IN August 1914 British strategic policy rested on four pillars. Britain would act as paymaster to the Entente. At sea the Royal Navy was expected to keep open the maritime lines of communication upon which Britain and its allies depended. On land the French and Russian armies would fight to contain the armies of the Central Powers with only minimal direct British assistance. Kitchener predicted that a moment would be reached in early 1917 when the land forces of all of the continental belligerents would be exhausted. Britain's New Armies could then intervene decisively in the land war, inflict a final defeat on the Central Powers, and enable the British government to dictate the peace settlement.
In September 1916 Lloyd George had promised to deliver the knock-out blow against Germany, and his only mandate to govern rested on the fact that a majority of MPs believed he was more likely than Asquith to do so. In December 1916 Lloyd George did not plan to deviate from Kitchener's strategy. But between December 1916 and May 1917, at the very moment when the British thought they should have been on the point of victory, the pillars of Kitchener's strategy crumbled. The exhaustion of Britain's financial resources in New York threatened the government's ability to act as paymaster to the Entente. The declaration of unrestricted U-boat warfare threatened the Royal Navy's ability to control the world's oceans. The Russian Revolution, coupled with the failure of the Nivelle offensive and the mutinies in the French army, cast doubt on how much longer Britain's major continental allies would be able to contain the armies of the Central Powers.
The War Cabinet was not compelled to adopt the expensive attritional policy it did pursue in the summer and autumn of 1917. They could, like Pétain, have opted to wait for the arrival of the Americans in 1918 before attempting to knock out Germany. They did not do so for a variety of reasons. To some extent the government was the prisoner of its own generals. Lloyd George inherited a group of senior military advisers who were intent on waging a war