In December 1862,  Whitman went to Virginia where he would care for his brother George,who had been wounded at the first battle of Fredericksburg. While George's wounds were minor, Whitman witnessed the horrific suffering of hundreds of soldiers.  Affected by these sights, Whitman volunteered to help care for wounded soldiers, and in the course of so doing, he was profoundly moved. His experiences wrought a tragic dimension to his poetry. 

In "A Sight in Camp in the Daybreak Gray and Dim," the speaker emerges from his tent to see "three forms...on stretchers lying" and he notices that blankets are spread over their bodies. With a melancholic curiosity, he lifts the blankets and discovers an elderly man, a youth cut down in the bloom of his young age, and then, in the face of another, the speaker perceives "a Christ-like" figure;that is, a man made a sacrificial victim;

Then to the third==a face nor child nor old, very calm, as of beautiful yellow white ivory;

Young man, I think I know you--I think this face is the face of Christ himself,

Dead and divine, and brother of all, and here again he lies.

The explicit message here is that Whitman, having seen the horrors of war, does not wish to dwell upon the war per se; instead, he selects from the older and younger soldiers the concept of the universality of human suffering. These two Confederate soldiers have been made Christlike in their deaths as they have become sacrificial victims for the cause of secession, and it is this meditation upon the human tragedy of war that is the part of the Civil War which Whitman feels will never be told to the public.  The poignancy of the heroism of the old and young soldiers is both beautiful and holy, Whitman tells his readers.