The problem with American Civil War, as opposed to WW1, songs is that as well as think we know the songs, we don't really since there were (obviously) no contemporary recordings. Which means, not unlike classical music, there is no template. Except classical music was scored and scored to be played as scored and except for Marches, American Civil War songs were not.The Confederates lost the war but they had the songs and one reason is that the Unions had the love of a true cause and the Confederates and the love of land.
Dixie – The one song uber-alles to reflect the Deep South written by Dan Emmett -the man who invented Black Minstrel-y, really a Banjo tune which expanded into the orchestrated almost song of praise we know at the moment.
When Johnny Comes Marching Home – With a heavy marshall beat, and based on an Irish antiwar song, this is written to be marched to and the beat is tough but if the edge of anger is there, it is actual a joyous song about the end of war.
Johnny Browns Body – I remember this song from when I was a kid,, we would change the lyric to dirty ones! This is an abolitionist tale though it has been written and rewritten so often that part seems lost in time. Now it is some form of Spiritual text. Kinda like "Joe Hill" without The Union substituting for Union.
The Yellow Rose Of Texas – A banjo driven song with a nice little metaphor, the flowers of one State are referring to the fairer sex and to the State as a woman (it beats "the Belle of Tennessee"). A sweet love song -sung by a soldier at war (I think!)
Johnny Is My Darling – A Union folk song and probably a call to enlist (enlist, ha!), this is a catchy WW1 type extraction of sex and war
The Battle Cry Of Freedom – The art of the war song is lost on us today now the romance of war has been so thoroughly debunked. Rally round the flag seems an archaic concept, doesn't it? 150 years ago.