before WWII the powers had conflicting colonial ambitions, now its a post colonial world, so what matters is access to resources (these you can again buy with money, but the fight is over conditions and price).

I think there were several transitions that made the world a more civil place: one was the realization that free labor is better than forced /slave labor, the other one that you can do without colonies. (There was also the axial age, but that was along time ago)