Germany's invasion of France in August 1914 represented a threat to the great power status of both Britain and France. The countries had no history of cooperation, yet the entente they had created in 1904 proceeded by trial and error, via recriminations, to win a war of unprecedented scale and ferocity. Elizabeth Greenhalgh details the civil-military relations on each side, the political and military relations between the two powers, the maritime and industrial collaboration that were indispensable to an industrialized war effort and the Allied prosecution of war on the western front.