LOL! Of course the traditional ameriKan ways is that only the fizicly and mentally fittest were allowed into the great murder-suicide machine. Moloch demands only the best and brightest young men!
The less intelligent are, on average, naturally more likely to die in war. However, in the case of the War of Northern Aggression, a lot of the more intelligent people of the South died than did the intelligent people of the North. College professors and such fought and died for the South, whereas in the North, that class avoided battle, and often military service altogether.
Confederate General Wade Hampton -- later governor of South Carolina -- said that the War for Southern Independence was a noble struggle for liberty and self-determination that cost the South "her best blood and all her treasure."
You've brought up an issue I've never heard mentioned despite it being obviously very major. My thesis is that humanity's in such a sorry state because of these endless wars, maybe 100k years' worth. Let's put it this way -- would the quality of ameriKa's life and population be worse or better if.....
*650,000 prime youth weren't killed in the un-civil war? Every Southern male capable of shouldering a rifle was pressed into service.
*350,000 prime young WHITE lives weren't sacrificed to the diversity god fighting to liberate the poor pitiful kikes in WW2 -- permanently putting ameriKa's existence on a purely 'diversity' footing?
*the tradition hadn't continued with over 100,000 more lost in Viet an Korea?
I'm forcing meself not to go into the many and vast kinds of blowback these losses entail. It's a huge effort, but duty calls. They call me Professor Overkill ;)