 The Umayyads decisively defeated the Byzantines at the Battle of Sebastopolis in 692 and parried a Byzantine counter-attack in 693/94 in the direction of Antioch.Over the following years, the Umayyads launched constant raids against the Byzantine territories in Anatolia and Armenia, led by the caliph's brother Muhammad, and his sons al-Walid, Abd Allah, and Maslama, laying the foundation for further conquests in these areas under Abd al-Malik's successors, which would culminate in the Second Arab Siege of Constantinople in 717–718.The military defeats inflicted on Justinian II contributed to the downfall of the emperor and his Heraclian dynasty in 695, ushering in a 22-year period of instability, in which the Byzantine throne changed hands seven times in violent revolutions, further aiding the Arab advance.