What feelings about the war were the boys hiding while they made jokes about Leper's imaginary exploits??

When the boy least likely to go to war is the first of the class to enlist in the service, it makes a big impression on Gene. Leper makes the point that "everything has to evolve or else it perishes," and this point makes Gene think of how this peace carried over from the summer could change, or how he will be forced to change in order to get by (117). This one line from Leper is delivered in such a decisive, dramatic way that it jumps out of the prose, and seems to be introducing an important new thread in the book. The boy's jokes ring hollow exposing their own secret fears and terrors about going to war.