According to Robert Fogel (The Fourth Great Awakening & the Future of Egalitarianism) what we might call the “spiritual capital” needed to fight the Civil War originated in camp meetings in the first quarter or so of the 19th century and was then maintained and amplified in a variety of ways (including continued camp meetings). Anecdotal evidence suggests that some, perhaps many, of those meetings were biracial and involved vigorous song of the sort we associate with fundamentalist/charismatic churches, black and white. These meetings typically took place over a period of days, even a week, and generally were rural, as was most of the country.
So, farmers and villagers would hitch up a wagon, load in their families, and travel tens of miles or more to some central location and set-up camp. They then spent a week listening to vigorous preaching, participating in vigorous song, got saved, witnessed others getting saved, and discussing religion and whatever else with their fellow Christians. This is where the abstract notions of freedom and equality came down from the rational ether to become embodied in felt imperatives for living.
If these meetings had been nothing more than polite lectures followed by polite discussion they wouldn’t have had much of an effect. In fact, if that’s what they had been, very few would have attended them, because such activities required a rather refined sensibility, more refined than most farmers, artisans, and their families had in those days.
Thus, music was a major component of the engine that made these meetings work. No music, no meetings. And without those meetings, there would have been little sense among white people that slavery was evil. It’s that sentiment that drove the Abolitionist movement.
Without that movement, the South wouldn’t have had any reason to rebel. If the South hadn’t rebelled, there’d have been no Civil War. That war was fought over a cultural issue that became a political force through cultural means, camp meetings.
In this case, then, culture became a historical force of considerable power.