After a failed siege months earlier, Crusader knights and Venetian sailors stormed Constantinople's sea walls, looting churches, palaces, and the Hagia Sophia itself over three days. The sack diverted a crusade meant for Jerusalem into the conquest of a fellow Christian empire, fracturing Byzantium into rival states and accelerating a decline that ended in the city's fall to the Ottomans in 1453.
The Fourth Crusade had already gone badly awry before troops ever reached Constantinople's walls, diverted first to Zara and then embroiled in Byzantine dynastic politics after agreeing to help a deposed emperor's son reclaim his throne in exchange for funding the crusade to Jerusalem. When that money failed to materialize, the crusaders, deeply in debt to Venice, turned their siege engines on the city that was supposed to be their ally.
Venetian doge Enrico Dandolo, blind and elderly, reportedly stood at the prow of his galley urging the assault forward as it ran aground beneath the sea walls. On April 12, the attackers finally broke through, and the ensuing three-day sack was ferocious: soldiers looted monasteries, melted down bronze statues for coin, and carried off relics and treasures still displayed today in Venice, including the four bronze horses now atop St. Mark's Basilica.
Byzantine chronicler Niketas Choniates described prostitutes installed in the patriarch's seat at Hagia Sophia as a symbol of the desecration. The empire never fully recovered, splintering into competing Greek and Latin states until a diminished Byzantium was finally extinguished by the Ottomans two and a half centuries later.
Key people: Enrico Dandolo, Boniface of Montferrat