Here's an interesting new book with an impossibly specialist title: Damn Dutch: Pennsylvania Germans at Gettysburg. It deals, through a collection of essays, with the Pennsylvania Volunteer regiments made up of native-born German speakers. And although there is a great deal of military content concerning those formations, the really interesting stuff is about the tensions between the American Pennsylvania Deutsch and German immigrants in uniform. Certainly, their politics could not be further apart, the Pennsylvanians being conservative Democrats.
I should note especially for the militarty historians, that there is a major re-examination of the 11th Corps' performance at Gettysburg in light of this distinction between "native" and "foreign" Germans.
Bottom line for these authors: the Civil War had a dis-integrating effect on society, with the Germans becoming a more inward-looking subculture as a result of the conflict.
If you see the title, have a browse.