In May 1084, Guiscard marched north with 36,000 men, entered Rome, and forced Henry to retreat. A rebellion, or seditious tumult ("émeute"), of the citizens led to a three-day sack of the city, after which Guiscard escorted the pope to Rome. Guiscard's son Bohemund, for a time master of Thessaly, had now lost the Byzantine conquests. Guiscard returned with 150 ships to restore them, and he occupied Corfu and Kefalonia with the help of Ragusa and the Dalmatian cities (which were under the rule of Demetrius Zvonimir of Croatia). On 17 July 1085, Guiscard died of fever in Kefalonia, at Atheras, north of Lixouri, along with 500 Norman knights. He was buried in the Hauteville family mausoleum of the Abbey of the Santissima Trinità at Venosa. The town of Fiscardo on Kefalonia is named after him.