Crusaders Breach Constantinople Walls
By early 1204 the Fourth Crusade had deviated far from its original goal of recapturing Jerusalem. Venetian and French forces instead targeted the Byzantine capital after disputes over payments and succession. On April 12, Crusader troops scaled the sea walls along the Golden Horn using siege towers and ladders. The breach allowed them to pour into the city, overwhelming defenders under Emperor Alexius V. Constantinople fell the next day, ending centuries of Byzantine control over the eastern Mediterranean and establishing a short-lived Latin Empire.
Why it matters: The sack permanently weakened the Byzantine Empire, accelerating its long decline and shifting trade and power toward Western Europe and the rising Ottoman state. It also deepened the schism between Catholic and Orthodox Christianity that persists today.