This is the book am reading at the hour and it's the book of the month in my reading group, I reviewed section Three of this book yesterday and it was amazing.
The First World War and the second has a lot of precipitated History and backlog attached to it, this book opens your eyes to them all and make you understand the whole thing in a better perspective, each data and assertion is backed up by evidences : newspaper headlines of the time, diary, archives and the likes and it now left for you who to believe.
I'll enjoin you to read it too.