Editing Robert Guiscard (section)

===Accession to the throne and treaty of Melfi===
[[File:Roberto il Guiscardo Costantino.jpg|thumbnail|left|Robert Guiscard and Sikelgaita welcoming [[Constantine the African]] to court]]                                                                                                               When Humphrey died in 1057, Guiscard succeeded him as [[County of Apulia and Calabria|Count of Apulia and Calabria]], skipping over his elder half-brother [[Geoffrey of Hauteville|Geoffrey]] in the line of succession. Soon after, probably in 1058, Guiscard's marriage to Alberada was annulled due to [[consanguinity]]. It was the first time that a marriage was annulled for this cause. After that, Robert married [[Sikelgaita]], sister of [[Gisulf II of Salerno]], securing a new alliance between Lombards and Normans. In return for his sister's hand in marriage, Gisulf demanded that Guiscard destroyed two castles which belonged to his brother [[William of the Principate|William]], because they stood on Gisulf's territory.

The Papacy, in a conflict with the [[Holy Roman Emperor]] due to the [[Investiture Controversy]], now opted to secure the Normans as allies. Therefore, in the [[Treaty of Melfi]] of 1059, Guiscard swore fealty to [[Pope Nicholas II]]. In return, Nicholas invested Guiscard of the titles of [[Duke of Apulia and Calabria]] and [[County of Sicily|Lord of Sicily]] (''by the Grace of God and St Peter duke of Apulia and Calabria and, if either aid me, future lord of Sicily''), legitimizing his intervention against the [[Muslim Sicily|Sicilian emirates]], of [[Islam|Muslim]] faith.<ref name=":0" /><ref>''The Normans in Europe'', Ed. & Trans. Elisabeth van Houts (Manchester & New York: Manchester University Press, 2000), pp. 236–237</ref>