Why do you think artillery became such a major part of trench warfare?

The trenches keep soldiers sheltered from small arms fire and artillery. - Trench warfare is a form of attrition warfare ... - Because attacking an entrenched enemy was so difficult, tunneling underneath enemy lines became on of the major efforts during the war.

Artillery was a game changer in trench warfare. The right equipment could easily destroy enemy trenches, and even take out opposing artillery as well.