I'm no historian, so this is a very rough synthesis:
In history there's a handful of cases where there have been what are viewed as probably warless societies. Honestly I wouldn't say they fared any worse than warring states. Indus Valley Civilization, Rapa Nui Civilization, Early Sumeria... I'm sure there's countless others in reality but those are what I recall off the top of my head.
I find it difficult to actually piece together a narrative where war is actually a necessity. Empire itself, abstracted, is really just the displacement of toil which isn't a "necessary evil" by any means. And by far and large that is what virtually all war has been predicated on up to World War 2 which justified itself with teleological underpinnings like Marxism and Fascist ideologies; perhaps a few exceptions being outright hostilities triggered by emotional kings.
Ultimately it's survivorship bias, but the surviving population is selecting for all the worst conceivable parameters, which in turn has perverted our whole understanding of civilization. It's made it seem as if war is necessary, that defense strategies and assets must be in place, etc... I don't think this is really the case, but creating a policy system that is totally forbidding of the powers necessary to conjure the public force is a difficulty in and of itself.
I do also suspect that people who do tow the line of government aren't self-contained individuals, they do themselves require laws, governance, and espouse things like inevitable war are exactly those predisposed to causing it, and they're projecting themselves.