[pest]

I would say WWI. Huddle in a cold wet trench, get the order to charge watch everyone get mowed down by machine gun and tangled in barbed wire or gassed. No relief because the enemy isnt leaving their trench, no medics. The next day the enemy does the same thing. Over the course of a year, the line moves maybe 300 yards, no real winner to the war. Civil war is right up there too.