Originally the Germans were suppose encircle Paris but failed to this.
The Belgian army resisted the army invasion and slowed down the advance. Also the right wing of the German army weakened when two corps were taken to follow the Belgian army to Antwerp.
The French 5th army advanced northwards with the B.E.F on their left. They made a great tactical decision of not moving into a trap between the German 1st and 3rd armies.
The B.E.F dug themselves in a region of pit-heads and slag heaps, this caused a problem for the Germans who could not trace this well-concealed move and were gunned down by some excellently well trained rifle men of the B.E.F who the Germans thought were using machine guns.
The German army lost another two corps when Moltke thought the allies were defeated, it also weaken his right wing in France when he transferred his forces to East Prussia.
The allies retreated and were unable to be traced. They also kept changing their tactics this made it unable for the Germans to handle. Joffre (French army general) led the French with a rock-like steadiness. He shifted troops from Lorraine and formed a new army (6th) to the north of Paris in positions to the west of Klucks (German army general) line of advance.
The German supply difficulties increased as their communications lengthened and the German right wing drew together as gaps opened up..
Joffre intended that a retreat should stop a counter offensive to be launched.
Kluck switched most of his troops from near Grand Morin river to a position facing his 6th army, but by doing this he created a 34km between his and Burlows (another German General) 2nd army, covered only by weak rearguards and calvalry. This gap presented an excellent opportunity for the B.E.F and the French 5th armies they turned and advanced in Joffre's counter-offensive. Sir John French thought the gap might be a trap. It was really a question of nerve.
From the Schieffen plan the long-term causes were Molkte changing the plan, the plan being too ambitious and unrealistic, and the conditions from 1904 to 1914 had changed.
The short-term causes are the Belgians resisting, Russian mobilisation, the B.E.F helping France, the French defence and the German exhaustion from walking every where.
I think the main reason the scheiffen plan failed was because of the advances in technology
To sum this up I would say that the failure of the Schieffen plan was because of low morale from Molkte, poor German communications, Moltke modifying the plan and making it unrealistic, and the alliance between Belgium, France, and Britain. The failure of the Schieffen plan was a main factor that led to the stalemate on the western front.
