Issac Rosenberg's poem Break of Day in the Trenches is one which plays back and forth with the idea of life and death. Given that one only goes into a trench when at war, the poem speaks very heavily about the death.
The narrator of the poem seems relatively perplexed about how a mere rat can survive amidst a war while men, much stronger than the rat, die. The curious nature of the poem is the interplay between both life and death and the narrator and the rat.
That being said, the poem brings into question the fine line between life and death and how war simply seems to be a massive slaughter of mankind. No one is safe in war, not even the dead (given the rat can eat them). The poet offers a suggestion of humor (by speaking to the rat) and a glimpse into his own psyche/humanity (by not killing the rat) Therefore, the poem's message revolves around the fact that, in war, a person (a soldier) must be able to hold true to their values in order to survive in both war and life.