Turning his attention to the Balkans in 1081, Guiscard gained a great victory over the Byzantine emperor Alexius I Comnenus at Durazzo (Albania). In Greece, his campaigns at Macedonia and Thessalia were being carried on, meanwhile, by his son Bohamund. Robert was recalled from his victorious campaigns in 1084 to go to the aid of Pope Gregory VII, who was besieged in the castle of Sant'Angelo by Holy Roman Emperor Henry IV. Robert drove Henry from Rome, and reduced one-third of the city to ashes. Because of the unpopularity of Gregory VII in Rome, he took the pope to Monte Cassino. Robert then went to the support of Bohamund in the Greek campaign but died of fever at Kefalonia a few weeks later (July 1085). He was buried in the Hauteville family mausoleum of the Trinity Abbey (SS. Trinità) at Venosa. The town of Fiscardo on Kefalonia is named after him.