Opera in German such as opera seria. Some Baroque composers, such as Reinhard Keiser, did try to challenge Italian dominance, and the theatre principal Abel Seyler became an eager promoter of German opera in the 1770s, but it was only with the appearance of Mozart that a lasting tradition of serious German-language opera was established. Mozart took the simple, popular genre of "Singspiel" and turned it into something far more sophisticated. Beethoven followed his example with the idealistic "Fidelio"; and with "Der Freischütz" of 1821, Weber established a uniquely German form of opera under the influence of Romanticism. Weber's innovations were eclipsed by
Rescue opera to "Fidelio" is Rossini's "Torvaldo e Dorliska" of 1815. Bedřich Smetana's "Dalibor" (1868), which contains no spoken dialogue and which bears marks of Wagnerian influence, has nonetheless been called a rescue opera, in part because of its political themes. Rescue opera was primarily a product of the French Revolution. The social changes of the period meant that opera must now appeal to the masses, and post-aristocratic, patriotic, idealistic themes—such as resistance to oppression, secularism, the political power of individuals and of people working together, and fundamental changes to the status quo—were popular. The Terror influenced stories of fear and imprisonment;