Thanks VR.
http://en.wikipedia.org/wiki/Norman_conquest_of_southern_Italy
http://en.wikipedia.org/wiki/ByzantineNorman_wars
It looks like I was not quite accurate—the Normans had invaded Sicily in 1061 and 1064, but the only lasting possession from those attempts was the castle of San Marco d’Alunzio, built in 1061.