"Mother" is the third word in this poem and the image of the sleeping mother, and the idea of motherhood itself (life giver, nurturer, protector) stays with us throughout the poem. Let's face it—there's not much that's more important than Mom. Without her, where would we be? In fact, without her we wouldn't be at all! Which brings us to another big element in this small poem: birth imagery. Jarrell himself said the gunner in the turret was like a child in a womb and he relies heavily on that imagery in the poem.
Line 1: "Mother" really jumps out in line one. As an idea and an image it is much more immediately recognizable in a literal sense than "the State." By putting the image and idea of mother in our minds in the poem's first line, with all the life-giving, nurturing aspects that go along with, it makes the destruction and brutality that follow seem even more horrific.
Lines 2-5: The description of the gunner in the ball turret as "hunched in [the] belly" of the bomber makes the turret into a metaphor for the womb. But it's not a nice, cozy, nurturing, safe womb like Mom's. It's freezing and dangerous, under attack from "nightmare fighters." When the gunner's remains are at last "washed […] out" of the turret, it is like a morbid rebirth. In harsh contrast to a mother birthing a child into life, the turret/womb of the bomber births the gunner into death.