What struck me in this section is the amount of music mentioned--the music playing during the marches and battle, the soldier's talk of music, and particularly the conversation about the bugle calls of Dan Butterfield. I didn't know that Taps originated during the Civil War.
Do kids still grow up learning the lyrics to When Johnny Comes Marching Home Again and Dixie? It was part of my education. I also recall learning about the importance of bugle calls and drum corps in earlier armies, but all of that was brought to life seeing it represented in a novel of the experience of a battle as it is being waged. You can listen to some of the songs and bugle calls on YouTube.
I felt compelled to learn a bit more about Dan Butterfield's experimentation with bugle calls and his writing of Taps. A quick search reveals that there have been disagreements over the origin and initial use of Taps. However, Jari Villanueva, a 23 year veteran of the US Air Force Band in Washington, DC and the foremost historian of military bugle calls, wrote a book about Taps. You can read an excerpt of his findings on his website.
When I finish reading The Killer Angles, in addition to watching the movie Gettysburg (1993, based on this book) I may have to finally watch Ken Burn's documentary on The Civil War (1990). I caught bits and pieces when it originally aired and remember music being a big part of that series.