Somehow, I don't think this represents WWII or Korea very accurately.
Yeah, I’m pretty sure that was debunked. I still hear it often though.
I doubt this is true for the Civil War.
Just look at the numbers killed.
Overall his numbers may be right though, but not for the reasons he assumes.
Considering that 85% of any military force is recruited from cities, and few of them could shoot strait, that leaves 15% from the countryside to do all the accurate shooting, and thereby, killing.