Maslama ibn Abd al-Malik
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.