 Despite the relative peace of the early years of Selvo 's reign , the forces that would eventually lead to his deposition had already swung into action . In southern Italy , the Duke of Apulia and Calabria , Robert Guiscard , had spent the majority of his reign consolidating Norman power along the heel and toe of lo Stivale by expelling the Byzantine armies . Guiscard was pushing north toward the Papal States ( to which the Duchy of Apulia and Calabria was allied ) , and was threatening Byzantine control of cities along the Ionian and Adriatic seas . In May 1081 , Guiscard led his army and navy across the sea to lay siege to the port city of Durazzo , as it was one end of the famous Via Egnatia , a direct route to the Byzantine capital of Constantinople . Alexios I Komnenos , the newly crowned Byzantine Emperor , dispatched an urgent message to Selvo asking for the mobilization of the Venetian fleet in defense of Durazzo in return for great rewards . The Doge wasted no time in setting sail for the besieged city in charge of his fleet of 14 warships and 45 other vessels . Selvo was motivated not only by his familial ties and the promise of reward , but also the realization that Norman control over the Strait of Otranto would be just as great of a threat to Venetian power in the region as it would be to their ally in the east . 
