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
Fidelio a rival nobleman, Pizarro. In revenge, Pizarro has secretly imprisoned Florestan in the prison over which he is governor. Simultaneously, Pizarro has spread false rumors about Florestan's death. The warden of the prison, Rocco, has a daughter, Marzelline, and an assistant, Jaquino, who is in love with Marzelline. The faithful wife of Florestan, Leonore, suspects that her husband is still alive. Disguised as a boy, under the alias "Fidelio", she gains employment working for Rocco. As the boy Fidelio, she earns the favor of her employer, Rocco, and also the affections of his daughter Marzelline, much to Jaquino's chagrin. On