If there is a general sense among the people of the world that they want capitalism together with free international trade, then that alone is a powerful incentive to global peace. This is because it makes no sense to permit the international division of labor and complementary production to arise in the first place if there is a serious risk of war that will inevitably sever commercial ties.
In addition, nations linked by free trade tend to stay at peace, since it is not in anyone’s interest to harm his trading partners. Therefore, it is not “democracies” that do not go to war with each other, but capitalist nations united by trade. As always, liberty is far more important than democracy.
Finally, there is the Misesian point that a free economy corrupted by the state into making weapons of destruction is a contradiction, since these weapons end up being so powerful and efficient as to be able to annihilate the entire planet.
As a machine gun enables an individual murderer to be “efficient,” so capitalism can make the state expert at killing and destroying whole nations.
Capitalism then demands a conscious ideological effort of all good people toward peace, lest this most progressive system of production perverted into militaristic mass murder will doom us all.