I think the trouble is that you're emotionally wedded to the idea that war is absolutely bad. That's preventing you from even considering the possibility of higher order consequences of war having positive aspects. It's conceivable that warfare improved the human capability for advanced cooperation, motivated engineering advances, inspired great art, selected for stronger and healthier men, lead to beneficial gene flows between populations, and had other largely positive effects.
Warfare also provided the motivation (and the resources) for much better medical care. Major advances were made during each major conflict over the last 200 years.
I'm not having any trouble at all, I can entertain both the idea that war has advanced society despite other issues and the idea that it has not. It is, in fact, unclear to me.
I'm replying to a comment that says the idea that it has not is obviously impossible to entertain.
