Complex sentence: During 1869, twelve other famous Italian composers of the time also collaborated, the premiere having been scheduled for 13 November, the first anniversary of Rossini's death, but on 4 November, nine days beforehand, the organising committee abandoned it.
Split into simpler sentences: During 1869, twelve other famous Italian composers of the time collaborated, the premiere scheduled for 13 November 1869 on the first anniversary of Rossini's death. But on 4 November, nine days beforehand, the organising committee abandoned it.