On 25 January 1204, the death of co-Emperor Isaac II set off rioting in Constantinople in which the people deposed Alexios IV, who turned to the Crusaders for help but was imprisoned by the imperial chamberlain, Alexios Doukas, who declared himself Emperor Alexios V on 5 February. Emperor Alexios V then attempted to negotiate with the Crusaders for a withdrawal from Byzantine territory, but they refused to abandon their old treaty with Alexios IV. When Alexios V ordered Alexios IV's execution on 8 February, the Crusaders declared war on Alexios V. In March 1204, the Crusader and Venetian leadership decided on the outright conquest of Constantinople, and drew up a formal agreement to divide the Byzantine Empire between them.