The Hindenburg Line (, Siegfried Position) was a German defensive fortification built during the winter of 1916–1917 on the Western Front in France during the First World War. The line ran from Arras to Laffaux, near Soissons, on the Aisne. In 1916, the Battle of Verdun and the Battle of the Somme left the German western armies () exhausted and on the Eastern Front, the Brusilov offensive had inflicted huge losses on the Austro-Hungarian armies and forced the Germans to take over more of the front. The declaration of war by Romania had placed additional strain on the Imperial German Army and the war economy.
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 devastating the intervening ground, the Germans could delay an Anglo-French offensive. 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.
Greater output of explosives, ammunition and weapons by German industry against the Allied (battle of equipment) was attempted in the Hindenburg Programme of August 1916. Production did not sufficiently increase over the winter, with only 60 per cent of the programme expected to be fulfilled by the summer of 1917. The German (peace initiative) of December 1916 had been rejected by the Entente and the Auxiliary Service Law of December 1916, intended further to mobilise the civilian economy, had failed to supply the expected additional labour for war production.
The retirement to the Hindenburg Line (/ Manoeuvre) took place from February to March 1917. News of the demolitions and the deplorable condition of French civilians left by the Germans were serious blows to German prestige in neutral countries. Labour was transferred south in February 1917 to work on the from La Fère to Rethel and on the forward positions on the Aisne front, which the Germans knew were due to be attacked by the French. Divisions released by the retirement and other reinforcements increased the number of divisions on the Aisne front to early April. The Hindenburg Line was attacked several times in 1917, notably at St Quentin, Bullecourt, the Aisne and Cambrai and was broken in September 1918 during the Hundred Days Offensive.
Background
Battle of the Somme, 1916
In August 1916 the German armies on the Somme had been subjected to great strain; the IX Reserve Corps had been "shattered" in the defence of Pozières. Ten fresh divisions had been brought into the Somme front and an extra division had been put into the line opposite the British. Movement behind the German front was made difficult by constant Anglo-French artillery harassing-fire, which added to equipment shortages by delaying deliveries by rail and interrupting road maintenance. Destruction, capture, damage, wear and defective ammunition had caused guns and guns to be out of action by the end of August.
The artillery deficit was only slowly improved by the plan of General Max von Gallwitz to centralise the command of the remaining artillery for counter-battery fire and to use reinforcements of aircraft to increase the amount of observed artillery fire, which had little effect on Allied air superiority but did eventually increase the accuracy and efficiency of German bombardments. The 2nd Army had been starved of reinforcements in mid-August to replace exhausted divisions in the 1st Army and plans for a counter-stroke had been abandoned for lack of troops. The emergency in Russia caused by the Brusilov Offensive, the entry of Romania into the war and the French counter offensive at Verdun had already overstretched the German army.
General Erich von Falkenhayn the German Chief of the General Staff was dismissed on 29 August 1916 and replaced by Field Marshal Paul von Hindenburg, with First General Erich Ludendorff as his deputy. (Third OHL, the new supreme command) ordered an end to attacks at Verdun and the dispatch of troops from there to Romania and the Somme front. On 5 September, proposals for a new shorter defensive position to be built in France were requested from the commanders of the western armies, who met Hindenburg and Ludendorff at Cambrai on 8 September. The western front commanders were told that no reserves were available for offensive operations, except those planned for Romania. Georg Fuchs, one of the corps commanders, recommended that a defensive line be built from Arras to west of Laon, shortening the front by and releasing ten divisions which, with other troops, could be used for an offensive in Alsace or Lorraine. Ludendorff criticised the practice of holding ground regardless of its tactical value and advocated holding front-line positions with a minimum of troops and the recapture of lost positions by counter-attacks, a practice that had already been forced on the German armies on the Somme.
On 15 September Crown Prince Rupprecht, commander of the northern group of armies, was ordered to prepare a rear defensive line and on 23 September work on the new (Siegfried Position/Hindenburg Line) began. On 21 September, after the battle of Flers–Courcelette (15–22 September), Hindenburg ordered that the Somme front would have priority in the west for troops and supplies. By the end of the Battle of Morval (25–28 September) Rupprecht had no reserves left on the Somme. During September, the Germans sent another thirteen fresh divisions to the British sector and scraped up troops wherever they could be found. The German artillery fired of field artillery shells and of heavy ammunition, yet the début of the tank, the defeat at the Battle of Thiepval (26–28 September) and the number of casualties (September was the costliest month of the battle for the German armies) were severe blows to German morale. On 7 October, Rupprecht anticipated a British attack north of the Ancre River in mid-October, anxiety about the situation at Verdun also increased. On 19 October, the dispatch of reinforcements from Verdun to the Somme was suspended. Defeats inflicted south of the Somme by the French Tenth Army (10–21 October) led to the sacking of Bronsart von Schellendorf, the 2nd Army chief of staff.
