1. The Schlieffen Plan: This was the German military strategy for defeating France, which involved a rapid advance through Belgium and into France, bypassing the French defences and encircling the French army. The plan failed, however, as the French and British were able to halt the German advance at the Battle of the Marne in September 1914.
2. The Battle of Verdun: This was one of the bloodiest battles of the war, and resulted in a heavy defeat for the Germans. The French were able to defend the city of Verdun, and the German army suffered heavy casualties.
3. The Battle of the Somme: This was another major battle of the war, and again resulted in a heavy defeat for the Germans. The British and French launched a massive offensive, and the German army was unable to resist.
4. The United States: The United States entered the war in 1917, and its fresh troops and resources helped to tip the balance in favour of the Allies. The Americans were able to break through the German defences, and the German army was forced to retreat.
5. The Home Front: The German home front was also under strain, and the people were becoming increasingly tired of the war. There were food shortages, and the economy was in decline. This made it difficult for the German government to continue the war.
In summary, there were a number of factors that contributed to Germany's loss in World War 1, including the failure of the Schlieffen Plan, the heavy defeats at Verdun and the Somme, the entry of the United States into the war, and the strain on the German home front.