99 years ago, the western front in the First World War was still in its brief maneuver phase, before settling into four years of trench warfare.
I suspect that the further that war recedes in time, the more incomprehensible the whole thing is. Imperial Europe destroyed itself over the question of who got to exercise influence in Serbia and the rest of the Balkans. Old Europe was at the height of its global power and influence at the beginning of 1914. But then some minor bit of royalty in central Europe was killed by a fanatic and they all went to war.
Once the western front was in trench warfare, the combatants fed troops and matériel into the fight as though they were feeding a perpetual meatgrinder.
It all seems so insane a century later. And yet, have we learned all that much since then? We still go to war with grandiose plans and when those plans fail, as they have for us in three wars over the last fifty years, there is no plan of what to do next other than gut it out, feed troops and matériel into the war in the hope the other side blinks first. The big lesson of the Great War wasn't "avoid trench warfare", it was "don't go to war over small shit, you morons. And don't go to war thinking that it'll be a lovely short four week or six month war."
My great-grandfather was killed in action in WWI. I wonder what the world lost in his death and in all the other millions who died. In vain.
"Morons" is being charitable.