What is the genre of the Civil War music?

Answer 1

There is no one genre of Civil War music. For convenience, I will mention two basic categories of Civil War music:

Military music: Most army and cavalry units had a band that 1) played signals to guide troop movements during battles, 2) played marches both as the unit marched from, for example, camp to the battlefield and for whatever parades the unit participated in, and 3) played to entertain members of the unit (and anyone else within earshot) and improve morale in their encampments. The bands therefore played military signals, marches, and arrangements of popular songs, dances, hymns, etc.

Popular music: Publishers of both the North and the South actively published music during the war, as they did before and after. While not everything they issued had anything to do with the war, current events always loomed large in nineteenth-century popular music. Songs comprised the majority of sheet music, but there were also lots of piano pieces. This music included 1) general patriotic music that extolled the virtues of one side's cause, 2) music in honor of a local military unit or famous military or political figure, 3) commemorations of particular battles or events--and especially the death of someone famous, 4) songs about soldiers' bravery, fear, love of home town, etc. 5) songs about dreadful conditions on the battlefield or in prison camps, 6) songs about how a soldier's mother or girlfriend missed their soldier or mourned his death, 7), comic songs to relieve tension.

As appropriate to the texts, songs might resemble marches, popular dance forms, hymns, or laments. The piano pieces might be any of these plus sets of variations on especially popular songs.

For more information, see the Civil War articles at Musicology for Everyone

Unless you meant the band "the Civil Wars". . . I would say maybe a southern rock or loose acoustic.