William I of Sicily (1131-7 May 1166) was King of Sicily from 26 February 1154 to 7 May 1166, succeeding Roger II of Sicily and preceding William II of Sicily.
Biography[]
William was born in 1131, the son of King Roger II of Sicily and Elvira of Castile. He did not expect to ever become King of Sicily, but the deaths of his brothers Roger III of Apulia, Tancred of Bari, and Alfonso of Capua led to William succeeding his father on his death in 1154. Lacking the support of Pope Adrian IV, William had to deal with Manuel I of Byzantium and Frederick Barbarossa, who encouraged the barons to rebel against him. By 1155, Bari, Trani, Giovinazzo, Andria, and Taranto were recaptured by the Byzantines, and Brindisi was besieged. On 28 May 1156, William destroyed the four ships of the Greek fleet and the Byzantine army, and he recovered Bari. On 18 June, Emperor Manuel recognized William as King of Sicily, but in 1157 he sent 164 ships and 10,000 Sicilian troops to sack Euboea and Almira in Greece before making peace once more in 1158. During his reign, he abandoned Sicily's lands in North Africa to the Saracens, losing Sfax in 1156. He sent a fleet under Ahmed es-Sikeli to sack the Balearic Islands in 1159, but the fleet failed to relieve Mahdia, Tunisia which fell on 11 January 1160 along with the "African empire" of Sicily. William quelled a revolt by his illegitimate half-brother Simon of Taranto in November, and he crushed the Sicilian revolt. He died in 1166, leaving behind four sons: Roger IV of Apulia, Robert III of Capua, William II of Sicily, and Henry of Capua.