In the spring of 1918, Germany made one last bid for victory in WWI. With Russia out of the war and the US not yet a factor in the military equation, there was a window of opportunity to defeat France and Great Britain and bring the war to an end. The German high command knew that the military balance was shifting against them; in a few months the Allies would possess an overwhelming superiority in men and material. March 1918 represented a “now or never” moment.
The first attack (Operation Michael) was launched on 21 March against the British Fifth Army. It gained more ground than any attack since the opening battles of 1914. Relentless pressure and innovative tactics threatened to shatter the Allies's front and win the war for Germany.
The crisis came in early April. The Kaiser's troops were within 15 miles of the vital rail lines and communication centers on which everything depended. Haig understood that the position of the entire BEF hung by a slender thread. There could be no more retreats.
He issued as special Order of the Day on 11 April 1918.
Haig's order possessed strategic insight as well as military desperation:
There is no other course open to us but to fight it out. Every position must be held to the last man: there must be no retirement. With our backs to the wall and believing in the justice of our cause each one of us must fight on to the end. The safety of our homes and the freedom of mankind alike depend upon the conduct of each one of us at this critical moment.
The Germans failed to win the war in April. In so doing they expended their strategic reserve and set the stage for their final defeat in the fall of 1918.
Haig’s ‘Backs to the Wall’ order had hit upon the key to victory: standing firm. The German tactics would succeed only if the initial blow shattered the cohesion of the defenders so comprehensively that the stormtroopers had little to do but mop up what was left. By fighting stubbornly, the British bought time for reserves to arrive.
Gary Sheffield, Forgotten Victory