In 1649, in consequence of a conspiracy, Cristoforo Girarda, a Barnabite of Novara and Bishop of Castro, was assassinated in the Second War of Castro. In punishment of this crime, Pope Innocent X ordered Castro to be destroyed, and raised Acquapendente to the dignity of an episcopal city (Bull, 13 September 1649), directly under the Holy See. Its bishops, however, retained the appellation "post Castrenses." The first incumbent of the new See was the Hieronymite Pompeo Mignucci of Offida, who had been Archbishop of Ragusa. He took possession on 10 January 1650.
Bishop Nicolò Leti (1655–1674) held a diocesan synod in Acquapendente on 9–10 May 1660, and published the Constitutions of the synod.[3] Bishop Florido Pierleoni, C.O. (1802–1829) held a diocesan synod in 1818.[4]
By the middle of 1986, papal policy in the selection of bishops had concentrated in the person of Bishop Luigi Boccadoro: the Diocese of Viterbo e Tuscania, the diocese of Acquapendente (since 1951), the diocese of Montefiascone (since 1951), and the Administratorship of the diocese of Bagnoregio (since 1971); he was also the Abbot Commendatory of Monte Cimino. On September 30, 1986, Pope John Paul II moved to consolidate these several small dioceses by suppressing them and uniting their territories[5] into the diocese of Viterbo e Tuscania, whose name was changed to the Diocese of Viterbo.[6] The diocese of Acquapendente ceased to exist.
The title of Acquapendente, though not the diocese structure, was revived in 1991, to serve as a titular see. It is currently the episcopal title of an auxiliary bishop.
"in unam dioecesim iuridice redigeremus, satis enim eas coeptis, institutis, moribus, mente coaluisse....perpetuo unimus, unione, ut dicunt, exstinctiva; quae proinde adquiret atque comprehendet in suo territorio uniuscuiusque harum Ecclesiarum territorium"
Born in Offida (diocese of Ascoli Piceno), Mignucci held the degree of Doctor in utroque iure (Rome, 1617). In his Order he was commendatore di s. Giovanni di Pola e di s. Nicola di Gradisca. He served as Archbishop of Ragusa (1647–1650). He was appointed Bishop of Acquapendente by Pope Innocent X in the consistory of 10 January 1650. He died in October 1654. Cappelletti, Le chiese d'Italia V, pp. 573-574. Gauchat, Hierarchia catholica IV, pp. 88 with note 2; 291 with note 7.
On 12 April 1847 Salvini was appointed Archbishop of Camerino. The diocese of Acquapendente was offered to Msgr. Brioli, the Vicar-General of Rimini, but he declined the appointment. Cappelletti, p. 578. Ritzler-Sefrin, VII, p. 83; VIII, p. 176.
Foccaccetti had been Apostolic Administrator of the diocese of Acquapendente from 1867 to 1873, and was titular Bishop of Lystra (Turkey). He was appointed Bishop of Montefiascone on 25 July 1873, and transferred to the diocese of Acquapendente on 15 July 1878. He resigned on 14 May 1887, and was appointed TitularArchbishop of Hierapolis in Phrygia. He died on 26 September 1889. Ritzler-Sefrin, VIII, pp. 113, 305, 356, 393.
On his retirement on 15 December 1919, Veneri was appointed titular Bishop of Darnis (Libya). He died on 15 November 1937. Ritzler-Sefrin, VIII, p. 113.