Answer:
Due to trench warfare being the trend during the war, proper military and guerrilla tactics to end wars faster weren't being used. So nobody would advance unless an assault to the enemy trench was made and assault weren't fun because you would lose large quantities of men. Since trenches were easy to defend against ground troops a large quantity of men were required to have a chance at gaining the trench. So in the end little advancements were made.
Explanation:
