Why is The Boy in the Striped Pajamas a fable?

In order
to convey his moral message, Boyne departs from the conventions of historicalto tell his story
as a . This is his way of alerting the reader to the sense of unreality that pervades
.

When writing the novel, Boyne doubtless knew that he
would come in for criticism for presenting a friendship between a German boy and a concentration
camp inmate that could never have taken place in the real world. Putting the story into a fable
form is a way of heading off potential criticism as well as trying to get the reader to
concentrate on the moral messages the author wishes to convey instead of historical detail,
which, though important, is of secondary importance.

What we're left with is
a tale that certainly packs a powerful emotional punch and puts across its message with great
aplomb, but which is still recognizably a fable in that the two most important charactersBruno
and Shmuelhave an air of unreality about them.