What Was the Resolution in the Short Story "The Sniper"?

At the end of Liam O'Flaherty's story "The Sniper," the titular sniper attempts to escape enemy gunfire. He throws himself on the ground next to the body of the man he kills and realizes that it is his brother.

The sniper, a member of the Republican Army, waits on a rooftop in Dublin. He is charged with killing an enemy sniper, though that is all he knows about the man. Twice the sniper gives away his position, and the enemy sniper takes advantage of this and shoots at and injures the sniper. Though hurt, the sniper respects the enemy sniper's skill but knows he must carry out his mission.

The sniper's plan to trick the enemy sniper seems foolproof. He puts his cap on his rifle's muzzle and pushes the rifle up so that the enemy sniper can see the cap. The enemy sniper shoots and hits the cap. The sniper dangles the hand holding the rifle over the edge of the roof and drops the rifle, effectively playing dead.

The enemy sniper stands, giving the sniper a clear shot. The sniper takes the shot, hits the enemy sniper and watches him fall to the street and lie still. The sniper feels remorse for killing such a skilled man but plots his escape from the roof. He knows other enemies wait nearby and will likely kill him. Making a run for it, he draws enemy fire and hides by the body of the enemy sniper, where he discovers the man's identity.