[3] That the existence of the episcopal see in the fifth century is certain is likewise a doubtful proposition;[4] each of the purported bishops has been assigned to other dioceses.

[10] In 1032 the Diocese of Venafro (The town was formerly the site of Roman country residences) was united to Isernia,[11] and in 1230 it was again separated.

On 12 November 1192, the city of Venafro was sacked and burned by the German troops of the Emperor Henry VI, led by Duke Bertold.

Numerous citations of the parties to appear before Cardinal Gerardo of S. Adriano, the judge whom Pope Celestine III had appointed, were ignored or put off to a later time.

[17] The right of the king to nominate the candidate for a vacant bishopric was recognized, as in the Concordat of 1741, subject to papal confirmation (preconisation).

[18] On 27 June 1818, Pius VII issued the bull De Ulteriore, in which he reestablished the metropolitan archbishopric of Capua, and assigned as suffragan (subordinate) dioceses: Isernia, Calvi, Suessa, and Caserta.

His decree "Ad Apicem Spiritualis" of 21 August 1976 created a new episcopal conference in the region called "Molise", to be called "Boianensis-Campobassensis", with the archdiocese of Boiano-Campobasso, formerly directly subject to the Holy See, to be the Metropolitan; its suffragans were to be the dioceses of Trivento, Isernia e Venafra, and Thermulae e Larino.

Based on the revisions, a set of Normae was issued on 15 November 1984, which was accompanied in the next year, on 3 June 1985, by enabling legislation.

According to the agreement, the practice of having one bishop govern two separate dioceses at the same time, aeque personaliter, was abolished.