Alexius V(Alexius Ducas Mourtzouphlos) (əlĕk`sēəs, do͞o`kəsmo͝ort`so͞oflŏs), 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 CrusadesCrusades
, series of wars undertaken by European Christians between the 11th and 14th cent. to recover the Holy Land from the Muslims. First Crusade
In the 7th cent., Jerusalem was taken by the caliph Umar.
..... Click the link for more information. ). He was deposed and executed, and Baldwin I was elected by the Crusaders as Latin emperor of Constantinople.