Fall of Constantinople Marks End of Byzantine Empire

The Ottoman siege of Constantinople in 1453 ended the Byzantine Empire, which at that point existed only around the capital and a few outlying areas. Internal religious divisions and the empire's weakened state prompted Emperor Constantine Palaiologos to appeal to Pope Nicholas V for aid. The Pope sent Cardinal Isidore and Archbishop Leonardo of Mytilene, whose presence sparked popular anti‑Latin protests in the city.

Sultan Mehmed II assembled an army of about 150,000 men and a fleet of 400 ships, equipped with a large cannon made by Saxon craftsmen. On 7 April he established a camp before the Gate of St Romanus and formally began the siege. The Byzantines could field roughly 7,000 defenders, including 2,000 mercenaries mainly from Venice and Genoa, while about 50,000 civilians faced severe food shortages. The city's double walls, which had protected it for a millennium, were subjected to daily cannon fire from 12 April onward.

Ottoman forces repeatedly tried to breach the chain protecting the Golden Horn. On 20 April a supply flotilla under the commander Flanternella succeeded in breaking the chain after a fierce naval battle, briefly relieving the besieged. Recognizing that artillery alone could not capture the city, Mehmed sought additional tactics to overcome the remaining defenses.