 After taking Apulia and Calabria, he occupied Messina with an army of 700 knights.In 1068, Robert Guiscard and his men defeated the Muslims at Misilmeri; but the most crucial battle was the siege of Palermo, which led to Sicily being completely in Norman control by 1091.Many historians have recently argued that the Norman conquest of Islamic Sicily (1060–91) was the start of the Crusades.