What is one example of trench warfare ?

Trench warfare is a fighting style that was created during WWI to combat the new invention of machine guns which could mow down hundreds to thousands of men easily within seconds. By creating deep trenches, they were able to not be hit by the bullets that were above while still attacking. Enemies often used trenches themselves to protect themselves from the other sides machine guns.

AN ARMY DIGS A LON HOLE IN THE GROUND TO PROTECT TERRITORY.      (APEX)

Explanation:

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