Why did it cause stalemate?
The failure of the Schlieffen plan was due to many different factors. First of all General Moltke changed the plan from its original conception into an offensive that was based more on the "hinge" of the thrust foward and less on the "hammer" thus meaning that Moltke reinforced the troops closer to Alsalce Lorraine and weakened the thrust of troops that would travel through Belgium and sweep through France to take Paris. Also Germany changed the plan so it didn't invade Holland, because Germany wished to keep a good trading relationship with Holland during the war, this had the effect of creating a bottleneck which the troops had to cram through in order to reach mainland France. This consequently slowed down the German assault, and because the assault was planned to the minute, with Train times and the mobilization of forces, the schlieffen plan lost its direction and in effect the plan became obsolete, from there on in the Germans had to improvise. Also the Germans were not expecting the resistance that the Belgians gave them, the Germans had to fight 3 long battles with the Belgians and that also slowed them down considerably. Also The introduction of the BEF, and the participation of the British Force slowed the Germans down and began to break up their formation. This time was vital for the French to bring up their army and abandon Plan 17, thus resulting in the conflict on the River Marne. It is also important to note that the Russian forces mobilized much quicker than expected and Moltke subsequently halved his force inorder to send the bulk of the troops to fight the greater threat and reinforce the Eastern Front. The Battle of the Marne was a huge success for the French due to the tactics employed by both the French and English. The BEF basically cut a hole right down the middle of the German force and split it in two thus allowing the French to overpower the German force and send them into a retreat. One must also consider that movement of soldeirs was slow due to the fact that there was a hiatus in military tactics and technology at the start of the war, as cavalry was still considered the main wepaon and machine guns could easily prevent the use of cavalry, thus more importance was stressed on the individual soldeir, who often carried around a large pack of supplies and ammo that slowed him down. This in effect slowed the Germans down once more. Some say that WW1 was lost at the battle of the Marne, and from then on in it was inevitable that the Germans would lose the war due to the pressures that they would come under as their country was encircled and could easily become blockaded (Germany only had enough resources to provide them with a 6 month war). Basically Germans retreated, dug in, used machine guns to protect themselves and their trenches, thus the British and French also dug in for cover. There was a race to the sea, and tactics didn't change until relatively late in the war, with the help of new technology that alllowed them to do so.