Pope Innocent III, a primary organizer of the Venetian-backed Fourth Crusade—composed largely of Frenchmen, Venetians, and other Italians, collectively called Franks or Latins—has been unable to prevent its diversion, by the Venetians, to capture Constantinople.

Constantinople’s new coemperors, Isaac II Angelos and his son Alexios IV are unable to pay their debts to the West or to unite the two churches.

They have inspired little confidence among the people of Constantinople in their efforts to defend the city from the Latins and Venetians, who are restless and riot when the money and aid promised by Alexios IV is not forthcoming.

The courtier Alexios Doukas Mourtzouphlos, related to the imperial Doukas family, emerges as a leader of the anti-Latin movement and personally leads some skirmishes against the crusaders.

Heavy taxation, as well as wanton behavior on the part of the crusaders in Constantinople, causes a national revolt at the end of January 1204, when the populace of Constantinople rebels and tries to proclaim a rival emperor in Hagia Sophia.

The emperors barricade themselves in the palace and entrust Doukas with a mission to seek help from the crusaders.

Instead, Doukas uses his access to the palace to arrest the emperors, imprisoning both Alexios IV and his father on the night of January 27-28, 1204.