In the winter of 1915, the Supreme Army Command (OHL) under Erich von Falkenhayn began planning an offensive for the coming year. All strategically possible and promising front sections were discussed. The OHL came to the conclusion that Great Britain had to be driven out of the war, since its exposed maritime position and its industrial capability made it the engine of the Entente. Based on these considerations, Italy was discarded as an unimportant target for attack. Likewise Russia: although German and Austro-Hungarian forces had made major territorial gains in the July-September 1915 campaign against Russia, Falkenhayn was convinced that German forces were insufficient for a decisive advance because of the vast size of the Russian Tsarist Empire. Even the capture of St. Petersburg would be only symbolic in nature and would not bring a decision due to a retreat of the Russian army into the area. Ukraine would be a welcome fruit of such a strategy because of its agriculture, but it was likely to be plucked only with the unequivocal consent of Romania, since the latter's entry into the war alongside the Entente was to be prevented. Other theaters in the Middle East or Greece were designated as irrelevant. This left an attack on the Western Front as the only option. In the meantime, however, the British positions in Flanders had been built up to such an extent that Falkenhayn proposed the French front as the decisive theater of war.
He argued: "France [has] come close to the limit of what is still tolerable in her achievements - by the way, with admirable sacrifice. If it succeeds in making clear to its people that they have nothing more to hope for militarily, then the limit will be crossed, England will have her best sword knocked out of her hand." Falkenhayn hoped that the collapse of French resistance would be followed by the withdrawal of British forces.
He considered the strongholds of Belfort and Verdun as targets for attack. Due to the strategically rather insignificant location of Belfort near the German-French border and the possible flanking of the fortress of Metz, the Supreme Army Command decided in favor of the fortress of Verdun.
At first glance, Verdun's strategic position in the frontal belt promised a worthwhile target: after the border battles in September 1914, the German offensive had formed a wedge in the front at Saint-Mihiel, which hung as a constant threat in front of the French defenders. This allowed the German 5th Army under Crown Prince William of Prussia to attack from three sides, while the French High Command (GQG - Grand Quartier Général) was forced to withdraw troops from other important sections of the front and move them to the attacked section via the narrow corridor between Bar-le-Duc and Verdun. On the other hand, a look at the geography gives a completely different picture: the French fortifications had been dug into the slopes, forests and peaks of the Côtes Lorraines. The forts, fortified dugouts, walkways, concrete blockhouses and infantry works were almost impossible obstacles for the attacking soldiers to take; barbed wire, brush, undergrowth and the difference in altitude of up to 100 meters to overcome also hindered the attackers. One had to reckon with great losses.
To counter these conditions, the attack of the German units was to be prepared with a gunfire of previously unknown extent. The strategic plan was given the name "Chi 45" - the name for "court" according to the secret key in force at the time. At Christmas 1915, Kaiser Wilhelm II gave permission for the offensive to be carried out. The actual attack was to be led by the German 5th Army under Crown Prince Wilhelm of Prussia on the east bank of the Meuse. A large-scale attack on both sides of the river was ruled out by Falkenhayn. This apparently counter-intuitive decision, which failed to take into account the superior position of the Germans on both sides of the river, was sharply criticized by both Crown Prince Wilhelm and Konstantin Schmidt von Knobelsdorf, Chief of Staff of the 5th Army and the actual decision-maker. Nevertheless, no modifications were made to "Chi 45".
Falkenhayn's goals
While the capture of the city by German troops would have had a negative impact on French war morale, Verdun could not have been used as a launching point for a decisive attack on France. The distance to the French capital Paris is 262 kilometers, which would have been almost insurmountable in such a war of position.
In his memoirs on his time in the OHL, published after the war (1920), Falkenhayn claims that as early as 1915 he had spoken of a strategy of attrition, a tactic of "tear out and hold." The fact that Falkenhayn had not launched a concentrated attack on either bank of the Meuse River, which might have meant the rapid capture of Verdun, is often cited in support of this statement. One interpretation of this decision was that the OHL thereby wanted to avoid direct success, thus concentrating French troops in front of Verdun for defense. In this respect, therefore, Falkenhayn would actually have intended not the capture of Verdun but the involvement of the French army in a protracted battle of attrition that would eventually lead to the complete exhaustion of France in material and personnel. This plan, however, cannot be proved by any records except those written by Falkenhayn himself and much later, and is today regarded skeptically but not as impossible. In fact, Falkenhayn believed in a counterattack on the flank and wanted to hold back appropriate reserves so that he could not provide enough troops for a simultaneous attack on both banks of the Meuse. Falkenhayn by no means wanted to avoid a direct success.
