On Ascension Day in 1000 a powerful fleet sailed from Venice to resolve the problem of the Narentine pirates. The fleet visited all the main Istrian and Dalmatian cities, whose citizens, exhausted by the wars between the Croatian king Svetislav and his brother Cresimir, swore an oath of fidelity to Venice. the Main Narentine harbours (Lagosta, Lissa and Curzola) tried to resist, but they were conquered and destroyed (see: battle of Lastovo). The Narentine pirates were suppressed permanently and disappeared. Dalmatia formally remained under Byzantine rule, but Orseolo became "Dux Dalmatie" (Duke of Dalmatia"), establishing the prominence of Venice over the Adriatic Sea. The "Marriage of the Sea" ceremony was established in this period. Orseolo died in 1008.