How does War motivate the characters?

Throughout Gene's schooling, war threatens to break in and destroy the fragile peace of the school. The summer session represents the height of peace, as nothing, except for Finny's accident, was able to interrupt the carefree joy of those days. But, as the fall session begins, war slowly begins to encroach on the boys and motivate them in different directions. They start their "physical hardening" at the school, recruitment officers start to come around, and the boys begin to talk about enlistment and the draft. The divide between peace and war is also representative of the gap between childhood and adulthood; while peace holds out, the boys are free to be oblivious of the outside world, and are weighed down by nothing. But, when they are finally confronted by the war, they have to grow up; the strain changes them from children into adults, and obliterates the peace of their youth.