Wikipedia gives the German death rate as about 4% of the population, giving 8% of men. I suppose one major difference is that in a tribal conflict perhaps everyone fought (because the conflict might be over in one short clash), whereas in more modern wars many work to sustain the war effort, and others are too old to fight, given longer lifespans.

This is very low compared to tribes:

https://en.wikipedia.org/wiki/War_Before_Civilization