"The Sniper" reveals much about the power of war. It is a narcotic, enabling the individual be lulled into a false sense of security. Consider how the Sniper is initially described in the exposition of the story:
On a rooftop near O'Connell Bridge, a Republican sniper lay watching. Beside him lay his rifle and over his shoulders was slung a pair of field glasses. His face was the face of a student, thin and ascetic, but his eyes had the cold gleam of the fanatic. They were deep and thoughtful, the eyes of a man who is used to looking at death.
The sniper is able to take refuge in the power of war. This enables him to embrace the life of an "ascetic" whose eyes hold the "cold gleam of the fanatic." War has transformed the sniper to "looking at death" and forgoing all else.
When the sniper "accomplishes his mission," the power of war is shown to course through his very being in the world. For a moment, there is a sense of totality because of "mission accomplished:" "Then when the smoke cleared, he peered across and uttered a cry of joy." The power of war is shown as a condition that enables the sniper to feel "joy" at another's "agony." This power of war is shown to be fleeting, as the sniper engages in recollection about what he has done and the cost that resulted from it. It is in the ending when the sniper realizes how much of a narcotic the power of war actually is.