Introduction to Act II [of 1805 version of Leonore], WoO 2b
This brief piece entitled "Introduzione del IIo Atto" was long thought to be a companion piece to WoO 2a, the Triumphal March, from Tarpeja by Christian Kuffner. However, Clemens Brenneis has demonstrated through the paper watermarks and other evidence that this piece actually belongs to the first version of Leonore by Beethoven in 1805, which had three acts. It became superfluous when acts 1 and 2 were joined together in the 1806-version. (Cf Brenneis "Beethovens 'Intoduzione del IIdo Atto' und die 'Leonore' von 1805", Beitraege zur Musikwissenschaft 32, no.3, 1990).
While working on the 1805-Leonore, Beethoven's idea was an opera in 2 acts (following Bouilly and Gaveaux). However, during the rehearsals in October 1805 it became clear that the first act had become far too long. This was partly because there were 11 numbers in Sonnleithner's reworking of the libretto, against only 7 in Bouilly's original book. In an act of desperation the first act was split in two, after the Terzet "Gut, Soenchen, gut" and just before the first appearance of Pizarro on the stage.
A result of the split, which was not thought through, was a first act with hardly any action or tension. This may also have contributed to the failure of the premiere in November 1805.
Beethoven had to compose the introduction to the newly created second act very quickly. From the point of view of dramatic needs, the music of the "Introduzione del IIdo Atto" fits in very well at this particular moment in the opera. It introduces Don Pizarro by showing him only in his outward power and authority, but deliberately not revealing his dangerous malice. Thus the dramatic impact of his aria, which will follow shortly, is not destroyed by this Introduction.