"The Sniper" is about a young man fighting in the Irish Civil War. The story illustrates how a young, impressionable person can become used to the atrocities of war. However, after the sniper is able to kill the enemy sniper, he suddenly becomes human again and is filled with remorse.
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.
In his disgust, the sniper throws his revolver and it goes off, scaring him back into a more focused, soldier's mentality. Seeing that the coast was clear, the sniper decides to get a look at his enemy, thinking he might know him, maybe before the army split into Republicans and Free Staters. The final line can be read literally or metaphorically:
Then the sniper turned over the dead body and looked into his brother's face.
Given that this was a civil war, he could have been looking into his actual brother's face. Or, brother could mean fellow Irishman; therefore, he was looking into the face of a fellow countryman. (The American Civil War was often called a battle of "brother against brother.") In any case, this shows, regardless of the reasons for war, how senseless war can be. A civil war is more prone to be personal because a soldier might know, or even be related to, some of his enemies. But even in an international war, we could say that a man shooting another man is shooting his brother since we are all human and related in our desire to live peacefully.