Airman, death, World War I—we know all of this is part of "An Irish Airman Foresees His Death," which means we also know this poem is about war. Sure, there are no crazy battle scenes, or bullets whizzing through the air, or gruesome battlefield graveyards, but war is definitely here. The thing is, war in this poem is really quiet. It's like a dirty secret the speaker doesn't want to mention directly. He refers to it with words like "fight" and "guard," and describes a "cheering crowd" that seems supportive of the war effort, but for the most part war is more like a ghost. It's always here, but we just can't always see it. Scary.
Finally! This poem reveals an important, but often unnoticed, truth. Those who go to war are sometimes emotionless. They don't always hate their enemies, and they don't always love those they guard, either.
Let's face it, gang: war is really hard to talk about. This is why the speaker often talks about it indirectly.