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 to be broadcast in the USA, over the NBC radio network, in December 1944, by the NBC Symphony Orchestra, featuring soloists from the Metropolitan Opera (though a shortwave broadcast of one act, conducted by Toscanini, had earlier been relayed from a 16 August 1936 performance at Salzburg.) Divided into two consecutive broadcasts, the 1944 performances were later issued by RCA Victor on LPs and CDs. "Fidelio" was the first opera performed in Berlin after the end of the World War II, with the Deutsche Oper staging it under the baton of Robert Heger at the only undamaged theatre, the Theater