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. The 9th century saw great progress in the restoration of Imperial control in the mainland, as evidenced by the participation of the bishops of Ioannina, Naupaktos, Hadrianopolis, and Vagenetia (evidently by now organized as a Sklavinia under imperial rule) in the Ecumenical Councils of 869/70 and 879/80. The Byzantine recovery resulted in an influx of Greeks from southern Italy and Asia Minor into the Greek interior, while remaining Slavs were Christianized and Hellenized. The eventual success of the Hellenization campaign also suggests a continuity of the original Greek population, and that the Slavs had settled among many Greeks, in contrast to areas further north, in what is now Bulgaria and the former Yugoslavia, as those areas could not be Hellenized when they were recovered by the Byzantines in the early 11th century. Following the great naval victory of admiral Nasar in 880, and the beginning of the Byzantine offensive against the Arabs in southern Italy in the 880s, the security situation improved and the Theme of Nicopolis was established, most likely after 886. As the ancient capital of Epirus had been laid waste by the Slavs, the capital of the new theme became Naupaktos further south. The extent of the new province is unclear, but probably matched the extent of the Metropolis of Naupaktos, established at about the same time, encompassing the sees of Vonditsa, Aetos, Acheloos, Rogoi, Ioannina, Hadrianopolis, Photike, and Buthrotum. Vagenetia notably no longer appears as a bishopric. As the authors of the Tabula Imperii Byzantini comment, it appears that "the Byzantine administration had brought the strongly Slavic-settled