Why did the Schlieffea plan fail?

Question 1

Part 1 of S. Plan:

Answer 1

France/Western Front: Germany attacks France to be quick, but instead Trench war occurs and neither side advances, halting Germany and leading to a 2 front war

Question 2

Part 2 of S. Plan:

Answer 2

Russia/ Eastern Front: Germany assumed Russia would mobilize slowly and originally wanted to deal with them second.

Question 3

2 reasons for plan fail

Answer 3

1) Germany is surrounded by enemy countries 2) The alliance system/ Triple Entente