ROBERTO il GUISCARDO (the Cunning). - Son of Tancredi of Hauteville, he came to Italy in the fourth decade of the 11th century. He was a valiant warrior and an extremely able politician.
He first entered the service of the Lombard princes of Capua, then passed under the command of his half-brother Drogone, count of Apulia, who sent him to fight on behalf of another half-brother, Humphrey, who had succeeded Drogone (1051). He took a valiant part in the battle of Civitate (1053) against Leo I, and upon Humphrey’s death he imposed himself as count of Apulia, excluding the latter’s sons from the succession (Aug. 1057). In 1058, during a truce with Gisulf of Salerno, he married the latter’s sister Sichelgaita. In 1059 he concluded with Nicholas II the agreement of Melfi, which made him a vassal of the Holy See for the territories he already possessed and those he would conquer, with the title of Duke of Apulia, Calabria, and Sicily. The occupation of Calabria was completed by the last of the Hauteville brothers, Roger (v. RUGGERO I, count of Sicily), with the capture of Reggio in 1060. The following year operations began against the Muslims for the conquest of Sicily. R., the promoter of the enterprise, intervened only at certain moments, taking part in the liberation of Messina (1061), the conquest of Catania (1071), and of Palermo (1072), and invested his brother with the Calabrian and Sicilian territories occupied and to be occupied, with the title of Count of Calabria and Sicily, reserving for himself the high sovereignty and direct dominion over half of the city of Palermo, half of the city of Messina, and the Val Demone. Meanwhile, R. marked the end of Byzantine rule in Italy with the surrender of Bari (1071), and with those of Salerno (1077) and Benevento (1078) the end of the respective Lombard principalities.
In 1080 (June 29) R. renewed at Ceprano with Gregory VII the pact of Melfi and received from him the standard of St. Peter with the obligation to defend it against his enemies. In 1081, under the pretext of a Byzantine dynastic crisis involving one of his daughters, who had married the son of Michael VII Ducas, but in reality to forestall any possible attempts at recovery, he armed an expedition against the Eastern Empire which crossed Epirus and Macedonia, reaching as far as Thessalonica. Recalled to Italy by a revolt in 1082, while the expeditionary force remaining in the East under the command of his son Bohemond failed to maintain the positions gained, he hastened to the aid of Gregory VII, besieged by Henry IV. The Norman army caused further severe damage to the city, already hard-hit by the siege. In the autumn of 1084 he resumed the campaign against the Byzantines, but his death (July 17, 1085) at Cephalonia and the civil war among his sons prevented the continuation of the enterprise.
The Norman and native lords and the urban populations bore poorly the supremacy of R., which had been asserted in a brigand-like and ferocious manner, and frequent rebellions spread through the lands subject to him. Yet he made use of the feudal bond, firmly controlled by sovereign authority, to bind to himself both independent Normans and natives. From Leo IX to Gregory VII, the popes feared his expansive power toward the north, but recognized in him the only support against the Empire and the means to bring back under direct subjection to Rome the Churches that the Byzantine Empire had subjected to the patriarchate of Constantinople.