In chapter 6, page 73 the first 4 words "Peace had deserted Devon" what does this mean? And what does this reveal about the story line, plot, etc..?

Gene is finally back at school, without Finny who will come back later in the term; the peace of the summer session has finally been shattered by the return of the rigorous traditions of the Devon school, and the influence of the war on the students and faculty. The change of seasons also foreshadows a change in Gene's life, and in his and Finny's relationship; with the passing of time, they will not be able to regain what they had in their ideal summer together, and their relationship when Finny comes back will most definitely be changed.

Thank you