Isernia and Venafro, Diocese of.—Isernia is a city in the province of Campobasso in Molise (Southern Italy), situated on an eminence between Monte Matese and Monte Azzo, in a fertile region not far from Volturno. In the Middle Ages it was noted for the manufacture of parchment, which is carried on there even today. It was anciently called Aesernia, and was one of the principal cities of the Samnites. In 295 B.C. it was conquered by the Romans. In the Punic Wars, and, later, in the Social War, it was faithful to the Romans, though in 90 B.C. it was compelled to surrender, after a long resistance, to Vettius Cato, the general of the Samnites. As it was falling into decay, Caesar Augustus and Nero sent colonies there. Of ancient monuments there are a Roman bridge, the remains of an aqueduct, and especially the lower part of the high walls, formed of massive polygonal blocks, a pre-Roman work. After the Lombardic invasion it was the seat of a countship, founded by the Duke of Benevento. It was destroyed by the Saracens in the ninth century, and in 1199 was sacked by Marcolvaldo, the vicar of the deceased Henry VI. In 1805 it was visited by a severe earthquake, which ruined the ancient cathedral. A very distinguished native of Isernia was the jurisconsult, Andrea d'Isernia (Rampini), professor at the University of Naples (1230-1316); St. Peter Celestine also was of Isernia. According to tradition the Faith was preached at Isernia by St. Photinus, a disciple of St. Peter. More trust-worthy is the account of the martyrdom of Sts. Nicandrus and Marcianus, under Diocletian. The epoch of the saintly Bishop Benedict is doubtful, though the existence of the episcopal see in the fifth century is certain.
In 1032 the Diocese of Venafro (formerly the seat of Roman country residences), which had its own bishops from the fifth century, was united to Isernia, and in 1230 it was again separated. Pius VII united the two Churches in 1818. The united dioceses are suffragans of Capua, have 39 parishes, with 58,000 souls, 1 Capuchin convent, 2 religious houses of women, and 1 educational institution for boys.