second Arab civil war was raging in Arabia and Syria resulting in a series of four caliphs between the death of Muawiyah in 680 and the ascension of Abd al-Malik in 685, and was ongoing until 692 with the death of the rebel leader. The Saracen Wars of Justinian II (r. 685–695 and 705–711), last emperor of the Heraclian Dynasty, "reflected the general chaos of the age". After a successful campaign he made a truce with the Arabs, agreeing on joint possession of Armenia, Iberia and Cyprus; however, by removing 12,000 Christian Mardaites from their native Lebanon, he removed a major obstacle for the Arabs in Syria, and in 692, after the disastrous Battle of Sebastopolis, the Muslims invaded and conquered all of Armenia. Deposed in 695, with Carthage lost in 698, Justinian returned to power from 705 to 711. His second reign was marked by Arab victories in Asia Minor and civil unrest. Reportedly, he ordered his guards to execute the only unit that had not deserted him after one battle, to prevent their desertion in the next. Justinian's first and second depositions were followed by internal disorder, with successive revolts and emperors lacking legitimacy or support. In this climate, the Umayyads consolidated their control of Armenia and Cilicia, and began preparing a renewed offensive against Constantinople. In Byzantium, the general Leo the Isaurian (r. 717–741) had just seized the throne in March 717, when the massive Muslim army under the famed Umayyad prince and general Maslama ibn Abd al-Malik began moving towards the imperial capital. The Caliphate's army and navy, led by Maslama, numbered some 120,000 men and 1,800 ships according to the sources. Whatever the real number, it was a huge force, far larger than the imperial army. Thankfully for Leo and the Empire, the capital's sea walls had recently been repaired and strengthened. In addition, the emperor concluded an alliance with the Bulgar khan Tervel, who agreed to harass the invaders' rear. From July 717 to August 718, the city was besieged by land and sea by the Muslims, who built an extensive double line of circumvallation and contravallation on the landward side, isolating the capital. Their attempt to complete the blockade by sea however failed when the Byzantine navy employed Greek fire against them; the Arab fleet kept well off the city walls, leaving Constantinople's supply routes open. Forced to extend the siege into winter,