William II of Sicily William II ( 1155 – 11 November 1189 ) , called the Good , was king of Sicily from 1166 to 1189 . William ' s character is very indistinct . Lacking in military enterprise , secluded and pleasure - loving , he seldom emerged from his palace life at Palermo . Yet his reign is marked by an ambitious foreign policy and a vigorous diplomacy . Champion of the papacy and in secret league with the Lombard cities he was able to defy the common enemy , Frederick I Barbarossa . In the " Divine Comedy " , Dante places William II in Paradise . He is also referred to in Boccaccio ' s " Decameron " ( tale V . 7 ) . Kingship . Regency of his mother . William was only eleven years old at the death of his father William I , when he was placed under the regency of his mother , Margaret of Navarre . Until the king was declared adult in 1171 the government was controlled first by the chancellor Stephen du Perche ( 1166 – 1168 ) , cousin of Margaret , and then by Walter Ophamil , archbishop of Palermo , and Matthew of Ajello , the vice - chancellor . Marriage and alliances . In 1174 and 1175 William made treaties with Genoa and Venice and his marriage in February 1177 with Joan , daughter of Henry II of England and Eleanor of Aquitaine , marks his high position in European politics . This was not his first attempted marriage , an earlier effort by Bertrand II , archbishop of Trani , to negotiate the hand of a Byzantine princess yielded no fruit . In July 1177 , William sent a delegation of Archbishop Romuald of Salerno and Count Roger of Andria to sign the Treaty of Venice with the emperor . To secure the peace , he sanctioned the marriage of his aunt Constance , daughter of Roger II , with Frederick ' s son Henry , afterwards the emperor Henry VI , causing a general oath to be taken to her as his successor in case of his death without heirs . This step , fatal to the Norman kingdom , was possibly taken that William might devote himself to foreign conquests . Wars with Egypt and Greece . Unable to revive the African dominion , William directed his attack on Egypt , from which Saladin threatened the Latin kingdom of Jerusalem . In July 1174 , 30 , 000 men were landed before Alexandria , but Saladin ' s arrival forced the Sicilians to re - embark in disorder . A better prospect opened in the confusion in Byzantine affairs which followed the death of Manuel Comnenus ( 1180 ) , and William took up the old design and feud against the Byzantine empire . Dyrrhachium was captured ( 11 June 1185 ) . Afterwards while the army ( allegedly 80 , 000 men including 5 , 000 knights ) marched upon Thessalonica , the fleet ( 200 ships ) sailed towards the same target capturing on their way the Ionian islands of Corfu , Cephalonia , Ithaca and Zakynthos . In August Thessalonica fell to the joint attack of the Sicilian fleet and army and was subsequently sacked ( 7 , 000 Greeks died ) . The troops then marched upon the capital , but the army of the emperor Isaac Angelus defeated the invaders on the banks of the Strymon ( 7 November 1185 ) . Thessalonica was at once abandoned and in 1189 William made peace with Isaac , abandoning all the conquests . He was now planning to induce the crusading armies of the West to pass through his territories , and seemed about to play a leading part in the Third Crusade . His admiral Margarito , a naval genius equal to George of Antioch , with 60 vessels kept the eastern Mediterranean open for the Franks , and forced the all - victorious Saladin to retire from before Tripoli in the spring of 1188 . Death . In November 1189 William died at Palermo , leaving no children . Though Orderic Vitalis records a ( presumably short - lived ) son in 1181 : Bohemond , Duke of Apulia . William ' s title of " the Good " is due perhaps less to his character than to the cessation of internal troubles in his reign .