ROBERT GUISCARD (c. 1015-1085), duke of Apulia and Calabria, sixth of the twelve sons of Tancred de Hauteville, was born at Hauteville near Coutances in Normandy about the year 1015. At an early age he followed into Apulia his three elder brothers William Bras-de-fer, Drogo, and Humphrey, who had established a footing there as military adventurers; and in 1053 he took a prominent part in the battle of Civitella, which resulted in the defeat and captivity of Pope Leo IX. On the death of Humphrey in 1057 Robert, who already had earned the sobriquet of “Guiscard” (“Sagacious” or “Cunning”), succeeded to the chief command of the Norman troops, and, already designated by them duke of Apulia and Calabria, was confirmed in that title in 1059 by Pope Nicholas IL, who at the same time named him gonfalonier of the church. For the next one-and-twenty years he was continually engaged, along with his youngest brother Roger, in warlike operations against the Greeks and Saracens in the south of the Italian peninsula and in Sicily, the principal events being the capture of Bari in 1070, that of Palermo in the following year, and that of Salerno in 1077. In 1081 he felt himself strong enough to carry his arms abroad against Alexius Comnenus, ostensibly on behalf of the deposed emperor Michael Ducas, the father-in-law of his daughter. The defeat of Alexius under the walls of Durazzo in October 1081 was followed by the capture of that place in February 1082,...