The Ottoman Turks captured Constantinople in 1453, ending the Byzantine Empire.
Sultan Mehmed II's Ottoman army began its siege on 6 April 1453. The city was defended by Byzantine Emperor Constantine XI Palaiologos and a small force of Byzantine and foreign soldiers. After 53 days, the Ottomans broke through the city's defenses and captured Constantinople on 29 May.
A decisive factor was Ottoman artillery, including enormous bombards capable of damaging the famous Theodosian Walls. Those walls had protected the city from major attacks for centuries, but concentrated cannon fire, infantry assaults, and the defenders' limited manpower eventually overwhelmed them. Mehmed entered the city and later made it the Ottoman capital, replacing Adrianople.
The conquest ended the Byzantine Empire, although Byzantine successor states had survived after the Fourth Crusade's capture of Constantinople in 1204. It also ended the Roman imperial state in the East, which had continued for nearly 1,500 years. The fall is often treated as a turning point between the Middle Ages and the early modern period, though historians debate that boundary.