt to seize control over the city. The Caliphate sought to do this while Byzantium was weak, as there was significant internal strife in Byzantium at the time, with a rebellion to place Leo III on the throne, and overthrow Theodosius III. The Muslim army was blockading Constantinople by the fall, limiting the amount of resources it could receive, and causing disruption within the city. Using Greek Fire, a secret Byzantine weapon that could burn on water and thus gave them a tremendous advantage over other navies, the Byzantines were able to win the battle. The Caliphate, discouraged by the defeat and ravaged over the following winter by famine and disease, retreated in 718, and would not return to Constantinople for centuries. The end of the battle also saw the end of the blockade, and the victory would ensure Byzantium’s independence and safety from the Muslim invasions for the next centuries. The battle also caused a change of Umayyad strategies, and is credited with delaying the Muslim invasions of Eastern Europe and parts of Asia until the rise of the Ottoman Empire and the fall of Byzantium in the 15th century.