We will be misguided in our intentions if we point at one single thing and say that it will prevent war, unless, of course, that thing happens to be the will, the determination, and the resolve of people everywhere that nations will never again clash on the battlefield.
Thus society is born, as something required by nature, and (because this nature is human nature) as something accomplished through a work of reason and will, and freely consented to. Man is a political animal, which means that the human person craves political life, communal life, not only with regard to the family community, but with regard to the civil community.