It is more likely, and therefore a common reading, that Falkenhayn, as head of the army a rather hesitant strategist, did not pursue this strategy from the beginning, but only declared it to be a means to an end in the course of the battle; this mainly as a justification against the background of the unsuccessful advances and the high own losses. This interpretation is clearly supported by the orders given to the fighting troops, which were designed to gain ground: Falkenhayn ordered an offensive "in the area of the Meuse in the direction of Verdun," the crown prince declared to "quickly bring down the fortress of Verdun," and von Knobelsdorf had given the two attacking corps the task of "advancing as far as possible." The attacking 5th Army put these orders into action without tactically waiting, following the bleeding-out strategy, and without attacking exclusively for high foreign casualties. The primary objective of the attack was to conquer the high ground on the east bank of the Meuse River in order to bring its own artillery into a commanding position there.
The fortress of Verdun
→ Main article: Verdun Fixed Square
From the French point of view, defending Verdun was a patriotic duty, but one that completely contradicted the modern military view: a strategic retreat to the wooded ridges west of Verdun would have created a much easier defensive position, erased the bulge, and freed up troops. But the French military doctrine of 1910, vehemently advocated by Joffre, was the offensive à outrance (roughly, 'to the extreme'). Defensive tactics or strategy were never seriously considered. When some officers, including General Pétain and Colonel Driant, expressed misgivings about this doctrine, their stance was rejected as defeatist.
Driant, as commander of the important section in Caures Forest and commander of the 56th and 59th Battalions of Chasseurs à pied, had tried several times in vain to persuade the GQG to make significant improvements in the French trench system. On his own, Driant had his fighters fortify their position against the expected attack; nevertheless, Driant fell in the first assault on 22 February. Complementary to a sensible defense, the GQG and Joffre relied on the system of French defense by attack, the backbone of which was the thrust of the poilu, the common soldier whose cran, his courage, would give him the decisive advantage.
After the Franco-Prussian War of 1870/71, France proceeded to secure the border with the German Empire by building fortifications (barrière de fer) that were contemporary at the time, despite the conviction that victory could only be achieved by an infantry advance. To this end, several eastern French cities were surrounded with a ring of forts, including Verdun, located on the Meuse River. Verdun was seen primarily as a replacement for the lost Metz, whose old fortifications had been greatly expanded by the Empire. At the beginning of the war, there were over 40 fortifications in and around Verdun, including 20 forts and intermediate works (ouvrages) equipped with machine guns, armored observation and gun turrets, and casemates. Verdun was thus one of the best fortified sites. Another reason for the particularly strong development of the Verdun fortress was the short distance of 250 km to Paris, even for the means of transport of the time, as well as its location on a main road.
Already from September 22 to 25, 1914, there had been fighting in front of Verdun, which had ended the German advance in the Meuse region. Under the impression of the enormous destructive power of the German siege guns before Namur and before Liège, the importance of strong fortifications in an attack with heavy siege guns (for example 30.5-cm siege mortars) was seen differently than before.
Also, the siege of Maubeuge (it began on August 28, 1914 and officially ended on September 8, 1914 with the surrender of Maubeuge) - had shown Germans and French that fortresses were not impregnable but could be 'shot up'.
This, together with the fact that the warring parties concentrated on other sections of the front in the aftermath of the border battles, led to a lesser military importance of Verdun after a reassessment: the GQG under Joffre declared Verdun a quiet section. On August 5, 1915, the fortress of Verdun was even officially downgraded to the center of the Région fortifiée de Verdun - RFV ("Fortified Region of Verdun"). In the months that followed, 43 heavy and 11 light gun batteries were consequently withdrawn from the fortified ring and most of the forts' machine guns were transferred to field units. Only three divisions of the XX Corps were now stationed there:
- the 72nd Reserve Division from the Verdun region,
- the 51st Reserve Division from Lille and
- the 14th regular division from Besançon.
The 37th Division from Algeria was in reserve.