How did the allies stop the Germans from executing the schlieffen plan?

Answer 1

The Germans' Schlieffen Plan failed for several reasons. First, Russia mobilized more quickly then expected. After a few small Russian victories, German generals hastily shifted some troops to the east, weakening their forces in the west. Then, in September 1914, Bristish and French troops pushed back the German drive along the Marne River.
They didn't really. The Germans stopped themselves. To begin with the plan was ambitious, involving seven field armies in a line, pivoting like a giant fence gate closing through northern France. This did not impose heavy burdens on the soldiers nearest the pivot point, but for those at the end of the line, whose right sleeve was supposed to be brushing the sea, it involved hundreds of miles of marching, and occasionally fighting. By the end of a month these troops at the end of the line were staggering with exhaustion. The German high command attempted to exercise control of this moving mass of millions from far behind the lines, with very primitive communications, what modern methods of radio and telephone which were in use being very crude and unfamiliar to generals born in the middle of the nineteenth century.

One thing the Allies did do that upset the German plan was France begging its ally, Russia, in the most shrill and hysterical terms possible to do something in the east to cause the Germans to weaken their attack on France. This begging bore fruit, as the Russians, long before their mobilization was complete, did lurch into motion and head into eastern Prussia, faced by the eighth and last German field army. This early movement was not contemplated by the Schlieffen Plan and caused some consternation in Berlin. Orders went forth for the removal of three entire army corps - the equivalent of one to one and a half field armies - from the line in France and for these troops to be sent to the eastern front. These troops were on trains in transit when the early-moving Russians were met and defeated by the German troops already present on the eastern front, and so took no part in that action. The result was that these three army corps were no longer in the line in France, which had to be stretched to cover their absence, and also made no contribution in the east. The Russians never recovered really from this premature offensive into East Prussia.

The Germans themselves shortened the line of their attack, to the point where their offensive would sweep to the east of Paris, instead of enveloping and capturing Paris by passing to the west of the city. This was a tacit abandonment of the Plan, and an abandonment of the main purpose with which the plan had been originated - to defeat France swiftly, which the capture of Paris would have accomplished. Now the Germans no longer even intended to try for that goal in the initial push.