And you need not show that you mind When the others come in after hunting To gobble their muffins and eggs. (3-5)
Notice the way in which these lines focus on the "others," on everybody but the soldier; they are the ones who have gone "hunting," and they are the ones who are going to eat. The soldier is here, but not really. In a way, he is almost like a ghost, alive but dead as well.
Do they matter?—those dreams from the pit? You can drink and forget and be glad. (11-12)
"Pit" (the trenches of World War I, where soldiers lived and died) makes us think of horrible living conditions, death, and the like. The word "can" is interesting, for it only suggests that forgetting is possible, not that it actually happens. But the soldier has no legs or eyes, so we're thinking he'll never be able to rid himself of his memories.
For they'll know you've fought for your country And no one will worry a bit. (14-15)
The fact that nobody will "worry a bit" suggests that other people perceive the soldier as partially dead, as a sort of non-entity. Once they realize he was once a soldier, they'll just forget about him. It seems like he's a ghost, a person who is suffering a living death.