The main historical interest of this page is the period that began the invasion of the Normans on Saracen held Sicily. Pope Leo, to rid Apuglia from the hold of the Normans offered Calabria and Sicily to them in exchange for their exit from Apuglia. Roger and Robert D'Altavilla accepted the offer. The only problem was Sicily was under the control of the Saracens. The documentary, "Barbarossa and the Towers of Italy" tells this story in beautiful HD video.

The following is from Wikipedia.

Between 1038 and 1040, another band of Normans were sent along with a Lombard contingent by Guaimar IV of Salerno to fight in Sicily for the Byzantines against the Saracens. The first members of the Hauteville family won renown in Sicily fighting under George Maniaches. William of Hauteville won his nickname "Iron Arm" at the siege of Syracuse.

After the assassination of the Catapan Nicephorus Doukeianos at Ascoli in 1040, the Normans planned to elect a leader from amongst their own, but were instead bribed by Atenulf, Prince of Benevento, to elect him their leader. On 16 March 1041, near Venosa, on the Olivento, the Norman army tried to negotiate with the new catapan, Michael Doukeianos, but failed and battle was joined at Montemaggiore, near Cannae. Though the catapan had called up a large Varangian force from Bari, the battle was a rout and many of Michael's soldiers drowned in the Ofanto on retreat.

On 3 September 1041, the Normans, nominally under the Lombard leadership of Arduin and Atenulf, defeated the new Byzantine catepan, Exaugustus Boioannes, and took him captive to Benevento, significant of the remaining Lombard influence over the conquests. Also about that time, Guaimar IV of Salerno began to draw the Normans under his banner with various promises. In February 1042, probably feeling abandoned, and perhaps bribed by the Greeks, Atenulf negotiated the ransom of Exaugustus and then fled with the ransom money to Greek territory. He was replaced by Argyrus, who won some early victories but then too was bribed to defect to the Greeks.

In September 1042, the Normans finally elected a leader from among their own. The revolt, originally Lombard, had become Norman in character and leadership. William Iron Arm was elected with the title of "count." He and the other leaders petitioned Guaimar for recognition of their conquests. They received the lands around Melfi as a fief and proclaimed Guaimar "Duke of Apulia and Calabria." At Melfi in 1043, Guaimar divided the region (except for Melfi itself, which was to be ruled on a republican model) into twelve baronies for the benefit of the Norman leaders: William himself received Ascoli, Asclettin received Acerenza, Tristan received Montepeloso, Hugh Tubœuf received Monopoli, Peter received Trani, Drogo of Hauteville received Venosa, and Ranulf Drengot, now independent, received Monte Gargano. William in turn was married to Guida, daughter of Guy, Duke of Sorrento, and niece of Guaimar. The alliance between the Normans and Guaimar was strong.

During his reign, William and Guaimar began the conquest of Calabria in 1044 and built the great castle of Stridula, probably near Squillace. William was less successful in Apulia, where, in 1045, he was defeated near Taranto by Argyrus, though his brother, Drogo, conquered Bovino. With William's death, however, the period of Norman mercenary service would come completely to and end and witness the rise of two great Norman principalities, both owing nominal allegiance to the Holy Roman Empire: the County of Aversa, later the Principality of Capua, and the County of Apulia, later the Duchy of Apulia.