War: What is it good for?

War is one of the greatest human evils. It has ruined livelihoods, provoked unspeakable atrocities and left countless millions dead. It has caused economic chaos and widespread deprivation. And the misery it causes poisons foreign policy for future generations. But, argues bestselling historian Ian Morris, in the very long term, war has in fact been a good thing. In his trademark style combining i...