Hindenburg Line (1917-18), name given by the British to a defensive arc of fortifications along the line Lens-Noyon-Rheims, started by the Germans in winter 1916 and known to them as the Siegfried Line. Believing his army to have been ‘exhausted’ at Verdun and the Somme, Ludendorff mounted ALBERICH, a strategic withdrawal from the 20 mile (32 km) bulge (‘Ancre knee’) of Army Group Crown Prince Rupprecht between Arras and Soissons. Troop withdrawals began on 15 March. The land left behind was stripped of all war material, tools, and food, wells were poisoned, streets mined, creeks dammed, railway sleepers ripped up, and all combustible material burned. The Allies, in Ludendorff's words, were ‘to find a totally barren land, in which their manoeuvrability was to be critically impaired’.
ALBERICH was the war's greatest feat of engineering. More than half a million German workers and Russian POWs toiled for four months building the line; 1, 250 trains hauled materials to construct the steel-reinforced concrete forts and blockhouses. The Hindenburg Line consisted of an elastic defence in-depth: an initial large antitank ditch yielded to a series of at least five barbed-wire barriers; next came a line of defence anchored by forts and blockhouses bristling with machine guns; and the final major barrier boasted an intricate system of zigzag trenches designed to prevent enfilading fire. Two lines of artillery were sited in the rear zone—on reverse slopes wherever possible, and later in trenches and tunnels. In time, the 300 mile (482 km) ‘line’ was extended to consist of five major defensive positions (Flanders, Wotan, Siegfried, Hunding, Kriemhild, and Michel Lines). Ludendorff judged that the Hindenburg Line freed up ten divisions as well as 50 batteries of heavy artillery, and shortened the front by nearly 30 miles (48 km). But it still required enormous manpower and in 1918, after his final offensives had used up his reserves, he saw his impregnable lines breached by the resurgent Allies.
— Holger H. Herwig
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