On may 29 1453, the Ottoman cannons broke through of Constantinople's Theodosian walls and Sultan Mehmed the second Ottoman armies swarmed into Constantinople, overwhelming the 7,000 Greek Byzantine and Italian soldiers who were defending it, and conquered the city.
For over 1,000 years the "impregnable" Theodosian walls of Constantinople had defended the eastern capital of the Roman empire (which was later called the Byzantium empire) from every foe that tried to conquer it.
The imperial capital dedicated by Constantine I in 330 had resisted siege on numerous occasions. The triple line of fortifications constructed on the land side in the fifth century by Constantine the Great had held off attacks by Goths, Persians, Avars, Bulgars, Russians, and especially Arabs. Even today they make an impressive sight.
That is until a certain 21year old Ottoman Turk by the name of Sultan Mehmed II decided to have a go at them at 1453, succeded, turned Constantinople into present day Istanbul and changed the course of world history.
The famed Theodosian walls.
In many respects the city of Constantinople which had for so long eluded the Arabs and Turks was no longer the great Queen of Cities it had once been.
That city had already been destroyed in 1204 by Western forces of the Fourth Crusade who had plundered its wealth and then occupied it for 57 years. When the Byzantines reconquered their capital in 1261, they attempted to restore its past glory but could never recreate its former strength.
However for the Ottomans it was the ultimate prize, the capital of their most hated enemies, and a city that resisted Ottoman attacks many times in the past and seemed almost unconquerable to them.
As the Ottomans closed in on their prize, Constantinople became the last outpost of Christian faith in the Middle East, and its inhabitants had to face their historic destiny.
Mehmed II and the Ottoman Army approaching Constantinople with a giant bombard, by Fausto Zonaro
The capture of Constantinople (and two other Byzantine splinter territories soon thereafter) marked the end of the Roman Empire, an imperial state that had lasted for nearly 1,500 years.
The last Byzantine emperor, Constantine XI Dragases Palaiologos, was killed in the battles and subsequently became the last Roman emperor in history. The church of Hagia Sophia, one of christendom's most ancient, important and holy religious sites, became a mosque.
The Ottoman conquest of Constantinople also dealt a massive blow to Christendom, as the Muslim Ottoman armies thereafter were left unchecked to advance into Europe without an adversary to their rear.
After the conquest, Sultan Mehmed II transferred the capital of the Ottoman Empire from Edirne to Constantinople.
A reconstruction of how Constantinople used to look like before the Ottoman conquest.
The conquest of Constantinople was a pivotal moment in world history, because it marked the final death of the ancient Byzantine empire, and of the ancient world, and the birth of a new world with a new empire that would dominate not just the middle east, but also the mediterranean, Arabia, North Africa and large parts of Europe for the coming the centuries.
That new empire was the Ottoman empire.
The Ottoman empire became one of the largest empires that ever existed, and at its peak it stretched from central Europe to the horn of Africa, and its impact on the world's history and culture can be felt even today.