This video is well worth watching. It shows the deaths caused by war over the years, concentrating on WW2.
It really blows your mind to look at those numbers, tens of millions of people just gone in such a short amount of time. I wonder how the world would be different if not for all those deaths, and I believe it said the average age of the dead soldiers was around 23, so much life left to live, learn, so much lost opportunity, all that sacrifice. WWII was truly a singularity in the history of warfare. I wonder how many people I actually know in my life a thousand, two thousand, more? Each of those little men representing a thousand people, I can’t even wrap my head around the enormity of it, I have no basis for comparison in my every day life. Stalin said it best: “the death of one is a tragedy, the death of a million is just a statistic”.
Given that they were mostly right about prime reproducing age, the world would probably be much more over-populated than it already is!