The Saint-Yves portal of the west façade of the cathedral of Nantes, which is unusual both because of its location and size, provides evidence for the complex political situation surrounding the rector of Trédrez at the end of the Middle Ages in Brittany. Far from being the Breton extolled in the historiography of the seventeenth and eighteenth centuries, a characterization which authors of the beginning of the twentieth century continued, the saint of Kermartin was, on the contrary, imported into the duchy by the Montforts (at the head of which was, of course, Jean V), who appropriated the practices of the Capetian monarchs. The specific context of Brittany in the fourteenth century, on the one hand, and the primary role of Charles de Blois in the success of his canonization, on the other, provide an explanation for the political investment which was made in Saint Yves. Almost exactly a century after the canonization of the saint, the cycle of Nantes, located at the eastern most point of the duchy, illustrates this rehabilitation of the saint. Saint Yves had to make a detour through Capetian politics in order that Jean V could make him a Breton saint.