It seems like ‘A Separate Peace’ is still read often in 9th grade, but ‘Peace Breaks Out’ is apparently pretty routinely ignored. That’s too bad, as Knowles was certainly trying to settle some scores 22 years after his first and most successful novel carved out its spot on syllabi and in the boarding school mythology. I agree with the contentions that the latter book is more than a little forced in plot and characterization, but there are a few really excellent points in the novel–and being less than 200 pages, it will only take another day to get through it. Knowles was not the same man in the 70s as in the 50s and his perspective on many thing had obviously changed, including Exeter. (Like Salinger, Knowles seemingly thought he was Scott Fitzgerald and was sorta bummed when he finally acknowledged reality had smothered his pretension, making this return to his authorial glory a worthwhile trifle for readers and fans of his first book.)
Both books are especially fun for the middle-school student seriously considering boarding school. My kid read both books in 5th grade (or 6th?) back to back in less than a week during the school year. To kids born in 21st century, the guys in the first book are totally in love, and the behaviour of the adults in the second book is offensive and unbelievable. If your kid has ‘A Separate Peace’ in class or any interest in reading it on their own before high school, toss in ‘Peace Breaks Out’ in the mix for fun–and when the kid is done, read 'em both yourself if you haven’t and be glad things have changed a little bit at boarding schools.
Fwiw, my paperback copy of ‘A Separate Peace’ purchased for a class in 9th grade is still intact, but the paperback of ‘Peace Breaks Out’ purchased at the same time pretty much disintegrated over the years. I guess even the publisher didn’t think much of the later book.