The Second Arab Siege of Constantinople was a critical military engagement during the early stages of the Arab-Byzantine wars, a series of conflicts that shaped the boundaries and relationships of the Mediterranean region. In 718, the Umayyad Caliphate, which had rapidly expanded its territories through military conquests, turned its attention to the Byzantine capital. Under the leadership of Caliph Al-Walid I, the Muslim forces sought to capture Constantinople to establish Islamic control over the region and to secure trade routes. The siege combined a formidable army that included troops from various parts of the Caliphate, highlighting the extensive reach of Islamic military forces.The defense of Constantinople was orchestrated by Leo, a capable military commander who would become Emperor Leo III. The city was protected by the Theodosian Walls, famous for their strength, which had previously thwarted several attempts to breach the city. During the siege, the Byzantines employed innovative tactics, including utilizing Greek fire, a devastating incendiary weapon, to repel the attackers. The prolonged assault by the Umayyads faced logistical challenges, as well as a steadfast defensive strategy led by Leo, which ultimately culminated in the Arab forces lifting the siege after several months. This marked a significant turning point as it halted the rapid Muslim expansion into Europe and fortified the Byzantine position for years to come.