Futility means that something is destined to fail. The quality of producing no valuable effect, or of coming to nothing; uselessness. The structure of the poem is in balanced stanzas - the tenderness and hopefulness at the beginning; the growing bitterness of the second, with its climax. Owen is telling the persona's story of the death of a comrade as a balance. This has to happen as so many of them died that there still has to be a degree of sanity left in them.
"Futility" mourns the sad ironic death of a soldier, a young man in a young body. An address to the sun, which gave the life to the earth and its inhabitants only for them to be cut down in this futile way, states a larger, more universal irony. The 'futility' of the poem concerns this death and all life in which such death occurs.
The persona of the poem hopes that the sun will revive the dead one, as it had formerly stirred him whilst he was at home in England. The sun builds a contrast between the dead man's life earlier in England and his death now in France. Owen makes the persona question if the sun can start life, why can't it bring it back? The poem moves to the bitterness of the recognition of the 'futility' of life, i.e. "dear achieved."
The theme in this poem is the pointlessness of human sacrifice and indeed, of life itself. The poem is also relevant to larger issues of human existence. He challenges the rhetoric of the nobility of war-service, and giving one's life for their country. The tone of 'futility' conveys the sense of a lament (mourning) for the dead one, tenderly, at the beginning, and intensifies to bitterness...