What is the theme in Collected Poems by Wilfred Owen?

The most important theme in Owen's work is that war is usually pointless and a waste of life, waged for the pride of politicians. Even before Owen becomes an active participant in the war, he believes that it will destroy many of his generation's best minds that could have advanced civilization if they were not killed. However, before he is actually a soldier, Owen also writes that the war could cut down the population in some useful way. Once Owen becomes a soldier himself, he gains sympathy for all the soldiers involved, including ones that are supposed to be his enemy.