Could the Schlieffen Plan ever have worked?

The short answer

• The two-front arithmetic. The Franco-Russian alliance of 1894 joined two powers whose combined strength exceeded Germany's. Schlieffen's proposed answer depended on their different mobilization speeds: defeat France during Russia's slower assembly, then turn east. The route through Belgium was chosen for speed, at the risk of British intervention. The western campaign had to be quick for the sequence to work; that necessity did not prove it could be made quick enough.
• A plan diluted, or a plan impossible?. Moltke the Younger weakened the right wing compared with Schlieffen's earlier sketch and allowed the Lorraine armies to counterattack rather than draw the French west. Traditionalists blame these changes. Historians who stress logistics question whether the original sweep was feasible either: marching men and horses needed supplies beyond the railheads, and cavalry faced rifles. The exhaustion and shortages of the actual right wing at the Marne give that objection weight, while leaving room to examine command decisions.
• Plan XVII and the cult of the offensive. France's Plan XVII also relied on attack. Its armies advanced into Lorraine under a doctrine that placed great faith in morale, but German firepower helped defeat the opening attacks within about ten days at terrible cost. Joffre subsequently used railways to move forces against the German flank. Both opening plans failed, and French forces were able to recover closer to their depots.
• Russia moves early — for its ally. Russia entered East Prussia in roughly two weeks, much sooner than the six German planners had expected, and before its army was fully ready. Part of its purpose was to help France. The resulting loss of Samsonov's army at Tannenberg was a severe price. Two German corps sent east were absent from the Marne; that absence alone does not explain the outcome there, but it shows how an ally can force an opponent to divide resources.

What it changed

The race to the sea — and the wall. After the Marne both sides tried to turn the other's northern flank, extending the fighting toward the sea. A fortified front came to run from the Swiss frontier toward the Channel. At First Ypres in Flanders, the old British regular army suffered grievous losses resisting a German offensive. Chapter 5 examines the trench system that followed.

Tannenberg makes a duumvirate. Hindenburg and Ludendorff emerged from Tannenberg as celebrated figures. By 1916 their authority had grown until they effectively directed the German war effort, pushing the Kaiser and chancellor into the background. Battlefield prestige had become political power.

Atrocity and the war of cultures. The killings at Louvain and Dinant supplied the Entente with evidence for its portrayal of a war against “the Hun.” Propaganda also exaggerated and embellished real crimes. Memories of those exaggerations later contributed to skepticism about atrocity reports in the next world war.

The shell famine. Armies consumed ammunition faster than prewar plans had allowed. Shell shortages helped drive governments to organize industrial production, bring scarce materials under control and employ women in munitions work. The crisis contributed to political upheaval in Britain and France. Industrial supply became central to sustaining and deciding the war.