Which crusade do you think was the least successful and why?

The Fourth Crusade (1202-1204) is often considered the least successful due to its diversion from the original goal of reclaiming Jerusalem. Instead, the crusaders ended up sacking Constantinople, a Christian city, which weakened the Byzantine Empire and deepened the schism between Eastern and Western Christianity. This misdirection and the ensuing chaos not only failed to achieve its intended objectives but also led to long-term political and cultural ramifications in the region.