The People of the Crater by Andre Norton, Science Fiction, Fantasy

Six months and three days after the Peace of Shanghai was signed and the great War of 1965-1970 declared at an end by an exhausted world, a young man huddled on a park bench in New York, staring miserably at the gravel beneath his badly worn shoes. He had been trained to fill the pilot's seat in the control cabin of a fighting plane and for nothing else. The search for a niche in civilian life had cost him both health and ambition.