Artillery
Artillery played a crucial role in World War I. The artillery was a bunch of massive guns that would decimate anyone unlucky enough to be in the way. They had massive shells that would usually explode on contact, taking out large number of the enemy forces. The longest barreled artillery would be shot straight on to vaporize anyone in it's path and the shorter barreled ones called morters would be shot at a high angle and would rain down explosives from above to rip apart groups of enemies. Morters could also be fired from the safty of the trench. Artillery was a huge part of WWI and is probably the neatest weaponery in the war in my opinion.