Like much else in Beethoven's career, the opera involved considerable struggle on the composer's part, and it went through several versions before achieving full success. It was first produced in a three act version in Vienna on November 20, 1805. It was subsequently condensed to two acts by Breuning, at which time Beethoven wrote a new overture (Leonore no. 3). In this form the opera was first performed on March 29, 1806 under the title "Leonore," but was again revised by Georg Friedrich Treitschke (text) and Beethoven (music) in 1814. It is this last version, first performed on May 23, 1814 with the title Fidelio, that achieved a great success in its day and has been a central element of the operatic repertory ever since.
The opera is a central work of Beethoven's so-called "middle period," and like much of Beethoven's music of this time it emphasizes heroism and the struggle for liberty. There can be little doubt that Beethoven was attracted to Bouilly's story because of the opportunity it offered to set these ideas and feelings to music.
As elsewhere in Beethoven's vocal music, the music is not especially kindly to the singers. The principal parts of Leonore and Florestan, in particular, require great vocal skill in order to project the necessary intensity without screaming or shouting, and top performances in these roles attract admiration.
Some notable moments in the opera include the Prisoner's Chorus, an ode to freedom sung by a chorus of political prisoners, Florestan's hallucinating vision of Leonore come as an angel to rescue him, and the highly melodramatic scene in which the rescue finally takes place. The finale achieves great intensity by alternating soloists and chorus, thus anticipating similar passages in the Ninth Symphony.
Beethoven struggled to produce an appropriate overture for Fidelio, and ultimately went through four versions. His first attempt, for the 1805 premiere, is believed to have been the overture now known as Leonora no. 2. Beethoven then focused and intensified this version for the performances of 1806, creating Leonora no. 3. The latter is considered by many listeners as the greatest of the four overtures, but as an intensely dramatic, full-scale symphonic movement in sonata form it had the defect of overwhelming the (rather light) initial scenes of the opera. Beethoven accordingly experimented with cutting it back somewhat, for a planned 1807 performance in Prague; this is believed to be the version now called Leonore no. 1. Finally, for the 1814 revival Beethoven began anew, and with fresh musical material wrote what we now know as the Fidelio overture. As this somewhat lighter overture seems to work best of the four as a start to the opera, Beethoven's final intentions are generally respected in contemporary productions.
Conductors of Fidelio who yearn to include the music of Leonore no. 3 has sometimes performed it between the two scenes of the second act. In this location, it acts as a kind of musical reprise of the rescue scene that has just taken place. The Overtures to Fidelio