Fighting in Holes: Trench warfare

This first half of the week we discussed combat used on the Western Front of WWI, trench warfare. Where both sides dig massive series of intertwining pits, sit in them and shoot at each other. Every time I hear it mentioned I have to think, why did this last so long? Surely one side would have designed some sort of projectile to shoot straight up and reign down on the enemy trench. Some would say that makes me a bad person, but in truth it would have saved many lives by shortening the war. Thousands would have lived instead of dying over a couple of feet.