O'Flaherty was a pacifist. How does "The Sniper" support his views?
You have only to look at the ending of this brilliant and shocking story to see how it supports the views of its author. The sudden and abrupt ending, in which the protagonist realises that the enemy he has managed to vanquish is actually his brother, reveals the key theme that war is an activity that fundamentally wounds both societies as a whole and indviduals. Note for example the way that the student responds after seeing his enemy plummet from the roof and hit the floor:
The sniper looked at his enemy falling and he shuddered. The lust of battle died in him. 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.
We see here the true cost of war and the way that it impacts individuals. This description of the protagonist contrasts sharply with the picture we are given of the cold, fanatical student at the beginning of the story. War is something that kills not only our enemies, but also kills our own characters and innocence.