"Appomattox", an opera surrounding the events at the end of the American Civil War, was commissioned by the San Francisco Opera and premiered on October 5, 2007. As in "Waiting for the Barbarians", Glass collaborated with the writer Christopher Hampton, and as with the preceding opera and Symphony No. 8, the piece was conducted by Glass's long-time collaborator Dennis Russell Davies, who noted "in his recent operas the bass line has taken on an increasing prominence... (an) increasing use of melodic elements in the deep register, in the contrabass, the contrabassoon—he's increasingly using these sounds and these textures can be derived from using these instruments in different combinations. ... He's definitely developed more skill as an orchestrator, in his ability to conceive melodies and harmonic structures for specific instrumental groups. ... what he gives them to play is very organic and idiomatic."