Firstly, the deficient plans of the both countries, Germany and Austria-Hungry, led to their defeat. Both countries had their own plans which were the Schlieffen Plan and the Plan R respectively. The former was to defeat France in six weeks by invading at high speed at Belgium, so that the German armies could turn to fight the Russians. However, Germany's invasion of France went wrong that Belgian army and British Expeditionary Force fought better- which slowed down the German troops- and the Russian army attacked Germany sooner than it expected. Hence, Germany fought over two countries at the same time which means it had to split its army. Furthermore, the long journey to France form Germany made the soldiers exhausted. This shows that the plan was badly made that it failed to know the capabilities of its own country and the enemy as well. Besides, the Plan R of Austria-Hungary also failed that it was defeated by Russia. The Plan R was to send huge forces across the border into Russia. At first, the Austrian armies were able to capture great areas of Russia, but within a week they turned and retreated over 200 kilometers. They even left heavy guns and ammunition behind them. Moreover, Austria was also being beaten in its attack on Serbia. (Why is this show Plan R was a bad one?????!!!!!!) The poor plans caused losses in the battlefield that both countries had a vast number of casualties.
Secondly, the British blockade which led to the lack of materials was a key factor in the defeat of Germany. As Great Britain had the largest army in the world, it was also effective in blockading the materials that were supplied to