German strategy for 1917
Hindenburg Programme
Hindenburg and Ludendorff demanded domestic changes to complement their new strategy. German workers were to be subjected to an Auxiliary Service Law () that from November 1916, subjected all Germans from {16 to 50 years old to compulsory service. The new programme was intended to create a trebling of artillery and machine-gun output and a doubling of munitions and trench mortar production. Expansion of the army and output of war materials caused increased competition for manpower between the army and industry. In early 1916, the German army had in recruit depots and another in March when the 1897 class of conscripts was called up. The army was so flush with men that plans were made to demobilise older classes and in the summer, Falkenhayn ordered the raising of another for an army of
The costly battles at Verdun and the Somme had been much more demanding on German divisions and they had to be relieved after only a few days in the front line, lasting about 14 days on the Somme. A larger number of divisions might reduce the strain on the and realise a surplus for offensives on other fronts. Hindenburg and Ludendorff ordered the creation of another 22 divisions, to reach 179 divisions by early 1917. The men for the divisions created by Falkenhayn had come from reducing square divisions with four infantry regiments to triangular divisions with three regiments, rather than a net increase in the number of men in the army. Troops for the extra divisions of the expansion ordered by Hindenburg and Ludendorff could be found by combing out rear-area units but most would have to be drawn from the pool of replacements, that had been depleted by the losses of 1916. Although new classes of conscripts would top up the pool, casualty replacement would become much more difficult once the pool had to maintain a larger number of divisions.
By calling up the 1898 class of recruits early in November 1916, the pool was increased to men in February 1917 but the larger army would become a wasting asset. Ernst von Wrisberg (de) Deputy Minister of the Prussian Ministry of War, responsible for raising new units, had grave doubts about the wisdom of this increase in the army but was over-ruled by Ludendorff. The German army had begun 1916 equally well-provided for in artillery and ammunition, massing field and heavy artillery shells for the beginning of the Battle of Verdun but four million rounds were fired in the first fortnight and the 5th Army needed about trains a day to continue the battle. The Battle of the Somme further reduced the German reserve of ammunition and when the infantry was forced out of the front position, the need for (defensive barrages) to compensate for the lack of obstacles, increased.
Before the war, Germany had imported nitrates for propellant manufacture and only the discovery before the war of the Haber process for the synthesis of nitrates from atmospheric nitrogen, enabled Germany to produce explosives while blockaded. Developing the process and building factories to exploit it took time. Under Falkenhayn, the procurement of ammunition and the weapons to fire it, had been based on the output of propellants, since the manufacture of ammunition without sufficient propellant fillings was as wasteful of resources as it was pointless; Hindenburg and Ludendorff wanted firepower to replace manpower and ignored the principle. To meet demand and to feed new weapons, Hindenburg and Ludendorff wanted a big increase in propellant output to a month. In July 1916, the output target had been raised from , that was expected to cover existing demand and the extra of output demanded by Hindenburg and Ludendorff could never match the doubling and trebling of artillery, machine-guns and trench mortars.
The industrial mobilisation needed to fulfil the Hindenburg Programme increased demand for skilled workers, (recalled from the army) or exempted from conscription. The number of increased from men, of whom deemed (kv, fit for front line service), at the end of 1916 to men in October 1917 and more than two million by November, being kv. The demands of the Hindenburg Programme exacerbated the manpower crisis and constraints on the availability of raw materials meant that targets were not met. The German army returned workers to the war economy and exempted from conscription, from 1917.
Steel production in February 1917 was short of expectations and explosives production was below the target, which added to the pressure on Ludendorff to retreat to the Hindenburg Line. Despite the shortfalls, by the summer of 1917, the artillery park had increased from guns and from guns, many being newer models of superior performance. Machine-gun output enabled each division to have and machine-guns and for the number of (MGA, machine-gun sharpshooter detachments) to be increased. The greater output was insufficient to equip the new divisions; existing divisions, which still had two artillery brigades with two regiments each, lost a regiment and the brigade headquarters, leaving three regiments. Against the new scales of equipment, British divisions in early 1917 had and machine-guns and the French and machine-guns.
Unrestricted U-boat warfare and strategic bombing