Philosophical melancholy and delirium, by Donald W. Livingston, 1998, page 420 --
When the moral issue of slavery as part of the war effort is subtracted from the equation, we are left with the question of whether Lincoln’s war of coercion to suppress coercion was morally justified. If all states west of the Mississippi today should secede, form a western Confederacy and agree to negotiate a treaty to apportion the national debt, would the eastern states be morally justified in launching a scorched-earth war to preserve the Union? Much less was such a war justified in 1861 in a Union only seventy years old, which had been born in secession and had expanded to some ten times its size in only fifty years, in which the states were perceived as sovereign political societies, and in which secession had been invoked by every section from the beginning. The cost of the war to the North alone, as Jeffrey Hummel has argued, would have paid for the emancipation of every slave as well as forty acres and a mule.