Fall of Constantinople

By the fifteenth century, the Byzantine Empire had contracted sharply, while Ottoman rule had expanded across much of Anatolia and the Balkans. Constantinople remained a major political and religious centre, positioned on the Bosporus between the Black Sea and the Mediterranean. Its location and massive land walls had long made it a strategically important city. The Ottomans, meanwhile, sought secure control of the approaches to the Bosporus and the surrounding region. In 1452, Sultan Mehmed II built the fortress later known as Rumelihisarı on the European shore of the strait, part of preparations for taking the city.

Ottoman forces began the siege in early April 1453, blockading the city by land and sea and repeatedly bombarding its defenses with cannon. The defenders, led by Emperor Constantine XI Palaeologus, resisted assaults and repaired damaged sections of the walls, but they lacked the numbers and outside support needed to end the encirclement. On 29 May, Mehmed launched a final assault; Ottoman troops entered the city through breaches in its defenses. Constantine XI was reported to have died during the fighting, though accounts differ about the exact circumstances of his death.

The capture ended the Byzantine Empire’s rule from Constantinople. Mehmed II made the city an Ottoman imperial capital, and it remained central to Ottoman government for centuries. After the conquest, Hagia Sophia—previously the principal church of the Byzantine capital—was converted into a mosque. The city’s later architecture and urban landscape combined structures from Byzantine and Ottoman periods, a layered history reflected in the monuments recognized by UNESCO’s Historic Areas of Istanbul listing.

The conquest brought a longstanding imperial capital under Ottoman rule and consolidated the sultanate’s position between southeastern Europe and Anatolia. It ended the Byzantine Empire as a political state, but not the city’s history: Constantinople remained an imperial capital under Ottoman rule, and its urban heritage includes structures from both Byzantine and Ottoman periods.