The Fall of Constantinople (, ; Conquest of Istanbul) was the capture of the capital of the Eastern Roman (Byzantine) Empire by an invading army of the Ottoman Empire on Tuesday, 29 May 1453. The Ottomans were commanded by 21-year-old Ottoman Sultan Mehmed II, who defeated an army commanded by Byzantine Emperor Constantine XI Palaiologos. The conquest of Constantinople followed a seven-week siege that had begun on Friday, 6 April 1453. The capture of Constantinople (and two other Byzantine splinter territories soon thereafter) marked the end of the Roman Empire, an imperial state which had lasted for nearly 1,500 years. The Ottoman conquest of Constantinople also dealt a massive blow to Christendom, as the Ottoman armies thereafter were free to advance into Europe without an adversary to their rear. After the conquest, Sultan Mehmed transferred the capital of the Ottoman Empire from Edirne to Constantinople. Several Greek and non-Greek intellectuals fled the city before and after the siege, with the majority of them migrating particularly to Italy, which helped fuel the Renaissance. The conquest of the city of Constantinople and the end of the Byzantine Empire was a key event in the Late Middle Ages which also marks, for some historians, the end of the Middle Ages.