The Diocese of Tortosa gives a certain foundation to an ancient
historical region that, despite having no political representation, shares common historical, cultural and linguistic ties. This territory is known as
Ilercavonia in academic and scientific circles. The territory of the historical Diocese of Tortosa was greatly reduced during
General Franco's
dictatorship, following the
Concordat of 1953 between the
Francoist regime and the
Vatican. Under the pretext of adapting the dioceses to the
civil provincial limits the
Consistorial Congregation, bending to the wishes of the dictator, broke up the traditional region of the Diocese of Tortosa: • On the 2d September 1955, the
Cesaraugustanae et aliarum decree of the Consistorial Congregation was published and the following year the parishes of
Arenys de Lledó,
Calaceit,
Cretes and
Lledó d'Algars in
Matarranya, doing away with the traditional
Aragonese parishes of the Diocese of Tortosa. Meanwhile,
Betxí, an enclave of the
Diocese of Teruel, was briefly added (1956–1960) to the Diocese of Tortosa and
Maials was transferred to the
Roman Catholic Diocese of Lleida. • Following the
De mutatione finium Dioecesium Valentinae-Segorbicensis-Dertotensis decree, of 31 May 1960, the parishes of
Nules,
Vila-real,
Castelló de la Plana,
Lucena and
Albocàsser that had historically belonged to the Diocese of Tortosa were aggregated to the
Diocese of Segorbe-Castellón along with the parish of Betxí.
Francoist propaganda presented the changes as an occasion for rejoicing. ==List of bishops==