"Smile, Smile, Smile," written by Wilfred Owens after he returned to France in September, 1918, is lesser-known than "Dulce et Decorum Est" but conveys his visceral hatred of the British public's failure to understand the real cost of the war, which could not be calculated in pounds and shillings (i. e., dollars and cents), as well as the public's misguided attitude towards its victims, in this case, British soldiers, wounded but smiling. The immediate cause of the poem may be Owen's outrage, in October-September, 1918, when it becomes apparent that the British and its allies have rejected an offer of truce from the Austrians and Germans.
Owen frames the poem with the images of wounded soldiers, but the poem's title is an allusion to a popular British song--"Smile, Smile, Smile"--written to encourage Britain's soldiers as they go off to a war that is supposed to be short and relatively free of casualties but results in four years of grim struggle:
Smile, boys that's the style./What's the use of worrying?/It never was worthwhile./So pack up your troubles in your old kit bag/and smile, smile, smile.
This song, and others like it, became ironic in the extreme as the years went by with ever-increasing casualties so that, in some English villages, fully 30% of the men disappeared in the fields of France. From Owen's view, "Smile" is symbolic of Britain's willful ignorance of the war's cost. In modern terms, Owen's Britain would be singing, "Don't worry, be happy."
In the first few lines, for example, Owen makes it clear that Britain's eye is on monetary gains, not the welfare of its people, especially the soldiers:
Head to limp head, the sunk-eyed wounded scanned/ Yesterday's Mail ; the casualties (typed small)/And (large) Vast Booty from our Latest Haul. ((ll. 1-3)
The great irony here is that, in any society that prizes its human capital, the casualty lists should be in large and conspicuous type to remind readers of the true cost of war. Instead, the enticing headline (large) reports of some economic gain recently made, a shameful commentary when we remember who the readers are-- wounded soldiers who are too weak to hold their heads up as they read.
Shifting his focus to his government's justification for continuing the war which, by the way, is repeated to this day, Owen attacks the often used but seldom examined justification for continuing a war that has devastated the world:
Peace would do wrong to our undying dead,--/The sons we offered might regret they died/If we get nothing lasting in their stead/We must be solidly indemnified. (ll. 9-12)
These lines, unfortunately, reflect the argument, usually from those who have not done any fighting, that the dead will consider themselves ill used if something of value is not gained as the price of their deaths. Note that Owen does not comment on this sentiment: in this section of the poem, he allows the government's (and the public's) voice to speak for itself in order to show the gulf between wounded soldiers and those who happily sing them off to war, as if the cost of their deaths can be balanced by an economic benefit, which is implied by the term "indemnified."
The wounded soldiers see the irony in their situation clearly in the last third of the poem in which we read that
. . . The half-limbed readers did not chafe/But smiled at one another curiously/Like secret men who know their secret safe/ . . . . That England one by one had fled to France/Not many elsewhere now save under France. (ll. 18-23)
To the wounded soldiers, the idea that there is an England left to indemnify (make whole economically) is laughable because, in their view, England, in the form of its soldiers, is now buried under France. Owen's reference to "secret men" is meant to set off the wounded soldiers from their civilian counterparts, who could not possibly understand that the best of what England has to offer is irrevocably gone and cannot be replaced by territory or money.
The last line
How they smile! They're happy now, poor things.
carries that last of Owen's ironic voice. These civilians--whose sympathy is real--have no idea what lies behind the smile of these torn soldiers, which they assume is a smile of happiness, perhaps of comfort (as in, "I'm just happy to be here"). They fail to recognize the smile is ironic--it expresses an understanding that the civilians cannot hope to achieve.
So pack up your troubles in your old kit bag
and smile, smile, smile.