The Hindenburg Line, built behind the Noyon Salient, was to replace the old front line as a precaution against a resumption of the Battle of the Somme in 1917. By wasting the intervening ground, the Germans could delay a spring offensive in 1917. A shortened front could be held with fewer troops and with tactical dispersal, reverse-slope positions, defence in depth and camouflage, German infantry could be conserved. Unrestricted submarine warfare and strategic bombing would weaken the Anglo-French as the German armies in the west () recuperated. On 25 January 1917, the Germans had 133 divisions on the Western Front but this was insufficient to contemplate an offensive.