Roman Catholic Diocese of Mariana in Corsica

In the earliest history of the diocese, Ferdinando Ughelli reports[3] the existence of a Saint Petreius, Bishop of Mariana and martyr, for whom a shrine was built by a certain Ugo Colonna of Rome, according to the Sacra Corsicae Chronica of Salvatore Vitale.

[4] Giuseppe Cappelletti points out that Vitale is the only source of the story, but that Ugo Colonna built the Cathedral, which was dedicated to the Assumption of the Virgin Mary, and that San Petreio was a different church.

[12] During the French Revolution, the National Constituent Assembly reformed the Church in France, drawing up the Civil Constitution of the Clergy (12 July 1790).

[13] All clergy were obliged to swear an oath of allegiance to the Constitution,[14] thereby effectively entering into a schism with the Papacy and the Roman Catholic Church.

When the electors of Corsica assembled, they elected Ignace-François Guasco, Provost (or Dean) of the Cathedral Chapter of Mariana as their 'Constitutional Bishop'.

In November 1801, the decision was taken by Pope Pius VII in implementing the Concordat of 1801 not to alter the situation in Corsica which had been imposed by the French Revolution.

All of the dioceses remained suppressed, with the exception of Ajaccio, which had been the center of the 'Constitutional Bishop of Corse' and which was coincidentally the birthplace of the First Consul, Napoleon Bonaparte.