OFcourse there will be war, no-one will disagree that humans are a type of animal. (Albeit "advanced".) And animals live for several things:
The sake of living.
To be stimulated. (Wether by sex, food, or just plain out leisure..)
And conflict. (Wether to protect themselves, others, or simply for the hell of it.)
These are our basic motivations as well, and sense we're an "advanced" species, we have no natural enemies, we know how to "avoid" more badass animals, make food out of lesser animals, make weapons to protect ourselves, we have no natural predator, only hostile fellow creatures.
Therfore, man has to become man's own worst enemy for the sake of balance between life and death, I can only immagine how much worst it would be if we never had wars, we'd be so overcrowded we'd suffocate life out of every other animal on the planet, and eventualy destroy ourselves anyway because of lack of balance.
Besides, war isn't THAT bad, it's so glorified and made to look like something it's not, ok, people die, people die all the time, bad feelings settle in, lots of evil-men get away, that happens all the time to, war just esculates the same problems we face everyday. If war was so HORRIBLE I doubt it would happen so much, someone, somewhere, is in a war as we speak, always, always, ALWAYS. There has been no point in time on Earth (as long as we were an "advanced" species anyway) where a war hasn't been going on SOMEWHERE.
I think those that spend so much time asking "what is war good for?" don't have thier priorities straight, ofcourse war is good for something, if it wasn't, our selfish-ass goverment wouldn't engage in it so much.. We as a SPECIES need to re-think what makes us tick, and how to view our situation, that has a larger impact on life then any simple war. Because people don't do that, we countinue to repeat our same mistakes over and over again. Frankly, such a species that's so "advanced" but can't get the picture the first couple times around deserves the anguish they receive from themselves..