Allan Mallinson has written a new history of the origins - and the opening first few weeks fighting - of what would become known as 'the war to end all wars'. He explains the grand strategic shift that occurred in the century before the war, the British Army's regeneration after its drubbings in its fight against the Boer, it's almost calamitous experience of the first 20 days' fighting in Flanders, and the point at which the BEF took up the pick and the spade in the middle of September 1914.