Hello, Elle!
When Aby left the clearing station he was given a form to give to his officer and was told if he did not go back he would be in serious trouble.
He had what was called "shell shock" at the time, but had recovered from wounds to his neck.
He was arrested at a farm some way behind the front line.
He was one of several (10 I think) but he was the only one tried.
Yes, he was shot as an example to the others.
Aby was a Jewish lad, and the first few chapters of the book are about his family and Aby growing up.
They left Warsaw and made their way eventually to London.
From what the author gleaned from the records, Aby defended himself at the court martial, he was not represented by anyone.
This was not unusual.
It is a very good book, although the subject matter would not be to your taste, but these things happened then.
No, I have not looked at my puzzle.
May get time later.