Forgive me for such a basic question, but aspects of trench warfare made to the war so horrible for people involved? My great grandfather said the happiest day of his life was when he got shot in the leg and was allowed to leave the trenches. I Know the conditions were bad and sickness was rampant, but still- What Made it so bad that a man would rather take a bullet than stay?
"The conditions were bad" is really the understatement of the century. It's a common anecdote that the combat was not the horrific part of the war -- at least you were doing something then. At least you were being active. It would start and have a clear, achievable end. It was the rest of the war that was the horrible part; the sitting in the trenches for days and weeks and months on end.
I really want you to close your eyes (well, metaphorically, you have to read!) and try to put yourself in your great grandfathers shoes. You would never get a full nights sleep for basically the duration of the war. Even officers who are criticized for being "separated" from the front would have to sneak in 15-45 minute naps throughout the day just to stay functional. You were constantly doing nothing but were still at such risk that you couldn't just lounge around and relax.
Your entire life would basically be one of fear. Depending where you were on the front you would be at risk of various threats of enemy snipers and artillery 24/7. Literally all day and all night you would be hearing sniper rounds pop off in your direction or an artillery round blow up somewhat nearby. I'd like to cite a journal entry from one Charles Edmonds to really emphasize this:
I never could stand shell--fire. I got into a thoroughly neurotic state during the day. Enduring a bombardment is the opportunity for that kind of nervous disease which made Dr. Johnson touch every post as he walked along Fleet Street. You think of absurd omens and fetishes to ward off the shell you hear coming. . .
So all the day you listened, calculated, hoped or despaired, making imaginary bargains with fate, laying odds with yourself on the chances of these various horrors. One particular gun would seem to be firing more directly on you than the others. You would wait for its turn so intently as to forget other perhaps more real dangers. At last it comes. You hold frenziedly on to the conversation; you talk a little too fast; your nerves grow tense, and while you continue to look and talk like a man, your involuntary muscles get a little out of hand. Are you knees quivering a little? Are you blinking? Is your face contorted with fear?
You wonder and cannot know. Force yourself to do something, say something, think or something, or you will lose control. Get yourself in hand with some voluntary action. Drum out a tune with your finger-tips upon your knee. Don't hurry - keep time - get it finished and you will be safe this once. Here superstition and neurasthenia step in. Like the child who will not walk on the lines in the pavement and finds real safety in putting each foot on a square stone you feel your ritual protects you. As the roar of an approaching shell rises nearer and louder you listen in inward frenzy to the shell, in outward calm to the conversation. Steady with those nervous drum-taps on your knee; don't break time or the charm is broken and the augury vain. The shell roars near. What was Thorburn saying
"Oh yes!"[sic], the rations come up at nine o'clock, enough for twice our numbers."
The "twist" at the end in case it blew over your head (it did for me my first pass through this passage at least :P) is that this wasn't some concentrated enemy offensive coming or a major effort by the enemy. It was just normal day to day artillery rounds coming toward him. The constant anxiety he would feel of being perpetually bombed and knowing that any second one stray round, one gust of wind, one little correction by some German a mile or two away could mean he's dead before he knows it. Now imagine living in that for months, years even. To make things even worse, which I hinted at earlier, is that the worse part was he couldn't do anything about it. It was the helpless of it all. He's being bombed and sniped at constantly and there's not a damn thing he or anyone else could do about it except curl up, get in a quiet spot, and wait for it to blow over. How powerless and even emasculating that must have been.
However it was those natural killers that you offhandedly mentioned that were the real killers of the war. Imagine having dozens of rats just living around you constantly. Some absolutely massive for our standards, some even eating the remains of the dead. Breeding, defecating, chirping rats. All day. The smell of bodies who were dead was constant. You would try to bury or cycle out as much of the dead as you can but when doing trench repairs you would likely smash into the decomposed skull of a man buried there for a few weeks/months. Yeah, his brain juice is now all over you. You aren't going to be able to wash it out for a while.
Mud and water would be constant. The Germans had the luxury of building their trenches where they wanted since they were the ones retreating and thus took the higher grounds. This left the Entente with the lower grounds -- with all the water and runoff going right into their trenches. So imagine all of those conditions above but with knee to waist high water everywhere. Not clear Hawaiian water but dirty, grungy, muddy, bloody, trash filled water. A lot of your life would just be trying to clear the damn water out.
Oh you would be cycled out from the front trench after a while. Depending where you were and what nation you were a part of you may be cycled "horizontally" across the entire front to more quiet sectors or may just be cycled back "vertically" toward the 'safer' areas of the trench. But those conditions would still apply. Instead of sitting at the front being picked at by snipers all day, covering worker parties, dealing with enemy raids, anxiously waiting the next enemy offensive, and repairing defensive works you would spend your nights delivering supplies (by hand of course, for thousands of people!) in the dead of night with snipers and machine guns popping off at you in thoroughly unfamiliar trench systems in that grungy, muddy water. Or you'd be put into a worker party that would be at the mercy of the enemy in no mans land fixing barbed wire. Eventually you would be given some legitimate rest at last but it would still be with the caveat of aforementioned constant artillery still being in range of you and constantly being on call to reinforce the main trench in event of an enemy offensive. Then right back to the front trench with you after maybe a few days of "rest".
Yeah, your great grandfather was not exaggerating when he said getting shot in the leg was the best day in his life. I'd have something a lot worse than getting shot in a leg done to me if it meant getting out of these conditions.
"Life and Death in the Trenches in the Trenches of the First World War", Andy Simpson
It was then first war when industrial war making capacity was applied to warfare. Mass made guns and bombs. Bigger weapons bigger engines, bigger platforms, all from the industrial age.