Duchess of Brittany, afterwards Carmelite nun, b. 1427; d. at Nantes, 4 Nov., 1485. The daughter of Louis d'Amboise, Viscount de Thouars, she was betrothed when only four years old, to Peter, second son of John V, Duke of Brittany, the marriage being solemnized when she had reached the age of fifteen. The union was, however, not very happy owing to the morose disposition of the husband who occasionally ill-treated his wife; but her gentleness gradually changed his heart, he assisted her in her works of charity and did penance for his former dissolute life. After his succession to the dukedom in 1450 her wholesome influence made itself felt in wider circles; she also intervened, not always succeessfully, in the never-ending family feuds. The duke died, leaving no legitimate heir, in l457 after having borne testimony in his last will to the devotedness of his wife. The latter consecrated her life to God, but for several years she was unable to consummate the sacrifice by entering a convent. While being educated by her future mother-in-law she had early distinguished herself by almsdeeds and fervent devotion to the Blessed Sacrament.