about Schlieffen's plan.
As stated earlier on the material conditions weren't met for it to be fully implemented, but do not forget the moral of the french troops at that time.
I have read that the germans would have entered Paris unopposed with their 2nd army had they gone according to the plan. Put this is simply not true.
We have a bias due to WWII, when Paris fell like a fruit in german hands, being declared open city by the french government.
But in 1914 the situation was very different, the french had been preparing for the war, at least mentally, since the 1870 crushing blow. French were litteraly ready to fight to the death ( actually so they did ). The government had left Paris for Bordeaux and Paris defence was under the command of Marshall Gallieni, a colonial hero, kinda Kitchener for the British. All the forts around Paris had been reequipped an d the city was ready for house by house fight
I know some of you might think this is an overstatement, but it isn't. Bear in mind that all the war on the western front was waged on the french soil ( ok some belgian as well ).
The key point of the failling of the modified Schlieffen pla was french retreat. After having counterattacked in Belgium and suffered horrendous losses at Charleroi and Namur, the French understood their mistake and retreated ( something they were not able to do in 1940 ). Actually even if tactically they had it all wrong in 1914 with their Napoleonical all out infantry offensive doctrine, the 1914 retreat is a masterpiece of strategical adaptation.
Indeed , by mid august th efrench realised that they were being outflanked by the germans on their left, so they needed to stop their fruitless attacking in Alsace and send troops there. But here the french railroad is a key factor. France is a very centralised country unlike germany and all the railroad web was built in a star/spider web shape, which means all railroads led to Paris, but they were no railroads going from the east to the north along the front.
So the french were unable to send troops ther fast enough. So they took the only possible decision at that time : retreat to have the front be a horizontal line going From Paris to the east. during the retreat they mustered troops coming from the east around their only railroad hub ( Paris ), forming the 6th army under Maunoury's command and waited for the German line to be overstretched to counter attack.
Schlieffen's goal was to encircle the french army by outflanking it. This plan had already failed whit the French army retreating in proper order. By this point the all out offensive they were carriyng was doomed to fail because of overstretched supply lines ( German forces in the west in 1914 numbered 1.8 million soldiers ).
Von kluck's turn to the east was a minor event that the french chose to exploit to counterattack. But had he not done it, he was going to face a newly mustered force anyway, just north from Paris.
The Germans retreated on the Aisne were they had prepared their new defensive line, not because they were beaten, but because they were running short on ammunition and supplies. The battle Of the Marne is actually a draw, after a 6 days fight the two armies were holding their ground, but instead of risking the loss of its westerner army ( Von kluk's first ) and maybe the second one too, which was also suffering from lack of ammunition at that time, he chose to retreat to buy some time.
this isn't a mistake, Moltke was a sound general, not a fanatic and he was not ready to sacrifice Von Kluck's army in a futile attempt to reach or encircle Paris. Although we cannot compare the battle of La Marne and Stalingrad, because they differ to almost every point, all Moltke did was avoiding what happened to Von Paulus army bogged down and unsupplied.
You must understand that for the german military doctrine, army destruction was the goal, and in the case of their armies the ultimate catastrophy to be avoided. They were still thinking in terms of decisive battle at time. whether it took place near Paris or near Berlin did not matter that much, if the German army had lost Von Kluck's, they risked not being able to adapt quickly enough to the new situation ( Being 400 kilometers deep in ennemy territory, in a time when soldiers walked all the way long, at least for the fighting units ).
I am not saying that in the battle of La Marne Von Kluck's arlmy was on the brink of destruction, but Moltke could simply not afford the risk, and as the momentum was lost, the moral as well, their was nothing else to do but to fall back on their defense line, which was only 70 Kms to the north ( he did not retreat until Germany and kept most of the gains made ).
Schlieffen's plan was too ambitious, and as the germans were not able to move their troops and most of all supplies fast enough, they needed a huge French mistake to be committed, such as the one they did in 1940 by running into Belgium. But as the french understood the extent of the risk and retreated, Schlieffen's plan was doomed by mid-august.
Woo... I am exhausted, my brain hurts so I'll adress the end of the war in an other post.