For Esmé with Love and Squalor
The war is the driving force behind this story, and it's essential to both the events of the plot, and the emotional transformations we see here. The narrator/Sergeant X is a soldier, just as Salinger himself was, and we see how war wreaks havoc upon him as an individual being. We also see the impact of the war on people seemingly removed from it, like Esmé and Charles, whose lives were changed by the coming of war – their father was killed in North Africa. Even though this is really the story of individual human relationships, the wartime setting is central to our understanding of it.