Robert Guiscard, entered at the dawn of the Norman conquest of Italy, defeated his enemies and pushed aside his competing family members to take the whole of southern Italy, much of Sicily, and parts of the Balkan Peninsula.
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- Robert C. L. Holmes, American International Journal of Social Science, “Men of the North Wind the Norman Knight in the 11th Century Mediterranean.” 2015
- Hubert Houben, Roger II of Sicily: A Ruler Between East and West. 2002
- Edmund Curtis, Roger of Sicily and the Normans in Lower Italy, 1016-1154. 1912
- Karen C. Britt, Mediterranean Studies, “Roger II of Sicily: Rex, Basileus, and Khalif? Identity, Politics, and Propaganda in the Cappella Palatina” 2007
- Helene Wieruszowski, Speculum, “ Roger II of Sicily, Rex-Tyrannus, In Twelfth-Century Political Thought” 1963