Only against Russia did the Central Powers actually prevail. On the Western Front, from 1914 down to the summer of 1918, the record was one of frustration. And one central factor helps to explain this, the balance of military materiel. From the summer of 1916 onwards when the British Army brought an enormous transatlantic supply line to bear on the European battlefield, it was only ever a matter of time before any local superiority established by the Central Powers was turned into its opposite.
