When the Schlieffen plan failed the German army ordered to begin to fall back. But after the German army has been chased by the allies they decided to start using defensive plans. The Germans stopped at the river and start making trenches to prevent the allies' progress towards the Germany. The Germans dug in using trenches to stop allies.
Trenches have been a very powerful defensive structures and a direct attack would probably mean a defeat. The German army used cement and even provided their soldiers with electricity. …
