In Dublin Ireland in the 1950's there is a civil war going on between the Republicans and the Free Staters. On a dark cloudy night, a republican Sniper lit a cigar after eating but the sniper for the other side saw and shot at him. He thankfully missed.
The Sniper sees a woman informant, so he shoot at her, and the opposing soldier.
He got shot
The Republican Sniper pretended to be down to fool the other sniper so that he could distract him and then hit him. He shot the other sniper.
The Republican Sniper realized the other sniper was his brother.
He felt upset about everything he had done. Killing his brother showed him how he truly felt about the war in general.