~~Having read The Sun Also Rises as an undergrad, I was very excited to read it from a perspective of World War I and its effect on the writing of the time period.  As I read the second half of this novel, I found that there are very pronounced shifts in the structure of the story.  We get three main settings within the story: Paris, where Jake and the other ex-patriots live; the pastoral environment where Jake and Bill fish; and Spain, where they characters go to the fiesta and the bull-fights.  In the final portion of the novel, we are given a very stressful and uncomfortable environment, despite the partying aspect of the fiesta. 
 One of the first indications that the fiesta might be bringing some problematic events is at the very end of the last chapter before the fiesta begins.  Jake and his friends have already arrived at Spain and are waiting for the party to begin.  Jake tells us that “We all felt good and we felt healthy, and I felt quite friendly to Cohn.  You could not be upset about anything on a day like that” (Hemingway 155).  However, there is one final, one sentence paragraph at the end of the chapter: “That was the last day before the fiesta” (155).  Hemingway juxtaposes this short paragraph from the nice, seemingly conclusive paragraph before it.  In the second-to-last paragraph, we get discussions of the weather, the “high white clouds above the mountains,” how it is “fresh and cool on the plateau,” and how everyone is getting along fine.  Then we get the final sentence about the fiesta.  At the fiesta, everyone will be drinking constantly, and all of their natures will be brought out more dramatically because of it.  Brett’s sexual promiscuity will be more pronounced, Cohn will act even more jealous, and Michael will be more confrontational.
 One also notices a sense of foreboding by the specific language that Hemingway uses to describe the crowds of people.  I would argue that they are intentionally calling up the idea of the Great War, which ultimately caused the alcoholism that this “lost generation” is indulging in.  In the first sentence in of Chapter XV, we are told very simply that at noon the next day “the fiesta exploded” and that “[t]here is no other way to describe it” (156).  Furthermore, on page 157, Jake describes how the nice tables are taken and put away by the restaurants (because there will be so many drunken antics by the fiesta-goers), and Jake compares the café to a “battleship stripped for action” (157).  When the first rocket goes off, which announces the start of the fiesta, its smoke “hung in the sky like a shrapnel burst” (157).  Considering Jake’s war wound and the psychological trauma that was caused by it, it is almost as if he is having a “shell-shock” flashback to his time in the war.  At the very least, it calls to mind the very war that put him, his friends, and Brett onto the self-destructive paths that they expose most prominently at the fiesta itself.