ALEXIUS IV. (d. 1204), Byzantine Emperor, When Isaac II. was dethroned and blinded by his brother Alexius III., his son Alexius escaped, in 1201, to Germany, where he persuaded his brother-in-law, Philip of Suabia, and Boniface of Montferrat, the leader of the crusaders, to divert the fourth crusade to Constantinople. By 1203 Isaac was restored, with Alexius as joint emperor, but they were unable to fulfil the promises made to the crusaders that they would contribute men and money to the expedition to Jerusalem and would force the East to conform to the Western Church. In Jan. 1204 quarrels broke out between the crusaders and the Greeks, who revolted under the leadership of Murzuphlus. An officer, Canabus, was put on the throne, but was imprisoned by Murzuphlus, who had Alexius strangled, while Isaac died of shock. At this the crusaders, in self-defence against the Greeks, stormed and captured Constantinople a second time and elected Baldwin of Flanders as Latin Emperor. (See CRU SADES ; also DANDOLO.)