Although English poet Wilfred Owen wrote this poem in 1918, it was not published until 1920, almost two full years after his death. Like most of his poems, it deals with the trauma that soldiers continue to deal with after they have left the battlefield; the exposure he references in the poem's title is both the physical exposure to the enemy and the elements on the battlefield, and the mental anguish they are exposed to afterwards.
The Speaker of the poem finds this even more devastating when he realizes he has been exposed to so much horror with very little purpose; he feels that the war has been futile, and that so much has been lost, and nothing gained. This is a subject that Owen frequently wrote about and a view that he often expressed in his work. He was aware that this view was unpopular, both with military leaders and with the public back at home who still wanted and needed to believe in the glory and the purpose of the war, and to feel that they were sending their sons off to fight for something that would regenerate the world in some way.
Owen's views as expressed in his poems were also ironically the catalyst for Owen returning to the front towards the end of the war, when he did not have to. He wanted to be a good soldier because he did not want his views to suggest any kind of pacifism, or cowardice, both of which were looked at harshly. Owen was an outstanding solder, and was awarded the Military Cross posthumously. He was killed in action a week before the end of the war.
Despite idolizing Siegfried Sassoon, and developing a friendship with him whilst a patient at Craiglockhart Military Hospital, Owen is considered the greatest of the World War I poets, although most of his poems were published after his death.