Medieval Corsica Count of Corsica at Biguglia, even seizing Bastia. Lomellino was unable to make headway against him and, by 1410, all Corsica, with the exception of Bonifacio and Calvi, was lost to Genoa, now once more independent of France. A feud between Vincentello and the Bishop of Mariana, however, led to the loss of his authority in the Terra di Comune and he was compelled to go to Spain in search of assistance. In his absence the Genoese reconquered the island. At this stage, the Western Schism was underway in Roman Catholic Europe. Corsica itself became divided as the suffragan sees
Corsica was divided in "pagi", which in the Middle Ages became the "pievi", the basic administrative units of the island until 1768. During the diffusion of Christianity, which arrived quite early from Rome and the Tuscan harbors, Corsica was home to many martyrs and saints: among them, the most important are Saint Devota and Saint Julia, both patrons of the island. Corsica was integrated into Roman Italy by Emperor Diocletian (r. 284-305). In the 5th century, the western half of the Roman Empire collapsed, and the island was invaded by the Vandals and the Ostrogoths. Briefly recovered by the Byzantines, it