In 1904 France and Britain signed the Entente Cordiale (friendly understanding). The objective of the alliance was to encourage co-operation against the perceived threat of Germany. Negotiations also began to add Russia to this alliance. As a result of these moves the German military began to fear the possibility of a combined attack from France, Britain and Russia.
Alfred von Schlieffen, German Army Chief of Staff, was given instructions to devise a strategy that would be able to counter a joint attack. In December, 1905, he began circulating what later became known as the Schlieffen Plan. Schlieffen argued that if war took place it was vital that France was speedily defeated. If this happened, Britain and Russia would be unwilling to carry on fighting. Schlieffen calculated that it would take Russia six weeks to organize its large army for an attack on Germany. Therefore, it was vitally important to force France to surrender before Russia was ready to use all its forces.
Schlieffen's plan involved using 90% of Germany's armed forces to attack France. Fearing the French forts on the border with Germany, Schlieffen suggested a scythe-like attack through Holland, Belgium and Luxembourg. The rest of the German Army would be sent to defensive positions in the east to stop the expected Russian advance.
When Helmuth von Moltke replaced Alfred von Schlieffen as German Army Chief of Staff in 1906, he modified the plan by proposing that Holland was not invaded. The main route would now be through the flat plains of Flanders. Moltke argued that Belgium's small army would be unable to stop German forces from quickly entering France. Moltke suggested that 34 divisions should invade Belgium whereas 8 divisions would be enough to stop Russia advancing in the east.
On 2nd August 1914, the Schlieffen Plan was put into operation when the German Army invaded Luxembourg and Belgium. However, the Germans were held up by the Belgian Army and were shocked by the Russian Army's advance into East Prussia. The Germans were also surprised by how quickly the British Expeditionary Force reached France and Belgium.
On 3rd September, Joseph Joffre, the Commander-in-Chief of the French forces, ordered his men to retreat to a line along the River Seine, south-east of Paris and over 60km south of the Marne. Sir John French, commander of the British Expeditionary Force agreed to join the French in attacking the German forces.
The French 6th Army attacked the German Ist Army at the Marne on the morning of 6th September. General Alexander von Kluck wheeled his entire force to meet the attack, opening a 50km gap between his own forces and the German 2nd Army led by General Karl von Bulow. The British forces and the French 5th Army now advanced into the gap that had been created splitting the two German armies.
For the next three days the German forces were unable to break through the Allied lines. At one stage the French 6th Army came close to defeat and were only saved by the use of Paris taxis to rush 6,000 reserve troops to the front line. On 9th September, General Helmuth von Moltke, the German Commander in Chief, ordered General Karl von Bulow and General Alexander von Kluck to retreat. The British and French forces were now able to cross the Marne.
The Schlieffen Plan had not succeeded. The German hopes of a swift and decisive victory had been frustrated. However, the German Army had not been beaten and its successful retreat and the building of trenches between the North Sea to the Swiss Frontier ended all hope of a short war.