The Venetian fleet that ferried the forces of the Fourth Crusade to Constantinople in 1203 carried the blinded Isaac II and his son, Alexius. We know from western sources that Alexius offered the Venetians full payment of the sum specified in their contract with the leaders of the Fourth Crusade. Therefore, instead of ferrying the Latins directly to the Holy Land, the fleet sailed via Zadar to Constantinople in order to install Alexius IV on the imperial throne.

From Paul Stephenson’s Byzantium’s Balkan Frontier: A Political Study of the Northern Balkans, 900-1204, Cambridge: Cambridge University Press, 2000, p. 279.