A Call for Unity... but How?

In "Beat! Beat! Drums!" Whitman is playing directly on the emotions and grievances of his readers. I see this as a means to incite a broken nation to unity by banding its people together against a common malady. There is, as far as I can see, no reference in this poem to slavery or the things of slavery. Even when speaking of farmers, Whitman states, "Nor the peaceful farmer any peace [must he have], ploughing his field or gathering his grain." This does not even acknowledge the fact that farmers, at this time, had slaves plowing their fields and gathering their grain. Neely described Whitman's writing as interpreting the Civil War as a "war for Union," rather than, "a war of liberation."
Although the poem is clearly denouncing war as an acceptable means to ending the division between the north and the south, it respectively does not offer any satisfactory solutions on how to peaceably end this disunion. It never addresses the causes of the war (i.e. slavery, difference in ideals, etc..), but rather condemns the war as unacceptable. Whitman, here, is attempting to raise awareness of the atrocities of the war and, in his readers, is trying to provoke a catharsis of the inhumanity displayed by the war. It is not his goal to burrow into its causes and foundations, but rather to display in full color its negative consequences and ramifications.
Like Whitman, it seems as if Horton also strives to unveil the, "Terrors of War," rather than actually attempting to understand what adds fuel to the fire. In, "The Spectator of the Battle of Belmont," he manifests the cruelty and bloodiness of the battle and even states that a "spirit" alone can consummately convey the barbarity displayed on this battlefield. Once again, there is no solution provided or cause targeted, but rather a condemnation of the elements of the war rather than the source of its beginnings. It can be concluded then, that Neely was correct in his assertion. The atrocities of slavery are not uncovered, nor are they even mentioned in these poems. Whitman is ultimately trying to lead a war-torn nation out of a battle on ideologies without providing his followers with any viable avenues of escape.