Only in war does a human being feed the instinctive desire to destroy the life around them. It is only directed at life; its nature depends on it.
Then what makes it so grandiose in its beauty? When war ends, societies are destroyed. Those who fought in a war and survived it now have to live with what has been taken from them through its destruction. These people, tormented by the apex of human destruction and violence, desire peace much more than those who have never fought in a war. When the war ends, the greatest peace between the survivors can be achieved - human aggressions become a minimum.
After a war, people then become less focused on aggression and by being motivated most by peace they desire to optimistically rebuild their society as best and peacefully and morally as possible. This is where the beauty is seen. People learn from the mistakes of their past and apply new ideas in the hopes that the mistakes that lead to the greatest horrors of human nature can be avoided; and they rebuild and re-engineer their societies with the inspiration that the same problems won't occur again - that all actions have meaning and as long as we learn from our mistakes, we will construct societies that create a greater and longer-lasting peace.
But as time goes on, the memory of a war fades in human minds. As time goes on, aggressions start increasing. Soon enough aggressions become too great and at its apex we encounter war again. Thus the cycle repeats. And it's beautiful because in the wake of its destruction it leaves an intelligent imprint in time where humanity rebuilds things differently and better than before and tries to improve society. It is only in the absence of war do societies become most stagnate.
But with this in mind, is it possible to create a society that can appreciate and understand the peace of minimum aggression, while still carrying the creative intelligence of destroying and rebuilding? Or do human beings naturally thrive on aggression and is war a necessary evil to temporarily abate our dark never satisfied aggressive desires that eventually overwhelm and aghast us to try and change our societies with inherently futile hopeful optimism? Or are we forever doomed to be simply like bacteria in a petri dish programmed to destroy parts of itself when the dish becomes full in an attempt to fruitlessly change and grow again to only fill the petri dish once again?
*By saying that a war has ended, I mean that a transgressor has been defeated. If a country invades another, but plays the role of a transgressor, then that country will always be at war until it is defeated or the country invaded is completely dissolved or destroyed.