The monk, having been expelled from Jumièges, established the monastery of the Black Benedictines on the Isle of Her (Noirmoutiers) around 674, of which Luçon was at first a dependency, probably as a priory.

[5] During the administration of Bishop Elias Martineau (1421–1424), trouble came to the diocese of Luçon in the person of Georges de la Trémoille (1385–1446), the future favorite of King Charles VII.

On the same day he ordered that the churches of the Benedictine monasteries in the towns of Luçon and Maillezais should become the cathedrals of the new dioceses, in perpetuam.

In Luçon the church was dedicated to the Virgin Mary, and the monks of the monastery provided the clergy of the Chapter of the cathedral, down to 1468.

[15] All Cathedral Chapters were dissolved by order of the National Constituent Assembly in 1790, and their property and incomes directed to "the good of the people".

[17] The diocese of Luçon was abolished during the French Revolution by the Legislative Assembly, under the Civil Constitution of the Clergy (1790).

The Civil Constitution mandated that bishops be elected by the citizens of each 'département',[19] which immediately raised the most severe canonical questions, since the electors did not need to be Catholics and the approval of the Pope was not only not required, but actually forbidden.

Erection of new dioceses and transfer of bishops, moreover, was not canonically in the competence of civil authorities or of the Church in France.

The legitimate bishop of Luçon, Marie-Charles-Isidore de Mercy, refused to take the oath, and therefore the episcopal seat was declared vacant.

He was in fact one of the thirty bishops who subscribed to the Exposition des principes, sur la Constitution civile du Clergé (30 October 1790).

He resigned in 1793, in time to avoid the anti-revolutionary rising of the Vendée and the retaliation of the Terror, and obtained a post in the civil administration.

Once the Concordat of 1801 with First Consul N. Bonaparte went into effect, Pius VII was able to issue the appropriate bulls to restore many of the dioceses and to regulate their boundaries, most of which corresponded closely to the new 'départements'.

In 1848 the Minister of Public Instruction, M. Marie-Louis Pierre Felix Esquirou de Parieu, had appointed to a teaching position in the collège in Luçon a Jewish professor.

[24] In 1852 he had published a pastoral letter supporting the Index of Prohibited Books,[25] which was a challenge to the opinions of, among others, Senator Gustave Rouland, the incoming Minister of Public Instruction and Cults.

On 11 March 1856, in his capacity as a Senator, Rouland gave a speech in favor of Gallicanism and against the Index, emphasizing the policies of which Baillès was such a vocal critic.

The bishop was offered a titular archbishopric by the Pope, but he preferred to call himself ancien évêque de Luçon.