During the Social War (91-87 BC), Corfinium served as the headquarters of the Italic socii who fought for the extension of Roman citizenship to all of Italy.

Corfinium was the capital of the Paeligni, situated in the valley of the Aternus, near the point where that river's course suddenly makes a sharp turn and runs from southeasterly to northeasterly on towards the Adriatic Sea.

It was probably its military position that led to this distinction; but the allies seem to have destined it to be the permanent capital of Italy, and the rival of Rome, as they changed its name to Italica, and adorned it with a new and spacious forum and senate house, and other public buildings of a style corresponding to its intended greatness.

Inscriptions indicate that it continued to be a flourishing municipal town under the Roman Empire, and its prosperity is proved by the fact that its inhabitants were able to construct two aqueducts for supplying it with water, both of which are in great part hewn in the solid rock, and one of them is carried through a tunnel nearly 5 km (3.1 mi) in length.

[6] A part of the territory of Corfinium had been portioned out to new settlers as early as the time of the Gracchi: it received a fresh body of colonists under Augustus, but never assumed the title of a colony, all inscriptions giving it that of a municipium only.