The Fatally Flawed Assumptions of the Schlieffen Plan

Alfred Graf von Schlieffen

Stephen Van Evera

The Schlieffen Plan was a disastrous scheme that only approached success because the French war plan was equally  foolish: had the French army stood on the defensive instead of lunging into  Alsace-Lorraine, it would have smashed the German army at the French frontier. Yet General Schlieffen's plan was a sensible response to the offense-dominant world imagined by many Germans. The plan was flawed because it grew from a fundamentally flawed image of warfare.

In retrospect, Germany should have retained the later war plan of the elder Moltke (Chief of Staff from 1857 to 1888), who would have conducted a limited offensive in the east against Russia while standing on the defensive in the west. However, several considerations pushed German planners instead toward Schlieffen's grandiose scheme, which envisioned a quick victory against Belgium and France, followed by an offensive against Russia.

First, German planners assumed that France would attack Germany if Germany fought Russia, leaving Germany no option for a one-front war. By tying down German troops in Poland, an eastern war would create a yawning window of opportunity for France to recover its lost territories, and a decisive German victory over Russia would threaten French security by leaving France to face Germany alone. For these reasons they believed that France would be both too tempted and too threatened to stand aside. Bernhardi, among others, pointed out "the standing danger that France will attack us on a favorable occasion, as soon as we find ourselves involved in complications elsewhere." The German declaration of war against France explained that France might suddenly attack from behind if Germany fought Russia; hence, "Germany cannot leave to France the choice of the moment" at which to attack.

Second, German planners assumed that "window" considerations required a German offensive against either France or Russia at the outset of any war against the Entente. German armies could mobilize faster than the combined Entente armies; hence, the ratio of forces would most favor Germany at the beginning of the war. Therefore, Germany would do best to force an early decision, which in turn required that it assume the offensive, since otherwise its enemies would play a waiting game. As one observer explained, Germany "has the speed and Russia has the numbers, and the safety of the German Empire forbade that Germany should allow Russia time to bring up masses of troops from all parts of her wide  dominions."'  

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Operation Adjustments to Schlieffen and French Plan XVII Prior to Battle of the Marne

Germans believed that the window created by these differential mobilization rates was big, in turn, because they believed that both Germany and its enemies could mount a decisive offensive against the other with a small margin of superiority. If Germany struck at the right time, it could win easily—Germans hoped for victory in several weeks, as noted above—while if it waited it was doomed by Entente numerical superiority, which German defenses would be too weak to resist.

Third, German planners believed that an offensive against France would net them more than an offensive against Russia, which explains the western bias of the Schlieffen Plan. France could be attacked more easily than Russia, because French forces and resources lay within closer reach of German power; hence, as Moltke wrote before the war, "A speedy decision may be hoped for [against France], while an offensive against Russia would be an interminable affair."'  Moreover, France was the more dangerous opponent not to attack, because it could take the offensive against Germany more quickly than Russia, and could threaten more important German territories if Germany left its frontier unguarded. Thus Moltke explained that they struck westward because "Germany could not afford to expose herself to the danger of attack by strong French forces in the direction of the Lower Rhine," and Wegerer wrote later that the German strike was compelled by the need to protect the German industrial region from French attack.  In German eyes these considerations made it too dangerous to stand on the defensive in the West in hopes that war with France could be avoided.  

Finally, German planners believed that Britain would not have time to bring decisive power to bear on the continent before the German army overran France. Accordingly, they discounted the British opposition which their attack on France and Belgium would elicit: Schlieffen declared that if the British army landed, it would be "securely billeted" at Antwerp or "arrested" by the German armies,  while Moltke said he hoped that it would land so that the German army "could take care of it." In accordance with their "bandwagon" worldview, German leaders also hoped that German power might cow Britain into neutrality; or that Britain might hesitate before entering the war, and then might quit in discouragement once the French were beaten. Schlieffen expected that, "If the battle [in France] goes in favor of the Germans, the English are likely to abandon their enterprise as hopeless," which led them to further discount the extra political costs of attacking westward.

Given these four assumptions, an attack westward, even one through Belgium which provoked British intervention, was the most sensible thing for Germany to do. Each assumption, in turn, was a manifestation of the belief that the offense was strong. Thus while the Schlieffen Plan has been widely criticized for its political and military naivete, it would have been a prudent plan had Germans actually lived in the offense-dominant world they imagined. Under these circumstances quick mobilization would have in fact given them a chance to win a decisive victory during their window of opportunity, and if they had failed to exploit this window by attacking, they would eventually have lost; the risk of standing on the defense in the West in hopes that France would not fight would have been too great; and  he invasion of France and Belgium would have been worth the price, because British power probably could not have affected the outcome of the war.

Thus the belief in the power of "the offense was the linchpin which held Schlieffen's logic together, and the main criticisms which can be leveled at the German war plan flow from the falsehood of this belief. German interests would have been better served by a limited, flexible, east-only plan which conformed to the defensive realities of 1914. Moreover, had Germany adopted such a plan, the First World War might well have been confined to Eastern Europe, never becoming a world war. 

Source: Excerpted Selection from "The Cult of the Offensive and the Origins of the First World War,"  International Security, Summer 1984.  The full article can be downloaded.