The Siege of Constantinople occurred in 1453 when the Ottoman Empire, led by Sultan Mehmed II, attacked the city of Constantinople, the capital of the Byzantine Empire. The siege lasted for about two months, from April 6 to May 29, and involved large cannons and military tactics that overwhelmed the city's defenses. Despite fierce resistance from the Byzantine defenders, including Emperor Constantine XI, the Ottomans breached the walls and captured the city. This event marked the end of the Byzantine Empire and significantly expanded the Ottoman Empire, establishing Istanbul as a major cultural and political center.