Why does the sniper revolt ''from the sight of the shattered mass of his dead enemy?"
The sniper's entire mission is to stake out a particular target. Unlike the traditional notion of war fighting where one force of men seek to meet and defeat another force, the sniper's mission and focus is singular. Once this target is gone, his mission is accomplished. The sniper accomplishes his mission, but the emotional experiences of doing so are contrary to the standard depiction of traditional warfighting:
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.
The "revolted from his enemy" is a line that reflects the sense of disgust that exists in the sniper. He is fundamentally disgusted by the "mass of his dead enemy" as well as the basic premise of his being. The sniper does not experience the liberation of triumph or even the joy of vanquishing a foe. It is a hollow and empty experience in which his entire being is predicated upon negation of another. The "shattered mass" of his dead enemy is a revelation, almost an epiphany, about the hollowness of his own life. It is one in which the sniper recognizes the futility of his being in the world. This is why the sniper throws his weapon down with an oath. This oath is linked to repudiating a life in which he must confront another "shattered mass" that he has helped to create.