During what summer does most of the action in A Separate Peace take place?
The actual storyline of A Separate Peace, after the introduction as Gene revisits Devon and looks back at his experiences, begins with Finny daring Gene, Leper, Chet, and Bobby to jump out of the tree and into the river. This was strictly off limits and forbidden to them, as underclassmen. Jumping from the tree and splashing into the river was part of the training for senior students, those being directly prepared for the war that was awaiting them as soon as they graduated. It was practice for jumping out of a damaged troop ship and splashing to push away burning oil slicks on top of the water. Gene describes the time as being "my sarcastic summer, 1942."