Final answer:
The trenches were formed in a zigzag pattern for tactical reasons and to provide better protection for soldiers. The zigzag pattern restricted the enemy's line of fire and allowed for better communication and movement within the trenches.
Step-by-step explanation:
The trenches were formed in a zigzag pattern due to tactical reasons and the new technologies of war. The zigzag pattern made it difficult for enemy troops to shoot down the entire length of the trench, providing better protection for the soldiers inside. Additionally, the zigzag pattern allowed for better communication and movement within the trenches, as it prevented easy access and direct line of sight for enemy soldiers. The trenches were also dug deeper over time to provide better protection against artillery shells and grenades.