It was Robert who began the conquest of Sicily which was to yield a kingdom seventy years later, as he renewed the war against Byzantium with vigour. Along with the valiant warriorship displayed by his youngest brother, Roger Bosso, the two began to amass notoriety around the Mediterranean. According to William of Apulia's "The Deeds of Robert Guiscard", although his Norse roots would seem to suggest otherwise, until the invasion of Sicily, Guiscard had not participated in naval warfare. It was during this conquest that Guiscard and his amphibious command pioneered the ability to transport over 200 troops in a mere 13 vessels, an advantage that would have an influence in the Norman invasion of England. In 1059 he was created duke by the pope and invested with as yet unconquered Sicily, which he gave, in 1071, to his brother Roger with the title of count. The Guiscard's heirs, Bohemond and Roger Borsa, fought over the inheritance and Roger of Sicily began to outshine the Apulian branch of the family. Roger united the Greek, Lombard, Norman, and Saracen elements of Sicily under one rule and refused to allow religious differences to spoil his conquests.