It's propaganda by leitmotif!

Third Republic composers were keenly aware of the value of projecting patriotic images. This can be seen both in their compositions and in the image making they cultivated in the rapidly expanding press from the 1880s up to World War I. Works range from Augusta Holmès's Ode triomphale (1889) and Hymne à la Paix (1890), written for the Paris exhibition of the same year, through Raoul Pugno's “mime drama” Pour le Drapeau (1895), to Théodore Dubois's Symphonie française (1908). The most ambitious expression of republican patriotism, however, was Émile Zola and Alfred Bruneau's Messidor (1896), first performed at the Paris Opéra in 1897 and aptly named after the harvest month in the French revolutionary calendar.

Zola and Bruneau met in 1888 in the salon of architect and littérateur Frantz Jourdain. Bruneau's first opera, Kérim, had been performed by the Théâtre-Lyrique the previous year. Collaboration with Zola—whose famous novels had never been set as opera—was the greatest coup of Bruneau's career. The first fruits were Le Rêve (1891) and L’Attaque du moulin (1893) at the Opéra-Comique, adapted into verse by veteran librettist Louis Gallet. These successes convinced Zola that opera was capable of serious social and political comment; he also shared Bruneau's vision of opera, which would be musically and dramatically avant-garde, demonstrably republican, and distinctly French.

Messidor, begun in 1893, was Zola's first libretto, but not his first theatrical work. His reputation as a novelist obscures his plays Les Héritiers Rabourdin (1874) and Le Bouton de Rose (1878). William Busnach dramatized the most celebrated—and notorious—of Zola's Les Rougon-Macquart novels, including L’Assommoir (1879), Nana (1881), and Germinal (1888), the last causing a scandal and banned in 1885. Zola novels also proved ideal for André Antoine's naturalist Théâtre-libre from its foundation in 1887.

Messidor drew on the social radicalism of Germinal. While sanitizing Germinal's violence and sexual imagery for the Opéra audience, Messidor remained a revolutionary “drame social” of artistic innovation and political critique. Just when Wagner's works were establishing themselves on the Paris stage, Messidor made free use of what were, for the audience, novel musical and dramatic techniques.