As in eastern Greece, the restoration of Byzantine rule seems to have proceeded from the islands, chiefly Cephallonia, which was certainly under firm Imperial control in , when Philippicus Bardanes was banished there. The gradual restoration of Imperial rule is evidenced further from the participation of local bishops in councils in Constantinople: whereas only the bishop of Dyrrhachium participated in the Ecumenical Councils of 680/1 and 692, a century later the bishops of Dyrrhachium, Nicopolis, Corfu, Cephallonia, and Zakynthos are attested in the Second Council of Nicaea in 787. In about the middle of the 8th century, the Theme of Cephallenia was established, but at least initially it was more oriented towards restoring Byzantine control over the Ionian and Adriatic seas, combating Saracen piracy, and securing communications with the remaining Byzantine possessions in Italy, rather than any systematic effort at subduing the Epirote mainland. Nevertheless, following the onset of the Muslim conquest of Sicily in 827, the Ionian became particularly exposed to Arab raids.