The ironic tone of "War is Kind" is carried throughout the poem. In stanza two, Crane writes of the "men born to drill and die" with the "unexplained glory" overhead. This juxtaposition of the senselessness of the military and its training men to die for the "glory" of the country is emphasized by Crane's metaphor for the flag.
Later, in stanza four the cruelty of war, in ironic opposition to its "kindness," is underscored by the second reference to the flag as "swift" and "blazing" with an "eagle with crest of red and gold," an image that connotes the pedatory action of the bird of prey portrayed on this flag. As a symbol of the country, the flag represents the government's preying upon families as it sacrifices their sons to the "unexplained glory."
Contributing to the bitterness of the poem are these images that Crane presents, followed by the ironic commentary. His final commentary includes the image of the flag:
On the bright splendid shroud of your son [the flag now becomes a shroud]/Do not weep./War is kind!