Byzantine emperor (1203-1204).
The son of Emperor Isaac II Angelos, Alexios was incarcerated when his father was overthown and blinded by his uncle, Isaac’s brother, Alexios III Angelos (8 April 1195). In late 1201 the young Alexios escaped to Italy and made his way to the court of Philip of Swabia, king of Germany, the husband of his sister Irene Angelina. Philip supported Alex- ios’s claims to the Byzantine throne and put him in contact with the republic of Venice, which had supplied the fleet that was intended to transport the Fourth Crusade to Egypt. By January 1203 Alexios had joined the crusaders at Zara, promising them large sums of money and the submission of the Greek Orthodox Church to the papacy in exchange for their assistance in restoring him to the throne of Byzantium, and a pact between Alexios and the crusaders was agreed on at Corfu in May 1203. On 17/18 July 1203, Alexios III was ousted from the Byzantine capital, and Isaac II was restored, with Alexios IV as co-emperor and effective ruler (August 1203). The pro-Latin attitude of the young Alexios estranged him from his own subjects, yet he soon proved incapable of fulfilling his promises to the crusaders. Unable to settle his enormous debts, he was compelled to increase the already cumbersome taxation set by his predecessor, and growing discontent gave way to open rebellion under the nobleman Alexios (V) Doukas Mourtzouphlos, who seized power (28/29 January 1204) and had Alexios IV strangled in prison ten days later (8 February 1204).