I was reading this book called Miss Peregrine's Home for Peculiar Children by
Ransom Riggs and realized that part of it takes place in the time of WWII. It is about a boy who's grandfather dies. All his life Jacob (the boy) had thought
that his grandfather's spooky stories were lies - fairy tales. Then he's told that he is crazy because he saw a monster that killed
his grandfather but the police said that the death was caused by a pack of feral dogs. After some time of nagging his parents, and his psychiatrist saying it
might be good for him, Jacob and his father decide to visit the island where the grandfather spent time with the "peculiar children.". (Jacobs grandfather was evacuated to this "orphanage" as a child.) Jacob finds the school and
it is in ruins. Everybody died years ago when it was bombed by German planes. He sees a girl, chases after her, and runs into a cave/tunnel-ish thing. He travels back in time and ends up in the year 1940
on September 3rd.
In this book the school is in a loop, a day in time
that repeats over and over, and every night the planes bomb them (though they are not demolished). These "peculiar children" are using the loop as a hiding place. But just what are they hiding from?