In 1378, a contested papal election produced a schism in the Church. All of the cardinals and much of the Church supported Cardinal Robert of Geneva, who took the name Clement VII, and who soon returned with the papal Curia to Avignon. The rest supported the Neapolitan Bartolomeo Prignano, who took the name Urban VI. Initially the Kingdom of Naples supported Pope Clement, who chose to create a new diocese at Nardò. On 15 November 1379, the new bishop, the Sicilian Matteo de Castiello, arrived in Nardò to a decidedly mixed reception. His instructions were to make the monastery of S. Maria his cathedral and residence, and he therefore removed Abbot Guglielmo from governance over the territory of Nardò. Bishop Matteo was expelled in 1401 and the diocese of the Avignon Obedience suppressed, following a change in allegiance of the Kingdom of Naples after the death of Urban VI. A new abbot was elected in the person of Antonio de Perugia, who had been Archpriest of the cathedral. Abbot Antonio died in 1406, and was succeeded by Abbot Desiderius. Desiderius died on 27 July 1412, and on 22 July Giovanni de Epifanis succeed him. On 13 January 1413, the Diocese of Nardò was established, and made immediately subject to the Holy See. The abbot of S. Maria was deposed, and S. Maria again became a cathedral. Its first bishop was appointed by Pope John XXIII on the same day. He was Giovanni de Epifanis, who had just been deposed as abbot of S. Maria di Nardò. A very great earthquake struck the area of Nardò on 5 December 1456, severely damaging the cathedral and causing the bell tower to collapse. On 20 February 1743, another major earthquake struck, bringing major damage to the Palazzo civico and the churches of S. Michele Arcangelo, S. Antonio da Padova, S. Gregorio Armeno, S. Domenico, and S. Francesco d'Assisi. In 1647, during the rebellions against Spanish rule in the Kingdom of Naples, the Count of Conversano captured Nardò and executed four of the Canons of the cathedral Chapter. The cathedral is administered by a Chapter. In 1617, the Chapter consisted of five dignities and twenthy Canons. In 1669, the Chapter was composed of six dignities and nineteen Canons. The Chapter is currently headed by the Archpriest, with seven additional Canons, one of whom is the Penitentiary. The co-cathedral of S. Agata at Gallipoli is headed by the Primicerius-Theologus, and has a Cantor and one other member.
Twentieth century changes
Following the Second Vatican Council, and in accordance with the norms laid out in the Council's decree, Christus Dominus chapter 40, the Episcopal Conference of Apulia petitioned the Holy See that Lecce be made a metropolitan and that a new ecclesiastical province be created. After wide consultations among all affected parties, Pope John Paul II issued a decree on 20 October 1980, elevating Lecce to the status of metropolitan see. He also created the new ecclesiastical province of Lecce, whose constituent bishoprics were to be: Brindisi, Otranto, Gallipoli, Nardò, Ostuno, and Uxentina-S. Mariae Leucadensis. On 18 February 1984, the Vatican and the Italian State signed a new and revised concordat, which was accompanied in the next year 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. Otherwise Nardò and Gallipoli might have shared a bishop, as the Bishop of Nardo e Gallipoli. Instead, the Vatican continued consultations which had begun under Pope John XXIII for the merging of small dioceses, especially those with personnel and financial problems, into one combined diocese. On 30 September 1986, Pope John Paul II ordered that the dioceses of Nardò and Gallipoli be merged into one diocese with one bishop, with the Latin title Dioecesis Neritonensis-Gallipolitana. The seat of the diocese was to be in Nardò, and the cathedral of Nardò was to serve as the cathedral of the merged diocese. The cathedral in Galllipoli was to become a co-cathedral, and the cathedral Chapter was to be a Capitulum Concathedralis. There was to be only one diocesan Tribunal, in Nardò, and likewise one seminary, one College of Consultors, and one Priests' Council. The territory of the new diocese was to include the territory of the former dioceses of Nardò and of Gallipoli.
