The novel is set during the 1940's, when young men would be constantly aware of the changes WWII was bringing to the country, including the looming reality of the draft. It's also important to remember that patriotism was running high during this time, and many young men were eager to enlist. So, Leper's story would be representative of some soldiers' experiences during this time. In the novel, Leper is drawn to enlist by a propaganda film of soldiers on skis. Not only does it speak directly to Leper's passion, but everything looks clean and the soldiers seem to work together as a coherent unit. However, once he goes to boot camp, Leper realizes that the reality is nothing like the film. He suffers a mental breakdown, hallucinating and eventually going AWOL. While not the norm, many soldiers did suffer a crisis of philosophy after joining, when their illusions about the realities of war were shattered.
Closely connected to this, the training regiment the seniors must follow reflects the truth of their situation in the mid-1940s. Gene often notes the mostly physical education the seniors are receiving, to the detriment of their other studies. This was common at the time, since the goal was to prepare as many men as possible for the war. Later, actual recruiters come on campus, and the Army uses the school for training and exercises. This too would be an actual occurrence during the war.
Finally, the pressure Gene feels to succeed in his academic classes, while maintaining some measure of athleticism, would be common for boys attending private prep schools during this time. These schools were considered the best education a boy could receive, and academic success would nearly guarantee acceptance to a high-level university. While most of the students at prep schools didn't push their best friends out of trees, many experienced the same pressure and anxiety as Gene to achieve in school.