Operation Alberich, the withdrawal of Imperial German forces to the Hindenburg Line in early 1917. The Battle of the Somme, although gruelling for the British and French forces involved, had managed to push German forces back almost 10 kilometres and had resulted in the development of two large salients (bulges) in the British line held by German forces. Increasing pressure by the British in the new year resulted in the decision to withdraw German forces from the salients, shortening the German line and reducing the manpower requirement for the occupation of the German front. The withdrawing forces would retire to a new defensive line constructed to the east of the Somme called the Siegfried Line (more commonly known as the Hindenburg Line amongst the Allies).

In preparation for the withdrawal, the German military initiated a scorched earth program, destroying any infrastructure that could have been valuable to the advancing Allies, roads, railways, bridges, wells, villages, trees, anything. Entire populations were forcibly moved eastward as well. As the German forces began their withdrawal on 9 February, 1917. As they withdrew, the left booby traps, usually artillery shells connected to pressure plates, buried under roads to be detonated by trucks and heavy wagons. Buildings were also booby trapped. German forces fought a rearguard action throughout the withdrawal, often attempting and often succeeding to convince the British that a German attack was imminent. This was remarkably effective and the British and French largely failed to detect the withdrawal of German forces and the first many British knew of the withdrawal was when patrols discovered that German positions were empty.