1. Constantinople (1453)
A series of incompetent rulers, the effect of the Fourth Crusade, which stopped in Constantinople rather than Jerusalem, and an ever-encroaching Ottoman Empire had weakened the once-mighty Byzantine Empire. It was once regarded as an heir to the glorious Roman Empire - the remaining force after their demise - and Istanbul, as it's now known, was the greatest city in the world. In the early 1300s, Anatolia had been divided into independent states. One of the local leaders, Osman, from whom the Ottoman name derives, soon began extending their frontiers and encroaching on Byzantine land. The Ottomans soon had the Byzantine Empire surrounded, winning battles at Kosovo and Nicopolis, and it became obvious Constantinople was only a matter of time. Constantinople was believed to be impregnable, but, with only 8,000 troops defending the entire city, Constantine XI the first Constantine being the Roman Emperor who made it the capital of his empire and began its ascension had an almost impossible task on his hands. Mehmed II, on the other hand, had between 75,000 and 100,000 troops and a large fleet. The preparation on the Ottoman side is legendary. First, a castle was built on the Bosphorus, stopping any potential relief attempts getting close to the city. Secondly, a Hungarian artillery expert was hired to build the world's biggest cannon to bring down those sturdy walls. Finally, and most impressively, because a river-wide chain blocked entry to the Golden Horn, the Ottomans dragged their ships, using logs, over land and into the Golden Horn. The first assaults provided little success, with the Ottomans making heavy losses. Mehmed II, not a particularly patient man, ordered a final assault from sea and land, which overcame the attackers. Constantine XI was killed during a last charge and Mehmed II entered Constantinople on a white horse, before praying at the Hagia Sofia, the city's iconic cathedral. Despite the Great Schism a Roman Catholic/Orthodox argument that led to the Fourth Crusade's actions Christian Europe was shook by the news. The Pope ordered a crusade to drive back the Muslims, but it received no reaction. The Ottoman Empire, on the other hand, was eager to attack mainland Europe. The Byzantine Empire had come to an unceremonious end.