Like his friend and admirer Emmanuel Chabrier, Édouard Lalo (1823-92) had an unorthodox musical career: he was never formally enrolled in the Paris Conservatoire, nor did he compete for the Prix de Rome, then a rite of passage for any aspiring French opera composer. Trained as a violinist, he became a chamber musician – unusual in a French musician of his generation, he liked Brahms – and his first successes, by which time he was in his fifties, were in instrumental music: the Symphonie espagnole (1874) and Rapsodie norvégienne (1878), both written for Pablo de Sarasate, and the Cello Concerto (1876). Yet he had completed a historical opera based on Schiller's tragedy Fiesque. It failed to get a prize at a government-sponsored competition in 1867 and remained unperformed until the 21st century: some of its music was recycled, for example, in the love duet in the wedding scene of Le roi d'Ys.
Lalo's interest in the folklore of Brittany was prompted by the fact that his wife, the contralto Julie de Maligny, was of Breton origin. His librettist, Édouard Blau (one of Massenet's collaborators for Werther) heard from a friend about the medieval legend of the city of Ys. Supposedly located off the bay of Douarnenez, Ys was submerged as divine punishment for the debauchery of the daughter of King Gradlon – the “roi d'Ys” of the title, though in the opera he is nameless, like the Pharaoh in Aida, and plays a very limited role. (The church bells of Ys, still ringing in the ocean, later inspired Debussy's piano prelude La cathédrale engloutie). A first version of the opera was completed in 1875 but it was turned down by both the Opéra and the Théâtre-Lyrique. Extracts were heard in concert (with Julie Lalo as Margared) but it was years later, and after the work had been thoroughly revised in 1886-7, that the Opéra-Comique, installed on the Place du Châtelet since the 1887 fire of the Salle Favart, premiered it in May 1888. The great tenor Alexandre Talazac, the first Hoffmann in Offenbach's opera and Des Grieux in Manon, sang Mylio, while Margared was Blanche Deschamps, later the first Dalila at the Paris Opera. The success was enormous, and the work remained popular at the Opéra-Comique (by then no longer reserved for works with spoken dialogue) until it was transferred to the Opéra in 1941.
Lalo, like nearly all French composers in his generation, was deeply impressed by Wagner's works; Le roi d'Ys, like many French operas of the period from Carmen to Pelléas et Mélisande, can be interpreted as a response to the challenge posed by Wagner's artistic supremacy: a clue is given in the overture, which briefly quotes the Pilgrims' Chorus from Tannhaüser. The choice of Celtic – as opposed to classical – mythology as subject may be seen as a Wagnerian gesture. The contrast between the two couples, one virtuous (Rozenn and Mylio), one guilty (Margared and Karnac) obviously recalls Lohengrin, while Margared's final leap into the ocean may also bring to mind the end of The Flying Dutchman. But these are superficial resemblances. As he himself explained in a letter to the critic Adolphe Jullien after the premiere, Lalo had toyed with the idea of couching the work as a lyric drama, with a leitmotiv-based, continuous symphonic texture and the voices blending with the orchestra. Fearing he would produce only a pale imitation, he decided instead to remain faithful to a typically French eclecticism in the tradition of Berlioz and Gounod: the work is organized in short, clearly separated numbers (arias, duets, and ensembles) while the vocal writing, rather than being subservient to broad, highly developed symphonic textures, is unabashedly melodic and lyrical. Local color is provided by citations of folk tunes in three of the choruses. By Lalo's own account, these were sung to him by his Breton wife, even though one of them, as the Lalo scholar Joël-Marie Fauquet has pointed out, was in fact from the Île-de-France rather than Brittany. The intervention of St Corentin, popular in that region, reinforces this folk quality, rooted in the French soil. At a time when Bizet, Delibes, and Massenet turned for inspiration to Spain or India, Le roi d'Ys, by contrast, comes close, as Hugh Macdonald has perceptively argued, to being a “national” opera. Next to those rather traditional features, the work, however, is not lacking in modernism and originality: these are found in the robust, rhythmic vitality of its orchestral writing; its highly personal sense of color; and perhaps above all in the emotional intensity conveyed by the part of Margared, the role Lalo had conceived for his wife, and which reminds us that this once beloved opera was itself a labor of love.