The Fall of Constantinople

The Fall of Constantinople was the capture of the capital of the Byzantine Empire, which occurred after a siege by the Ottoman Empire, under the command of Sultan Mehmed II, against the defending army commanded by Emperor Constantine XI. The siege lasted from Friday, 6 April 1453 until Tuesday, 29 May 1453 (according to the Julian Calendar), when the city was conquered by the Ottomans.
The Fall of Constantinople marked the end of the Roman Empire, an empire which had lasted for over 2,200 years, and was a massive blow for Christendom. After the conquest Mehmed made Constantinople the Ottoman Empire's new capital. Several Greek and non-Greek intellectuals fled the city before and after the siege, migrating particularly to Italy. It is argued that they helped fuel the Renaissance. Some mark the end of the Middle Ages by the fall of the city and empire.[
On the third day after the fall of our city, the Sultan celebrated his victory with a great, joyful triumph. He issued a proclamation: the citizens of all ages who had managed to escape detection were to leave their hiding places throughout the city and come out into the open, as they were remain free and no question would be asked. He further declared the restoration of houses and property to those who had abandoned our city before the siege, if they returned home, they would be treated according to their rank and religion, as if nothing had changed.
—George Sphrantzes
The loss of the city was a massive blow to Christendom; the Pope called for an immediate counter-attack in the form of a crusade, but when no European monarch was willing to lead the crusade, the Pope himself decided to go; his early death eliminated the possibility of a counter-attack.
With Constantinople beneath his belt, Mehmed II had acquired a great, rich city albeit one in decline due to years of war. The Capital allowed the Turks to establish a permanent supply base in Christian Europe. Further advances into Hungary and the principalities...