After several failed sieges against the seat of the Eastern Roman Empire, in the year 715, the Umayyad caliphate concluded that enough was enough: it would vomit forth all it had in one final, all-out effort to conquer the ancient Christian capital.

Caliph Suleiman summoned his younger brother, Maslama, and commanded him to lead Islam’s combined forces to Constantinople and “stay there until you conquer it or I recall you.” The young emir embraced the honor: “I [will] enter this city,” proclaimed he, “knowing that it is the capital of Christianity and its glory; my only purpose in entering it is to uphold Islam and humiliate unbelief.”

At the head of 120,000 Muslim fighters, Maslama crossed into Christian territory and, with “both sword and fire, he put an end to Asia Minor,” wrote a near contemporary chronicler. On August 15, 717, he began bombarding the city, which was defended by Leo III, formerly a general. Just weeks earlier, and because he was deemed the ablest man, Leo had been consecrated in the Hagia Sophia Cathedral as new emperor.

Unable to breach the cyclopean walls of Constantinople, Maslama waited for 1,800 vessels containing an additional 80,000 fighting men to approach through the Bosporus and completely blockade—and thus starve—the city.

Suddenly Leo ordered the ponderous chain that normally guarded the harbor cast aside. Then, “while they [Muslim fleets] hesitated whether they should seize the opportunity . . . the ministers of destruction were at hand.”

Leo had sent forth the “fire-bearing ships” against the Islamic fleet, which was quickly set “on fire,” writes Theophanes the chronicler: “some of them were cast up burning by the sea walls, others sank to the bottom with their crews, and others were swept down flaming.”