The sniper in this short story is left nameless because of the way in which the author seeks to universalise his experience. The pain and suffering of war, he attempts to show, is just as terrible on those who kill others as it is on those who are killed. By keeping the name of the sniper anonymous, he makes him stand for all humans who are trapped in the horrors of civil war. Note how the sniper experiences a sudden epiphany of human emotion as he watches his enemy plummet from his roof:
He became bitten by remorse. The sweat stood out in beads on his forehead. Weakened by his wound and the long summer day of fasting and watching on the roof, he revolted from the sight of the shattered mass of his dead enemy. His teeth chattered, he began to gibber to himself, cursing the war, cursing himself, cursing everybody.
Interestingly, this effectively foreshadows the discovery at the end of the story that the sniper's opponent was actually his brother. However, its main purpose is to highlight the psychological impact that being involved in warfare, particularly civil warfare where home is transformed into an arena of danger and life and death struggles, has on those who engage in it. The anonymity that the author gives to the protagonist highlights this by making the sniper's struggles universally applicable to all of us.