The first is really the third
The first Leonore Overture op. 138 was only discovered in Beethoven's estate. Not only the reason for the composition but also its origins remain in the dark. By examining the sources and analyzing the music, scholars (particularly Alan Tyson) can now prove that "Leonore I" is not the first of the three Leonore overtures, but rather the third. It was composed in 1807 probably for a performance which was planned in Prague. The autograph score has been lost. This corrected copy is the only authentic source of the work. The Viennese publisher Tobias Haslinger, who acquired it after Beethoven's death, published the first printed score in 1838. It was he who gave it the opus number 138 (continuing the series of opus numbers of Beethoven's works published up to then) and the incorrect date, 1805. The usual numbering of the overtures has until today been based on this date. (After Helga Lühning, exhibition catalogue, Bonn 1997.)
