Franz Schubert composed about an hour of incidental music for Helmina von Chézy's play Rosamunde. The play itself is lost, however, which might be just as well, if it is as incomprehensible as von Chézy's libretto for Carl Maria von Weber's opera Euryanthe. Schubert's music was nearly lost too, and it owes its survival, at least in part, to George Grove and Arthur Sullivan (the latter of Gilbert and Sullivan fame.) Even so, ambiguities remain. There is no Rosamunde overture per se; when the play was produced, Schubert's overture to the unrelated Alfonso und Estrella was used instead, at his suggestion. He apparently came to refer to it as the Rosamunde overture. However, shortly before his death, the incidental music to Rosamunde was published in a version for piano duet, and the overture to Die Zauberharfe (The Magic Harp) was published as its overture... Schubert composed ten numbers, but the popularity of the Entr'acte #3 and the Ballet #2 overshadows the rest of them, particularly because the theme of the former appears in other works by Schubert.
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http://www.classical.net/music/recs/.../red00132a.php