Norman infiltration in the Italian peninsula can be viewed as the story of a few hundred men who descended upon Italy to make a career for themselves as mercenaries, as soldiers of fortune. These people were predominantly Norman, as most of our sources agree, but perhaps as many as a third of them were immigrants from regions neighbouring Normandy, such as Maine, Anjou and Brittany. In this light, one should expect them to have attempted to introduce into Italy an administrative system based on their own experience at home, influenced no doubt by the forms of lord–vassal relations, and the customs of tenure, military service and inheritance established in Normandy and other parts of France in the previous decades.

The political and social backdrop of southern Italy was ideal for them, as the politically fragmented Lombard principalities, the Byzantine catepans, the great ecclesiastical institutions of the time and even the German emperors were more than willing to hire these fine cavalrymen into their service. A sharp distinction, however, should be drawn between the pre-Civitate period and that which followed the battle at the River Fortone in 1053. Civitate should be viewed as a pivotal moment in Italian medieval history for the simple reason that it established the Normans as a major player in the political arena of Italy. For the first four decades leading up to Civitate, the Normans served in Lombard rebel armies as elite cavalry units in a conspicuously auxiliary role. Their low numbers (just a few hundred) rendered them unable to influence Italian politics to any great measure.