The siege of Constantinople in 717-718 is often overlooked. Although it was much less significant, it seems that the Battle of Tours in 732 is better remembered.
And Islam has not changed its goals or its methods.
The West could use another leader like Emperor Leo III, the hero of Constantinople in 717-718.
Delivery for Constantinople came from the least expected source: the Egyptian crew manning the Alexandrian ships, the Christian Copts. Because the vast majority of the caliphate’s fighting men, the mujahidin, were already engaging the enemy, the caliph had no choice but to rely on Christian dhimmi (second-class) conscripts for reinforcements. Much to the caliph’s chagrin, however, the Copts all fled at nighttime to Constantinople, and acclaimed the Christian emperor.