What are they?
Well trench warfare was a technique used during the war, where soldiers were protected in these man dug trenches and would hide from the enemy in there for more than 24 hours.
Protected the soldiers
Provided them with a view of what was coming
also provided for a better protection from fire arms
The smell of dead bodies from previous fallen soldiers seemed to be a big concern
many on the soldiers contracted diseases
WW1 Life in the Trenches (Short Documentary)