In the struggle between the emperors and the popes, Nepi was imperialist during the reigns of Pope Alexander II, Pope Nicholas II, Pope Gregory VII, and Pope Innocent II; on the other hand, in 1160, it fought against the commune of Rome, and in 1244, was besieged by Emperor Frederick II. A feudal possession, first of the prefects of Vico, and then of the Orsinis, of the Colonnas, and of C�sar Borgia, from 1537 to 1545, it was erected into a duchy in favour of Peter Louis Farnese; and when the latter was transferred to Parma, Nepi returned to immediate dependence on the Holy See. In 1798 the French set fire to the cathedral and to the episcopal palace, and archives were lost.
The Church of Nepi, which venerates, as its evangelizer, St. Ptolemaeus, who, it is claimed, was a disciple of the Apostles. In 419, Eulalius, competitor of Pope Boniface I, was made Bishop of Nepi; Bishop Paulus was sent as visitor to Naples by Gregory the Great; Bishop Stephanus, in 868, was one of the presidents and papal legates of the Council of Constantinople against Photius.
Sutri is placed on the Cassian Way. The cathedral is of the thirteenth century, modernized by frequent alterations. Santa Maria della Grotta is an interesting church. The history of Sutri in antiquity resembles that of Nepi, for Sutri also was taken by the Lombards in 569, but was retaken by the exarch Romanus; Luitprand likewise took the town in 726, but in the following year restored it to "St. Peter". As the city is on the Cassian Way not far from Rome, it was, as a rule, the last halting-place of the German emperors on their way to the city, and sometimes they received there the papal legate.
This town has an ancient Christian cemetery where the body of St. Romanus was found, who is the patron of the city; the cathedral possesses a statue of him by Bernini. Among the martyrs of Sutri is St. Felix (about 275). The first bishop of known date was Eusebius (465); other bishops were Martinus, or Marinus, who was sent as ambassador to Otho I in 963; Benedictus, who, in 975, became Pope Benedict VII; Bishop Bonitho (Bonizo), historian of the Gregorian epoch, who was driven from his diocese by the anti-papal faction and later was made Bishop of Piacenza.
The diocese was united to Nepi under Bishop Luke de Tartarts (1345); under Pomponius Cesi (1519), who became a cardinal, the cemetery of St. Savinilla was discovered; Michael Ghislieri (1556) became Pope Pius V; Joseph Chianti (1701) founded the seminary; Camillus Simeoni (1782) was exiled by the French and became a cardinal.