[1][2] According to a local tradition, the first bishop of Terracina was St. Epaphroditus, who is claimed to have been one of Jesus' original seventy-two disciples, mentioned by Paul of Tarsus in one of his epistles.

[3] The most ancient Christian record of the city is that of the martyrdom of St. Julianus, priest, and St. Cæsareus, deacon, who were cast into the sea under the emperor Trajan.

The catalogue of Hieronymianus notes under 10 February: "iuxta Terracina in Campania natale Silvani episcopi et confessoris.

[8] Agnellus, Bishop of Fondi, whose city had been destroyed, was appointed cardinalis sacerdos of the diocese of Terracina by Pope Gregory I.

[9] The sees of Piperno[10] (Privernum) and Sezze[11] (Setia), situated on the side of the Lepinian hills, were united to Terracina, perhaps by Pope Alexander III, or even earlier.

[13] On 16 July 1725, with the Bull "Regis Pacifici", Pope Benedict XIII restored the See of Piperno and Sezze, declaring them united aeque principaliter to the diocese of Terracina.

[14] Bishop Francesco Antonio Mondelli (1805) was exiled in 1809, for refusing to take the oath of loyalty to Napoleon, following the arrest, deposition and deportation of Pope Pius VII.

Since the cathedral served as a parish church, the Archdeacon had the "cure of souls" (responsibility for the spiritual welfare of the parishioners).

The former Pontine Marshes, which had finally been drained after more than fifty years of work, were opened to agriculture, and the state sponsored a large-scale immigration from the Veneto, whose principal patron saint was Mark the Evangelist of Venice.

[23] By the papal bull of 29 April 1725, the church of S. Maria was reestablished as a cathedral and united aeque principaliter with the diocese of Terracina.

The Second Vatican Council, in order to ensure that all Catholics received proper spiritual attention, decreed the reorganization of the diocesan structure of Italy and the consolidation of small and struggling dioceses, in particular those with financial and personnel problems.

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.

In 1784, from 30 May to 1 June, Bishop Benedetto Pucilli (1775–1786) held a diocesan synod in the cathedral of Terracina, the decrees of which were published in Rome in 1885 by the Salamonian press.

An extensive report of the consultations, Perché la nostra Chiesa sia "Più-Una", was published.