Édouard Lalo
"Le roi d'Ys", an opera by the French composer Édouard Lalo which premiered in 1888, transforms the story significantly, replacing the figure of Dahut with Margared, whose motive for opening the gates (with the aid of her own betrothed Karnac) is her jealousy at her sister Rozenn's marriage to Mylio (characters who are also inventions of Lalo).