The Normans in southern Italy and Sicily in 11th-12th century

The diploma thesis entitled "The Normans in the Southern Italy and Sicily in the 11th and 12th Century" includes the history of the region from the arrival of the first Norman warriors to the accession of the Staufen dynasty. It describes the fortunes of Norman mercenaries who were providing their military services to the antagonized parties competing in southern Italy. Progressively, the Normans built important military and political power in the territory. Robert Guiscard conquered southern Italy and threatened the Byzantine Empire in the Balkan Peninsula while his brother Roger I defeated Arabians and seized Sicily. Roger II, son of Roger I, overruled the other Norman domains but he had to repress an extensive revolt in his land. During the rule of his successors, the Kingdom was struck by inner conflicts as well, but the successors managed to overcome these difficulties. On William II's death, a war of succession broke out between Emperor Henry VI and Tancred of Lecce. Finally, the Tancred's death made a decision of war. After that Henry VI conquered the Sicilian Kingdom