Wilfred Owen wrote anti-war poems based on his horrible experiences in the trenches in World War I. In this fanciful poem, the narrator, a soldier, meets the ghost of another solider. The narrator realizes they are meeting in hell. They talk, and the other soldier tells him, at the end of the poem, that he is an enemy soldier that the narrator yesterday had "jabbed and killed."
Earlier in the poem, the narrator, realizing that hell is better than the battlefield, tells this dead enemy soldier that he has nothing to mourn. The dead soldier responds rather bitterly that he does have reason to mourn: his hopes for what he could have done with his life have been destroyed. He says to the narrator:
Whatever hope is yours,
Was my life also; I went hunting wild
After the wildest beauty in the world
In other words, as he will go onto explain, the dead soldier, through his experiences of life, could have made many people laugh with "glee" and also could have made people weep. He could have told people how terrible war was if he had lived. He could have made a difference in the world. But now, because he is dead, the wild beauty of the world and the truth of war will be left "untold, / The pity of war, the pity war distilled."
In other words, even though being in hell is better than being on the battlefield, the solider has been deprived of the hope of telling his truth to the world.