The main events in this story are relatively few. It is full of detail and description, but only a few important things really happen.
First, an Irish Republican sniper waits on a rooftop and eats his sandwich. He considers whether it is safe to smoke. He lights his cigarette, and a gunshot whizzes past. He peeks over the parapet, and another bullet flashes by.
An armored car pulls up, and a woman talks to the man who pops out; she points toward the sniper. It is obvious that she is revealing his location to the soldier. The sniper shoots the man first and then the woman.
When he stands up to take aim, the sniper across the street shoots at him, wounding his arm. He comes up with a plan to kill the other sniper because he has to find a way to escape before morning: he pretends to be dead, dropping his hat and rifle over the side of the building. When the other sniper stands up, believing himself to be victorious, the protagonist shoots him with his revolver.
When he goes to leave, the sniper feels overcome with curiosity about the opposing sniper's identity, so he goes to look. He is shocked to see that the other sniper is actually his brother.