Having now a first working draft, I can stand back to see just what question the book is answering.
Imagine you are looking at a film about D Day and the drive through to the heart of Germany; you wonder how on earth everything got there, how the soldiers had what they needed when they needed it. That is the question.
War on Wheels tells its reader how the troops were supplied with everything apart from food and fuel. It could do this too. It tells how those many involved learnt through mistakes and experience of war.
It can tell more about the vehicles themselves: with what did the army mechanise. It can talk about who designed them, who made them and how they were used, as well as how they were supplied and maintained.