In The Boy In The Striped Pajamas what is an example of foreshadowing?

In The Boy In The Striped Pajamas what is an example of foreshadowing?
In The Boy In The Striped Pajamas what is an example of foreshadowing?…other than Shmuel saying that the people that go on the march you don’t see again?

In The Boy In The Striped Pajamas what is an example of foreshadowing?