One of the great problems for any historian writing of 1914 and the slide into conflict is that everyone knows the causes of the first world war and those of us who don’t still imagine that we do. It is clear that no historian can simply ignore the causes and get straight down to the fighting, but with the best will in the world it is hard not to feel like some poor Easyjet passenger, stranded on a Gatwick runway and sadly watching the precious take-off slot slipping further into the distance while the cabin crew go though the familiar...