Although partially ruined by the Visigoth raid in 396 A.D., Nafpaktos developed into an important port between Rome and Constantinople in late Antiquity and the early Byzantine period; it served as a naval base for the Byzantine fleet and it was adorned with important buildings under Justinian. The historian Procopius refers to the forifications of the city in his “Buildings” with particularly praising words. It seems, however, that its buildings suffered severe damages during the earthquake of 551-2 A.D. Initially it was ecclesiastically subordinate to the Bishoprics of Corinth and Athens. After the slavic raids (6th-10th centuries), however, its bishopric was upgraded, in order to proselytize the Slavs who had settled in the region as well as in the rest of Western mainland Greece. In the second half of the 8th century the Bishopric of Naupaktos falls within the realms of the vicariatum of Illyricum under the archbishop of Thessaloniki. Constantine Porphyrogennitus describes it as see of the “Thema Hellados”, where Ioannis Skylitzes in the 12th century refers to it as see of the Thema of Nicopolis. From 1025 onwards it is headquarters of a general, whereas in 1040 Nafpaktos was the only city of the Thema which withstood the Bulgarian raids of Petar Deljan.