During the First World War in September, 1914, after the Battle of the Marne, the Germans had to back to the river Aisne. There they dug trenches to protect themselves from the advancing French and British troops.
Step-by-step explanation:
Since the Germans were the first to build trenches they had chosen the best places to build them on this not only gave them an upper hand but also compelled the British and French to live in the worst conditions.
Dugouts and funk holes were made by soldiers to protect them from enemy fire and weather. Front-line trenches were protected by barbed wires and machine-gun posts.
Communication trenches were dug at such an angle to those facing the enemy and were used to transport men, food supplies and equipment.