In 1347, Dušan conquered Epirus, Aetolia and Acarnania, appointing his half-brother, despot Simeon Uroš as governor of those provinces. In 1348, Dušan also conquered Thessaly, appointing Preljub as governor. In eastern regions of Macedonia, he appointed Vojihna as governor of Drama. Once Dušan conquered Byzantine possessions in western regions, he sought to obtain Constantinople. To acquire the city, he needed a fleet. Knowing that fleets of southern Serbian Dalmatian towns were not strong enough to overcome Constantinople, he opened negotiations with Venice, with which he maintained fairly good relations. Venice feared a reduction of privileges in the Empire if Serbs became the masters of Constantinople over the weakened Byzantines. But if the Venetians had allied with Serbia, Dušan would have examined existing privileges. Once he became master of all Byzantine lands (especially Thessalonika and Constantinople) the Venetians would have gained privileges. But Venice chose to avoid a military alliance. While Dušan sought Venetian aid against Byzantium, the Venetians sought Serbian support in the struggle against the Hungarians over Dalmatia. When sensing that Serbian aid would result in a Venetian obligation to Serbia, Venice politely turned down Dušan's offers of help.
