TL;DR: – A March in the Ranks Hard-Prest and the Road Unknown

A route through a heavy wood with muffled steps in the darkness, Our army foil’d with loss severe, and the sullen remnant retreating, Till after midnight glimmer upon us the lights of a dim-lighted building,The army of the narrator retreats after their loss. Are these Union men? Are these confederate men? Does it matter? Their march takes them well into the night, past midnight until they come upon an old church.
We come to an open space in the woods, and halt by the dim-lighted building, ‘Tis a large old church at the crossing roads, now an impromptu hospital, Entering but for a minute I see a sight beyond all the pictures and poems ever made, Shadows of deepest, deepest black, just lit by moving candles and lamps,The church has been made a hospital, and the man sees something that nothing in the world could every compare to.
And by one great pitchy torch stationary with wild red flame and clouds of smoke, By these, crowds, groups of forms vaguely I see on the floor, some in the pews laid down,Men in pews, men on the floors. Men dying.
At my feet more distinctly a soldier, a mere lad, in danger of bleeding to death, (he is shot in the abdomen,) I staunch the blood temporarily, (the youngster’s face is white as a lily,) A mere lad. A mere lad is dying at our unnamed narrator’s feet, and though the narrator knows that the young boy will die he helps him nonetheless.
Then before I depart I sweep my eyes o’er the scene fain to absorb it all, Faces, varieties, postures beyond description, most in obscurity, some of them dead, Surgeons operating, attendants holding lights, the smell of ether, the odor of blood, The crowd, O the crowd of the bloody forms, the yard outside also fill’d, Some on the bare ground, some on planks or stretchers, some in the death-spasm sweating
An occasional scream or cry, the doctor’s shouted orders or calls, The glisten of the little steel instruments catching the glint of the torches,
The march must resume so the man takes one last look. The horror, the blood, and the gore, he takes it all in. Men are dying; and though our narrator is a soldier fresh from a lost battle this scene strikes him with horror.
These I resume as I chant, I see again the forms, I smell the odor, Then hear outside the orders given, Fall in, my men, fall in; But first I bend to the dying lad, his eyes open, a half-smile gives he me,
Then the eyes close, calmly close, and I speed forth to the darkness, Resuming, marching, ever in darkness marching, on in the ranks, The unknown road still marching
Whitman uses such keen detail and such plain wording to really encapsulate the true powerful terrifying horror of how these hospitals were.
And though they there is no rest at this holy place tarnished by the blood of men, the soldiers must keep moving on, moving ever on.