The main character in this poem is Whitman himself, who is the narrator describing his experiences nursing the wounded in the Civil War. The poem details his journey from being a man who wanted war ("I’d thought to beat the alarum, and urge relentless war") to becoming a nurse to the wounded who sees the evils and suffering that the war brings.

In the first stanza, young men and women ask him about his previous experiences in the war. Then, the narrator discusses his earlier work among the wounded. The other characters are the soldiers he recalls having nursed, along with an attendant who follows along with him to collect the bloodied rags he uses. The narrator recalls a cavalry man with such a bad neck wound that the narrator prays for the soldier's merciful death. He also nurses a soldier whose hand has had to be amputated. The wounded he nurses are important characters in this poem, as the narrator recalls his experiences in the war hospitals. The public is also a character in this poem, as the poet writes that the world has moved on from the battles and does not remember them, while he still recalls his sad and painful experiences in the war.