The Fall of Constantinople the capital of the Byzantine Empire, which occurred after a 53 day siege by the Ottoman Empire, under the command of Sultan Mehmed II with an army of 100,000 and 320 ships, against the defending army of 5,000 Greeks and 2,000 mercenaries, commanded by Byzantine Emperor Constantine XI.
The siege lasted from Friday, April 6, 1453 until Tuesday, May 29, 1453, when the city was conquered by the Ottomans. The Fall of Constantinople was not the end of the final remnant of the Roman Empire. In 1472, Constantine's niece went to Moscow and married Ivan III, Grand Duke of Moscow and the Imperial court and coat of arms was transfered to Moscow and Ivan took the title of Caesar (Tsar).
On the 45th day of the siege, the sultan sent an ambassador to Constantine. He asked for the surrender of the city, on the promise that he would allow Constantine, the defending army and any other inhabitant to leave with full honor and their property. Constantine would become prince of Morea, an Ottoman vassal state in Greece. Lastly, he would guarantee the freedom, safety and property of the population that would remain in the city. Constantine refused the offer.
Upon entering the city on May 29th 1453, Mehmed II sent in an advance guard to protect key buildings. The advance guard fanned out along the main thoroughfare of the city, by the great forums, by the great church Hagia Sophia and by the Church of the Holy Apostles, which Mehmed II wanted to be the seat for his newly appointed Orthodox Patriarch of Constantinople. Although he made the great church Hagia Sophia into a mosque, Mehmed declared that the Church of the Holy Apostles would remain a Christian Church forever.
Byzantine historian George Sphrantzes was an eyewitness to the fall of Constantinople. In his chronicle about the fall of the city. Here is what he wrote down about the events that took place on the third day of the conquest.
"On the third day after the fall of our city, the Sultan celebrated his victory with a great, joyful triumph. He issued a proclamation: that the battle was over and citizens of all ages who had managed to escape capture were to leave their hiding places throughout the city and come out into the open, as they would remain free and no questions would be asked of them. He further declared the restoration of houses and property of those who had abandoned the city before the siege, if they returned home, they would be treated, as if nothing had changed."
The Byzantine Empire suffered 4,000 killed, defenders and civilians, the Turkish army suffured 10 times the losses of the defenders; but in the end the walls could not withstand months of steady bombardment by huge cannons.
After the conquest Mehmed made Constantinople the Ottoman Empire's new capital. Some historians mark the end of the Middle Ages by the fall of the city and the Byzantine Empire.
Mehmed founded many universities and colleges in Constantinople, some of which are still active to this day. Mehmed II is also recognized as the first Sultan to codify criminal, civil and constitutional law.
In 1930 the Republic of Turkey officially changed the name of the city to Istanbul.