The material is not new, but the author has marshalled her extremely complex material in a cogent way and on the whole writes quite well. There are a very few shocking lapses - she places the Napoleonic wars in the 18th century - and, as usual, despite thanking her friends and mother for reading the material, there are too many printing errors. (Others have commented that copy editors are no longer affordable for publishers.) The most irritating thing is the opening assertion that the question more interesting than why the war broke out is why the peace failed. This is a false dichotomy equivalent to saying, don't tell me why my car broke down but tell me instead what needs to be fixed. This nonsense was presumably cooked up to justify writing yet another WW1 book, but despite being the thesis of the whole work, is quickly forgotten as she writes what is in fact a gripping 'why the war started' book.
Also, how is it possible for a serious author to create such an absurd title, despite all those friends, and mum? Every war is a war that ends peace.