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Born circa 1015; died July 17, 1085, on the island of Cephalonia. One of the leaders of the Norman invasions of Italy.
Robert fought in wars against the Byzantines for possession of southern Italy and in 1053 defeated the forces of Pope Leo IX at Civitate. In 1057 he became count of Apulia. Pope Nicholas II legalized Robert’s conquests (future as well as actual), confirming him as duke of Apulia, Calabria, and Sicily in 1059, and Robert took an oath of fealty to the pope. By 1072 he ruled southern Italy and Sicily (conquered from the Arabs), laying the foundations for the Kingdom of Sicily.
In an attempt to halt Robert’s conquests, Pope Gregory VII excommunicated him in 1074; in 1080 he lifted the excommunication and gave Robert all the lands he had conquered, including Amalfi and Salerno, as fiefdoms, in the hope of securing Robert’s aid in the struggle against Emperor Henry IV. Still at war with Byzantium, Robert invaded the Balkan Peninsula, defeating the forces of Alexius I Comnenus at Dyrrachium in 1081. In 1084 he went to the aid of Pope Gregory, who was besieged in Rome by Henry. Robert drove Henry out of Rome, sacking the city in the process. Robert died at the height of the renewed war with Byzantium.