What is the authors purpose of writing war wall?

It seems you're asking about the purpose of a book titled "War Wall". However, there is no known book with that exact title. Perhaps you're thinking of a different book or have a typo in the title?

To help me understand your request better, could you please provide more details? For example:

* Is there a specific author you're thinking of?

* What genre is the book?

* Do you have any other information about the book, like a plot summary or characters?

Once I have more information, I can better understand your question and give you a helpful answer.