He was old (at least in his late seventies when he became Doge), and blind, but displayed tremendous physical and mental strength. He persuaded the Crusaders to help him capture Zara[?] in return for naval transportation to the Kingdom of Jerusalem, as well as forgivement of debts they had run up while waiting for passage from Venice.
Following the capture and sack of Zara (November 15, 1202), Alexius arrived in that city, and with Dandolo's help, convinced the crusaders to restore him to the throne of the Byzantine Empire. This led to the eventual sack of Constantinople on April 12, 1204, at which event Dandolo played a direct role.
He was active enough to take part in an expedition against the Bulgars, but died in 1205. He was buried in Constantinople.
wikipedia.org dumped 2003-03-17 with terodump