Final answer:
The Schlieffen Plan failed due to underestimating Belgian resistance, unexpected British involvement, the rapid Russian mobilization, and logistical challenges, leading to a protracted and devastating trench warfare.
Step-by-step explanation:
The failure of the Schlieffen Plan can be attributed to several major factors, not precisely the options provided in the multiple-choice question. Some of the key reasons for the plan's failure include:
- Underestimating Belgian Resistance: The German army assumed they would easily pass through Belgium, but the Belgians fought back fiercely, delaying their advance.
- British Expeditionary Force involvement: Germany did not anticipate Britain's swift action to support France, thus contributing to the halting of the German advance.
- Rapid Russian Mobilization: Contrary to German expectations, Russia mobilized its troops much faster, forcing Germany to redirect troops to the Eastern Front.
- Logistical Challenges: The supply lines for the advancing German army became stretched and overburdened, leading to difficulties in maintaining the momentum of the assault.
These strategic miscalculations and logistical challenges led to a prolonged trench warfare situation, causing high casualties and ultimately the plan's failure.