The Doctrine of the British Army is a comprehensive study of British military thought between 1900 and 1918. The work seeks to explain how Field Service Regulations defined appropriate tactics, for every Western Front battle, under French and under Haig; and how it dictated the evolution of fighting units, and support formations, throughout the war. Between 1909 and 1914, the British Army transformed into a modern professional army, fit to compete in a continental war, by establishing the flexible doctrine, within a rigid framework, which would guide it to victory in 1918. This doctrine and the men who established it have long been overlooked. Essential reading for students and researchers, The Doctrine of the British Army restores Field Service Regulations to their rightful place at the centre of the story of the British Army. Then, as now, non-adherence led to failure, compliance to success in battle, in logistics and in the administration of war.