From what I have learned the Fourth Crusade was a failure. Much to the Pope’s disapproval the measly crusaders were dumb enough to get sidetracked on their journey to conquer the holy cities. The true heir to the throne in Constantinople, Alexius, was not emperor and wanted the power immensely so he enlisted the crusaders’ help by promising them much needed money in return for the throne. After much trouble the crusaders were finally able to get Alexius his rightful position and were paid half of what they had been promised. Alexius then raided the tombs of past emperors in order to acquire the rest of the money needed to pay the crusaders. His actions were not welcomed by the people, he was murdered and replace by his second in command. How were the crusaders to get the rest of their money now? The new emperor had made no promise of money to them so they decided to sack Constantinople and take rein over it. They held power over the city for half a century.
Meanwhile the Pope had excommunicated the crusade wanting no part in it. This embarrassing outcome the fourth crusade made the division between the west and the east even worse.