The Schlieffen Plan, devised a decade before the start of World War I, outlined a strategy for Germany to avoid fighting at its eastern and western fronts simultaneously. But what had been meticulously designed to deal a swift “right hook” attack on France and then advance on Russia, dragged on to become an ugly, brutal war of attrition.

“The Schlieffen Plan didn’t work because it was based on everything going right and it had no contingencies for the fog of war,” says Peter Fritzsche, professor of history at the University of Illinois.

The Schlieffen Plan got its name from its creator, Count Alfred von Schlieffen, who served as chief of the Imperial German General Staff from 1891 to 1906. Count Schlieffen drew up the operation between 1897 and 1905 after an alliance established between Russia and France in 1891 meant that Germany could face a two-front war.

Schlieffen’s strategy assumed that Russia, having recently lost the Russo-Japanese War, would take at least six weeks to mobilize its troops and attack Germany from the East. In that time, Germany would stage an attack on France by marching west through the neutral territory of the Netherlands and Belgium.

This route avoided the heavily fortified direct border with France. Then German forces would swoop south, delivering a hammer blow through Flanders, Belgium and onward into Paris, enveloping and crushing French forces in less than 45 days.

Once France was defeated, according to the plan, Germany could transport its soldiers east using its railroad network and deploy them against the Russian troops, which Schlieffen believed would require six weeks to mobilize and attack Germany’s eastern border.

Schlieffen’s plan was adopted by Helmuth von Moltke, chief of the German General Staff when war broke out in 1914. Moltke made some critical modifications to the plan, including reducing German forces making up the right hook attack into France and invading through Belgium, but not the Netherlands, during the initial offensive.

The problem, says Prof. Fritzsche, is the Schlieffen blueprint proved inflexible. First, Belgium refused Germany's free passage and fought the incoming German soldiers.

Moreover, the violation of Belgium’s neutral territory drew England into the war since they had promised to defend Belgium under the Treaty of London of 1839.

After facing fierce resistance in Belgium and with soldiers from the British Empire in the fight alongside France, Germany’s planned swift offensive was slowed.

Russia also proved to be more adept at mobilizing its army than German military leaders had expected. Russia managed to attack East Prussia within 10 days in August 1914 – not six weeks as was earlier assumed.

The Russian initial offensive was defeated, but their advances prompted Germany to send corps from France to East Prussia, bleeding Germany’s forces on the Western Front of essential fighting manpower.

The Schlieffen Plan’s strategy required that France be defeated swiftly – but this didn’t happen. That failure led to sustained trench warfare on the Western Front. In those grim battles of attrition, such as the Battle of the Somme and the Battle of Verdun, Allied forces ultimately outnumbered the Germans.

As Moltke told Kaiser Wilhelm II after exhausted German forces were defeated at the Battle of the Marne, “Sir, we have lost the war.”

Four years later, Moltke’s prognosis would prove correct.