 Although Sicily had been raided by the Muslims since the mid-7th century, these raids did not threaten Byzantine control over the island, which remained a largely peaceful backwater.The opportunity for the Aghlabid emirs of Ifriqiya came in 827, when the commander of the island's fleet, Euphemius, rose in revolt against the Byzantine Emperor Michael II.Defeated by loyalist forces and driven from the island, Euphemius sought the aid of the Aghlabids.