The broad outlines of the German war plan are usually attributed to Generaloberst Alfred von Schlieffen, chief of the German General Staff during 1891–1906. Schlieffen's offensive scheme was probably doomed in any case, but his successor, Generaloberst Helmuth von Moltke ("the Younger") made two modifications that proved fatal. Schlieffen had an overwhelming concentration on the right wing of German forces that would invade first Belgium and then France. These German armies were to secure the Channel ports, then sweep around Paris and drive French forces back against German Lorraine.
With French plans to invade Alsace and Lorraine in the event of war an open secret, Moltke assigned new army units that came on line in the years before the war to that sector, the German left wing. This meant that when war came, the weight of German forces would not be 59 divisions for the right wing north of Metz and 9 for the left wing, but rather 55 divisions on the right and 23 on the left. This adjustment was sufficient to repel the French forces invading Lorraine in August 1914, but the French units could then be redeployed against the main German armies to the north.
Moltke's second mistake was to misread the threat posed by Russia, which was faster to mount an offensive than anticipated. While the campaign against France was in progress, Moltke detached five divisions (some 80,000 men) from the right wing and sent them east. These troops were in transit at the time of the Battle of Tannenberg.
The heavily defended French frontier with Lorraine posed a formidable obstacle for an attacker, and the quickest way for the Germans to get at France was through neutral Belgium. The Belgian government rejected German demands for transit across its territory, forcing Germany to subdue that little country by force of arms, an act that brought previously neutral Great Britain into the war. Subduing Belgium upset the German timetable, but two weeks later they launched their invasion of France.
The British government, meanwhile, dispatched five divisions, virtually all of its regular army, to France. The small British Expeditionary Force (BEF), commanded by Field Marshal Sir John French, bought valuable time for the Western Allies to mobilize their resources, but everywhere the Allies were driven back. While to the north French Army units retreated in good order, French general Joseph J. C. Joffre saw his offensive into Lorraine repulsed by two German armies. He then put together a new army, the Sixth, commanded by General Michel Maunoury, to guard the capital while he regrouped his remaining forces. Although the Germans seemed to be enjoying great success in their advance, they were exhausted from the 300-mile march, and the French could rely on their excellent railroad net to bring up men and supplies.
By September 4 five German armies pressed along a line that sagged below the Marne River east and northeast of the French capital of Paris. These forces were, however, thinned by men left behind in Belgium or siphoned off to the Eastern Front, and along the Marne the Allies actually enjoyed a slight numerical advantage.
German First Army commander Generaloberst Alexander von Kluck, meanwhile, had taken a momentous decision. Believing his forces too weak to swing west and south of Paris as provided in the original plan, he ordered his army to swing east of the French capital to roll up the flank of the retreating French Fifth Army. The speed of his advance moved him ahead of Generaloberst Karl von Bulow's Second Army and exposed Kluck's right flank to the French Sixth Army and the Paris garrison.
Aerial reconnaissance identified the exposed German flank. Military governor of Paris General Joseph Gallieni, who had charge of defense of the capital, won approval from Joffre for an attack by Sixth Army, then under his control, north of the Marne. Joffre personally went to French's headquarters and there secured British support. Kluck, believing that the French and British were still in retreat and as yet unaware of the French Sixth Army's presence, continued to press his advance and disregarded an order from Moltke to protect Bulow's right flank that he knew would halt his advance for two days.
On the afternoon of September 5, Sixth Army's advance guard clashed with part of Kluck's First Army on the Ourcq River north of Meaux. The resulting contest was one of history's most decisive battles. Ranging from Belfort to north of Paris, the engagement involved more than 2 million men on the two sides. That night Joffre ordered all the Allied left-wing armies to turn and launch full-scale attacks on the Germans. His order, read to the men at first light on September 6, is as follows:
Now, as the battle is joined on which the safety of the country depends, everyone must be reminded that this is no longer the time for looking back. Every effort must be made to attack and throw back the enemy. A unit which finds it impossible to advance must, regardless of cost, hold its ground and be killed on the spot rather than fall back. In the present circumstances, no failure will be tolerated.Kluck, with his army split facing south on the Marne River and west on the Ourcq, now became aware of his grave situation. He ordered the rest of his army north to the Ourcq and turned to deal with Sixth Army. In fighting during September 7–9, Kluck forced the French onto the defensive. With General Michel Maunoury's Sixth Army fighting desperately to hold, Gallieni commandeered some 600 Parisian taxi cabs to transport 6,000 men to the front. Although the actual impact of these reinforcements does not match the post-event mythology, it did symbolize the linkage between Paris and the battle only 30 miles away.
When Kluck maneuvered on September 7 to meet Maunoury's threat, a gap of some 30 miles opened between his army and that of Bulow. Into this gap moved 20,000 men of the BEF, along with elements of General Franchet d'Espèrey's French Fifth Army. The next day Moltke, at German headquarters in Luxembourg, sent a trusted staff officer, Lieutenant Colonel Richard Hentsch, to visit commanders in the field and assess the situation. He instructed Hentsch that, if he discovered that the BEF had crossed the Marne and was moving into the gap between First and Second Armies, he was to order Bulow back to the Aisne River. Hentsch had sweeping powers to make whatever adjustments seemed appropriate.
It is a compliment to the German staff system that so junior an officer could have such authority. On September 9, after Hentsch had reviewed the situation with a deeply pessimistic Bulow and other commanders, he concurred with Bulow's decision to order Second Army to withdraw to the Aisne. Kluck's position was thus untenable and he too had to withdraw to the Aisne. By September 9 the Germans had fallen back all along the front. The battle ended three days later.
German losses in the First Battle of the Marne are unknown, but the allies captured at least 15,000 prisoners and 36 guns. The British sustained 1,700 dead and the French around 80,000 killed. Probably about a quarter of those engaged—roughly 250,000 men on each side—were casualties.
The tragedy of the Marne, from the French point of view, was that Joffre was unable to exploit his victory. The Germans retreated in good order; French troops were always too few and too late. Nevertheless, what the French soon called the "Miracle of the Marne" upset the German plans and denied Germany the quick victory it needed to win the war. Spencer C. Tucker
Blond, Georges. The Marne. Trans. H. Eaton Hart. Harrisburg, PA: Stackpole Books, 1966; reprint London: Prion Books, 2002; David, Daniel. The 1914 Campaign. New York: Military Press, 1987; Strachan, Hew. The First World War. Vol. 1. To Arms. New York: Oxford University Press, 2001; Tuchman, Barbara. The Guns of August. New York: Macmillan, 1963.
Spencer C. Tucker