Complex sentence: The premiere was scheduled for the first anniversary of Rossini's death in 1869, but the performance was cancelled and the piece fell into oblivion until 1988, when Helmuth Rilling premiered the complete Requiem for Rossini in Stuttgart.
Split into simpler sentences: The premiere was scheduled for the first anniversary of Rossini's death in 1869, but the performance was abandoned. The piece fell into oblivion until 1988, when Helmuth Rilling premiered the complete Requiem for Rossini in Stuttgart.