What was the “Fourth Crusade” (1202–1204) notorious for capturing?

The story behind the answer

Launched to retake the Holy Land, the Fourth Crusade was derailed by debt to Venice and a Byzantine succession crisis. After helping Venice seize Zara, crusader leaders accepted a deal to back a claimant to the Byzantine throne. When promises collapsed, they besieged and brutally sacked the imperial capital in 1204, installing a Latin Empire instead of marching to Jerusalem.

The conquest devastated a major Christian city, poisoned relations between the Latin West and the Orthodox East, and crippled Byzantine power, leaving it vulnerable to later Ottoman expansion. Venice gained immense commercial advantages and treasured relics, while the crusade’s reputation was permanently stained as a cautionary tale of diverted aims and political manipulation.