1. The Schlieffen Plan's failure: The German war strategy, which called for a swift victory over France by encircling Paris, was known as the Schlieffen Plan. However, the French and British troops resisted the German assault in the First Battle of the Marne (September 1914), causing the strategy to fail.
2. The Western Front Stalemate: After the Schlieffen Plan failed, the war turned into a war of attrition along the Western Front. With millions of soldiers dead and few territorial changes, the conflict became a stalemate.
3. The entry of the United States into the war: In 1917, the United States declared war on Germany due to a number of factors, including unrestricted submarine warfare, the Zimmermann Telegram, and growing public sentiment in favor of supporting the Allied cause. The United States' entry gave the Allies a crucial advantage in terms of manpower, supplies, and economic power.
4. The British naval blockade: The British Royal Navy imposed a strict blockade of Germany, which severely limited the country's ability to import food, raw materials, and other vital supplies. This contributed to severe shortages and hardships on the German home front.
5. The effectiveness of the Allied economic blockade: The Allies' successful economic blockade of Germany prevented the country from importing vital supplies, including food, fuel, and raw materials. This led to widespread shortages and economic hardship in Germany.
6. The mutiny in Kiel: In response to the harsh conditions and the hopelessness of the war, German sailors mutinied at the naval base in Kiel in late 1918. The mutiny spread to other parts of Germany and eventually led to the abdication of Kaiser Wilhelm II and the proclamation of the Weimar Republic.