Answer:
In the given passage, the author O'Brien talks about the beauty of war and describes it as beautiful, startling, majestic, and symmetrical as he wishes to throw light upon the effect that the war has on the participants. The imagery of comparing the terror of war to sublimity and beauty helps in conveying that although the war has always been terrible and wicked, the allure of war('gape') don't let people to take their eyes off it and attracts people.