19 November - Gurguy, or Tanguy is the son of Galonus, lord of Trémazan, on his first wedding day. Galonus went to look for a new wife, but this woman ruddered and mistreated the children like a real stepmother for eight years. Gurguy, already grown up, asked his father for leave and went to the court of King Childebert, where he stayed for twelve years.
Haude, Gurguy's sister, was determined, for God's sake, to put up with her stepmother, who hated her for her virtue and piety. She gave her chores, but Haude obeyed, and prayed at night if her chores prevented her from attending mass. She took from her ordinary life to give to the poor. Gurguy was thought to be dead, and Haude became a good match because she was beautiful but also heiress of great possessions. Lords came to propose to her, but the stepmother, jealous, spoke ill of Haude and exiled him to a neighbouring farm. Gurguy then returned incognito to Trémazan and was surprised by the absence of his sister. The stepmother, believing him to be a suitor, told him that Haude was a lost girl.
Gurguy, believing these slanders, sought out his sister, and having found her near a fountain, called her by name. Haude did not recognise her brother, who had been gone for a long time, became frightened and ran away. Gurguy took the flight as an admission of shame for his misbehaviour and, angry, cut off his head. But neighbours told him how wise and virtuous Haude was, and when Gurguy realised his mistake, he went to his father's house, was recognised and confessed his crime. Haude came to him, holding his head in her hands, and she put it on his neck where she rested it. Haude turned to his stepmother and told her that she would be punished by God. Then she turned to her brother and told him that Our Lady had obtained his forgiveness. Haude also forgave her brother and died on the 18th of November in the year 545.
Gurguy went to Saint Pol Aurelian, Bishop of Leon, who ordered him to fast for forty days. Then he changed his name to Tanguy and appointed him abbot of Gerber. Tanguy had received from his father a piece of land at the tip of Cape Pennarbed (Finistère), near which a ship carrying the relics of Saint-Matthieu was miraculously saved from sinking and the cape was called Loc-Mazhé-Traon (Mazhé = Mathieu in Breton, thus Pointe Saint-Mathieu). Tanguy built a monastery there and Saint Pol appointed him abbot. He died on 12 March 594, the same day as Saint Pol Aurélien at Batz. He was buried in Loc-Mazhé (Saint-Mathieu). Saint Tanguy is highly revered in Brittany.