There was nothing that could have prepared the American Expeditionary Force for the battlefields of Europe when they entered the Great War in 1917. Both the Allies and the Central powers were deeply entrenched, fighting from bunkers dug into the earth. The opposing trenches formed parallel lines that ran from Belgium in the north to the border of Switzerland in the south. This defensive strategy, combined with new weapons such as the machine gun and poison gas, brought about heavy casualties for both sides.

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