This action angered the people of Rome, who viewed Tibur as a rival and wanted the city destroyed. In a change of policy towards the papacy, Otto III bestowed the governance of the city upon Pope Sylvester II as part of the Papal States but under the overlordship of the Holy Roman Empire. Previously, Otto III had revoked the Pope's rights as secular ruler by denying the Donation of Constantine and by amending the Diploma Ottonianum. In the weeks after Otto's actions at Tibur, the Roman people rebelled against their Emperor, led by Count Gregory I of Tusculum. The rebellious citizens besieged the Emperor in his palace on the Palatine Hill and drove him from the city. Accompanied by Bishop Bernward of Hildesheim and the German chronicler Thangmar, he returned to the city to conduct peace negotiations with the rebellious Romans. Though both sides agreed to a peaceful settlement, with the Romans respecting Otto's rule over the city, feelings of mistrust remained. The Emperor's advisors urged him to wait outside the city until military reinforcements could arrive to ensure his safety. Emperor Otto, accompanied by Pope Sylvester II, traveled to Ravenna to do penance in the monastery of Sant'Apollinare in Classe and to summon his army. While in Ravenna, he received ambassadors from Duke Bolesław I of Poland and approved the plans of King Stephen of Hungary to establish the Archdiocese of Esztergom in order to convert Hungary to Christianity. The Emperor also strengthened relations with the Venetian Doge, Pietro II Orseolo. Since 996, Otto had been godfather to Pietro II's son, Otto Orseolo, and in 1001 he arranged for Pietro II's daughter to be baptized. Death After summoning his army in late 1001, Otto headed south to Rome to ensure his rule over the city. During the travel south, however, he suffered a sudden and severe fever. He died in a castle near Civita Castellana on 24 January 1002. He was 21 years old and had reigned as an independent ruler for just under six years, having nominally reigned for nearly nineteen. The Byzantine princess Zoe, second daughter of the Emperor Constantine VIII, had just disembarked in Apulia on her way to marry him. Otto III's death has been attributed to various causes. Medieval sources speak of malaria, which he had caught in the unhealthy marshes that surrounded Ravenna. Following his death, the Roman people suggested that Stefania, the