The fourth crusade mostly killed Christians. Enrico Dandolo was an impressive charlatan that proved that the catholic church was just a vehicle of approving land grabs and looting.

Wtf is that shield and that armor? Someone played one too many fantasy games. Not that there is anything wrong with fantasy games but please don't conflate them with history...

I was always convinced that crusades "failed" about as much as American wars - the developments in some third country are irrelevant (and also subject to easy propaganda, since only one side can fud people), where the real money & power comes from is from campaigning, money collection, arms industry, etc. In that was a vast success. People that actually went crusading were just necessary with a secondary (low) possibility of extra payout.

Which Crusades though? The Eastern European and Spanish Crusaders were wildly successful with the crusaders achieving essentially every objective they had. The balkan crusades also had mixed success but were ostensibly a Crusader strategic victory. The genocides and mass conversion were successful.

The Holy Land crusades? Absolute disaster. Failed essentially every objective and lost massive swathes of men for literally nothing in return. A greed motivated land and capital grab.