Top Ten American Civil War Songs by Stephen M. Klugewicz
A few of the union songs are examples of Christianity/religion subverted for jingoistic nationalism. Apparently the notion of American federalism had been lost from the understanding of many, such as Stephen Foster, and that probably wasn't the fault of non-British immigrants.
Not included in the list, that song by Major James Randolph, written after the war, I believe:
Sundays in Lent
3 hours ago