Humans are violent territorial animals. As this is instinctive along with banding together into groups for mutual protection, like packs or herd of animals and shoals of fish, it will never change.
The most dangerous animal to man is man.
Ah, now Rods2 you have hit on the prime problem; man's natural state.

Have you read Leviathan, Penguin Books, first published 1651, by the philosopher Thomas Hobbs (1588-1679)? It, in my opinion, correctly summarizes, chapter 13, page 185-188, mans weakness for "warre", and also being in a constant state of "warre", being his natural determination. The book explains far more, but this particular section hits on the main issue.
Thanks, for that reference as I haven't read his book, but I will now do so, probably over Christmas. I very good at skim reading, but you can't do that with old English, so it will take longer than normal. For those interested where the book is copyright free, this is the link:
http://manybooks.net/titles/hobbesthetext02lvthn10.html"From Equality Proceeds Diffidence From this equality of ability, ariseth equality of hope in the attaining of
our Ends.
And therefore if any two men desire the same thing, which neverthelesse they cannot both enjoy,
they become enemies; and in the way to their End, (which is principally their owne conservation, and
sometimes their delectation only,) endeavour to destroy, or subdue one an other. And from hence it comes to
passe, that where an Invader hath no more to feare, than an other mans single power; if one plant, sow, build,
or possesse a convenient Seat, others may probably be expected to come prepared with forces united, to
dispossesse, and deprive him, not only of the fruit of his labour, but also of his life, or liberty. And the Invader
again is in the like danger of another."
Very well put in the paragraph above. I also like how Science was viewed at the time in this sentence: "setting aside the arts grounded upon words, and especially that skill of proceeding upon generall, and infallible rules, called Science; which very few have, and but in few things; as being not a native faculty, born with us; nor attained, (as Prudence,) while we look after somewhat els". Where Science is: "infallible rules" - this is the first time I have seen it summed up so well in 2 words or you could sum up scientific research as: "The search for infallible rules".

If you want a very good philosophical book on the writing of military history and the mechanics of battles through the analysis of a number of famous ones, I recommend John Keegan's book "The Face of Battle". One of my hobbies is history particularly 20th century military history.