The Sun Also Rises contains crucial themes relating to the experiences of several individuals living in Paris and other European locations post-World War I. While much of the story seems to be avoiding the war, suppressing its specific memory by drinking, joking, or participating in escalating, adrenaline-filled occupations so as to not remain “bored,” there are a few direct references to the war that seem to be very poignant, if understated (in the way they are presented in the text).
In one conversation between Cohn and Jake, they start talking about Brett. Cohn is obviously in love with her at this time and wants to find out more about her. Curiously, through this scene, he seems to learn more about her than he expected, and her ‘true self’ is caught up in her experiences of the war.  Jake starts:

 “She was a V.A.D. in a hospital [he] was in during the war”
“She must have been just a kid then.”
“She’s thirty-four now.”
“When did she marry Ashley?”
“During the war. Her own true love had just kicked off with the dysentery.”
“You talk sort of bitter.”
“Sorry. I didn’t mean to. I was just trying to give you the facts.”
“I don’t believe she would marry anybody she didn’t love.”
“Well,” I said. “She’s done it twice” (46-47)

The fact that Jake knows Brett so well seems to go hand in hand with the fact that they shared war experiences. We’ve talked before about how soldiers often feel that they can’t relate to people who did not go to war with them, and there seems to be some element of that here. The reason that Jake knows Brett so well is that they were together at the war hospital, and the reason that Cohn cannot really know Brett, may be because he has not experienced this crucial life experience.

This scene is also particularly striking because Brett’s situation is one we’ve encountered previously in Brittain’s work, the idea that a woman who lost the one she truly loved in the war would right away marry the first ‘good offer’ that came her way in order to avoid dealing with the overwhelming loss and loneliness that resulted from her loved one’s death. Her situation is largely pragmatic, as seems to be her impending marriage to Michael, but it is understandable given her circumstances. Within this passage also seems to be contrasting views of love. One the one hand, Cohn is a romantic who believes in true love, that people marry for love, and that Brett would never consider not marrying for love. He projects his own notions of romantic love onto Brett, ignoring the reality that Jake is trying to convey to him. For Cohn, pragmatic love sounds bitter (admittedly, part of the perceived bitterness could be from how Jake is conversing, but I think that Cohn senses a bitterness in the message as well, and not just the way that Jake is narrating).  It is bitter, but it is an understandable result of her war experience. On the other hand, Brett has married twice (to someone she presumably, according to Jake) didn’t love, and she is about to marry again, as soon as her divorce is finalized. It seems that being with men, whether it be her husband, Jake, Cohn, or others, is another way for Brett (only a “kid” during the war) to cope with her experiences and to repress them, in the same way that others use alcohol to numb their pain and remembrance.  This passage really speaks to the types of changes going on post-war as well as the shift in values, priorities, and the ways that people coped with such a horrifying life experience.