In Per Petterson's Out Stealing Horses, World War II plays an important role in the characterization of Trond's father. The majority of the novel takes place in 1948 after the Germans have left Norway. But through a neighbor, Trond learns of his father's wartime involvement in the underground resistance movement , a movement that involved both Trond's father and the mother of his friend Jon. Their involvement in this dangerous undertaking led to their growing sexual attraction and perhaps is the reason that Trond never saw his father again after this summer.
The novel concerns Trond's coming of age. In the beautiful scenery of Norway, Trond sees both the joy and pain of living. He becomes fiercely attached to his father, his friend Jon runs away after his own brother's death, he develops an attraction for Jon's mother, he witnesses Jon's father's arm getting crushed. One lesson Trond's father teaches him when he is cutting nettles is
'You decide for yourself when it will hurt.'
This line becomes a major theme of the novel, as we see that both father and son experience much pain and tragedy in their lives, and both try to face these experiences stoically, without help, in solitude. The war serves to show the experiences that shaped Trond's father. He was heroic, risk taking, and courageous. But it left its mark on him as father and a husband. He cannot settle down to domestic life, and though he loves his son, he ultimately leaves him. Trond likewise faces his own tragedies in much the same way by withdrawing and living in solitude. After his wife dies, Trond desires no human contact--not even from his own daughter.
The war serves as an example of the suffering that is imposed on humans. It also serves to show how that suffering can be faced gracefully and heroically--that we do have control over how much that suffering will hurt.