Why did the germans need to defeat france as quickly as possible in 19142

The Germans needed to defeat France as quickly as possible in 1914 so that they can turn their attention to Russia.

Remember, during WWI, the Germans were fighting a two-front war, and they believed that France and Britain was the weaker side (as Russia had a larger population). The Central Side set their goal on Paris, with hopes that, after taking Paris, the West side would crumble, and then they can divert all their resources to fighting Russia. However, this plan failed, leading to the slow defeat of the Central Power.

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supplies had to travel a long distance across water on ships that were often attacked, so they did not reach europe