O'Flaherty's message that he embeds within the story is one of futility. The sniper is so driven towards his goal of taking out the other sniper. He sees this as central to his being. The attitude that the sniper takes towards his mission is that it provides focus and meaning. He forgoes eating, and is excited about the prospect of accomplishing his goal. Meaning is seen in the act of destruction.
However, once the sniper does accomplish his goal, there is a realization as to the futility of his actions. The act in which so much drive and purpose had been placed has now been rendered as devoid of value when the sniper sees the consequences of his actions. When he further recognizes that he has serves as his brother's killer, the message that the author gives to the story becomes clear. There is a futility in war that results in only death and destruction. War is the process by which human beings become the madmen that not even the heavens could envision. There is no purpose in the destruction of war, a destruction which, at one point, carries so much purpose and relevance to it. It is in this where the message that the author gives has meaning in bringing out how elements that human beings feel meaning actually lack it.