Alexius V (Alexius Ducas Mourtzouphlos)əlĕkˈsēəs, dōˈkəsmŏrtˈsōflŏs, d. 1204, Byzantine emperor (1204), son-in-law of Alexius III. The head of the Byzantine national party, he overthrew emperors Isaac II and Alexius IV (who had been installed by the Crusaders), thus precipitating the conquest and sack of Constantinople (1204) by the army of the Fourth Crusade (see Crusades). He was deposed and executed, and Baldwin I was elected by the Crusaders as Latin emperor of Constantinople.
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