When Nomenoe, in the ninth century, reduced to something like a regular organisation this half savage society of emigrants and created the Duchy of Brittany by annexing to the territory in which the Breton tongue was spoken, the Marches of Brittany, established by the Carlovingians to hold in respect the forayers of the west, he found it advisable to assimilate its religious organisation to that of the rest of the world.  He determined, therefore, that there should be bishops on the northern coast, as there were at Rennes, Nantes, and Vannes, and he accordingly converted into bishoprics the monasteries of St. Pol de Leon, Treguier, St. Brieuc, St. Malo, and Dol.  He would have liked to have had an archbishop as well and so form a separate ecclesiastical province, but, despite the well-intentioned devices employed to prove that St. Samson had been a metropolitan prelate, the grades of the Church universal were already apportioned, and the new bishoprics were perforce compelled to attach themselves to the nearest Gallo-Roman province at Tours.

The meaning of these obscure beginnings gradually faded away, and from the name of Pabu Tual, Papa Tual, found, as was reported, upon some old stained-glass windows, it was inferred that St. Tudwal had been Pope.  The explanation seemed a very simple one, for St. Tudwal, it was well known, had been to Rome, and he was so holy a man that what could be more natural than that the cardinals, when they became acquainted with him, should have selected him for the vacant See.  Such things were always happening, and the godly persons of Treguier were very proud of the pontifical reign of their patron saint.  The more reasonable ecclesiastics, however, admitted that it was no easy matter to discover among the list, of popes the pontiff who previous to his election was known as Tudwal.

In course of time a small town grew up around the bishop’s palace, but the lay town, dependent entirely upon the Church, increased very slowly.  The port failed to acquire any importance, and no wealthy trading class came into existence.  A very fine cathedral was built towards the close of the thirteenth century, and from the beginning of the seventeenth the monasteries became so numerous that they formed whole streets to themselves.  The bishop’s palace, a handsome building of the seventeenth century, and a few canons’ residences were the only houses inhabited by people of civilized habits.  In the lower part of the town, at the end of the High Street, which was flanked by several turreted buildings, were a few inns for the accommodation of the sailors.