“Lessons learned” in WWI: The German Army, Vimy Ridge and the Elastic Defence in Depth in 1917

In late 1916, the German 3rd Supreme Army Command (OHL) under General Hindenburg and General Ludendorff decided to go onto a strategic defensive on the main front in the west. With the help of the tactical lessons learned in the battle of materiel at the Somme, the OHL developed the principle of elastic defense in depth. It consisted of mounting a mobile and offensive defense that granted the forces limited room to withdraw and was primarily based on immediate counterstrokes being conducted by reserves. For this purpose, the bulk of the force would no longer be concentrated in the front line, but were to disperse in a several kilometer deep position area. This new doctrine, which was by no means uncontested among German commanders, faced the crucial test when the Anglo-Canadian attack on Vimy Ridge /Arras was launched on 9 April 1917. As a consequence of blatant leadership errors and a flawed implementation of the principles of elastic defense, the German defenders lost Vimy Ridge at the beginning of the battle. Nevertheless, the allied breakthrough attempt ended in early May 1917 in failure and with severe losses. This paper shows how the German side learned from the battles at Vimy/Arras and optimized its system of elastic defense for the forthcoming defensive operations in 1917