 Although suppressed at the time of the Napoleonic Concordat (1801), the Diocese of Belley was re-established in 1822 and took from the Archdiocese of Lyon the arrondissements of Belley, Bourg, Nantua and Trévoux, and from the Archdiocese of Chambéry the Arrondissement of Gex.Local tradition maintains that Belley was evangelized in the 2nd century by the martyrs Marcellus and Valerian, companions of St. Pothinus.The first bishop of historic certainty is Vincentius, mentioned in 552.