In his youth a sailor, he commanded a flotilla escorting the emperor Frederick Barbarossa in 1177, took also part in the Fourth Crusade and sacking of Constantinople. After his election, Ziani is said to consider the transfer of the capital of the Republic to Constantinople, but eventually the Council decided against it. Instead, he organized the Venetian acquisitions in the territory of the Latin Empire: Crete, Corfu, other islands and the substantial part of Constantinople itself, demanding an oath from the Venetian colony in the city. Ziani established also commercial ties with the post-Byzantine states, signing in 1210 a treaty with the despotate of Epirus under Michael I Komnenos Doukas.
According to the Cronaca Altinate, he strove to maintain peace with Padua after an incident at a festival in Treviso so that Venice could concentrate on its new Greek territories. He was forced to fend off a Paduan invasion in the War of the Castle of Love (1215).[1]
Ziani abdicated in February 1229. He was succeeded by his brother-in-law, Jacopo Tiepolo, but Ziani refused to meet him and died a year later. He is buried in the church of San Giorgio Maggiore.
