I think yours is a good analogy about "the trees", but I must say that I've always thought the "cause" of the Civil War was secession of the Southern states, and that the cause of secession was primarily "states' rights", which Southerners felt were most threatened by the fear of immediate abolition of the slaves and the loss of the "legal" capital they represented, the damage to the Southern economy this would cause and the fears of a morally and societally uneducated class of people released into Southern society.
Jim