I could reduce the inevitability of war to one concept, one word: 'Tyranny'. Another: 'Slavery'.
'Government', taken too far. 'Utopia' ('Dystopia'). Orwellianisms: Tyranny is liberty (liberty is tyranny). Slavery is freedom (freedom is slavery). Double-think. Double-speak.
Evolution is an energetic tree of branches and branching, it is not an energyless monolithic monstrosity. It isn't Aldous Huxley's 'A Brave New World'. If an energetic nature cannot divide (explode) outwardly in nova, it will divide (implode) inwardly in blackhole. Division will have its half of nature even if it has to rip it out of the guts of unity.
War has been a part of life from the beginning of life or life would never have expanded from mudhole to mudhole. Expansion from the mudhole for divisions and survivals, prosperities and evolutions, is revolutionary and is itself war (in never being anything like 'naked singularity').
You could say the reason "frontier" exists in the first place as a concept to be most devoutly wished for is to give division ("exodus") its half of nature so unity can keep its half. "Frontier" is itself a form of non-localizing war that gives peace a greater chance and measure of local being. There is a truism, "Grow or die" ("Birth or die") ("Expand or contract"), be energetic or entropic... spin your wheels and go places, or spin your wheels in place and go extinct. The historian of civilization, Will Durant, said in his brief "The Lessons Of History", that nature (life nature) has no use for organisms that cannot reproduce abundantly, that cannot or will not compete. Civilizations that are not fertile are not vital and, thus, mark themselves for extinction.
To live, itself, is actually the highest form of war. To die, itself, is actually the highest form of peace.
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"When the human race dies out, it will be because it was brainwashed to be so totally, completely, utterly safe that it no longer dared to keep on living, a risky business at best."