One of the first, and primary, needs of any society is the ability to sustain itself in the face of armed aggression from outside, or from armed insurrection or revolt internally. Every nation therefore has had to organize its military force and exercise strict control over the military power if it was going to have any chance of success. Looking at the movement towards a unified world-state or governing body, the need for a unified military control becomes even more important, if that is possible. Since every nation that would join into such a combine has its own military, together with its own cultural traditions, religious background, racial makeup, and economic model, the process starts from a widely distributed military capability at the beck and call of the natural nation-states that already have a history of existence and exercise of their power. If this power is not effectively centralised and brought under the control of the governing body of the world-state, there is the constant risk, even certainty, of military conflicts breaking out and spreading, thereby preventing ultimate stability of the new world-state.
Sri Aurobindo observes that the psychological unity and moral force of the societal grouping is the primary unifying factor, but in the end: “…since these motives may at any moment fail when revolting interests or sentiments are strong and passions run high, the governing body must have always the greatest military force at its command so as to overawe the constituent elements and prevent the outbreak of a disruptive civil war. Or if the civil war or rebellion comes about, as can always happen when the monarchy or the government is identified closely with one of the parties in a quarrel or is itself the subject of dissatisfaction and attack, then it must have so great a predominance of force behind it as to be morally sure of victory in the conflict. This can only be secured to the best possible perfection, — it cannot be done absolutely except by an effective disarmament, — if the whole military authority is centred in the central body and the whole actual or potential military force of the society is subjected to its undivided control.”
Sri Aurobindo, The Ideal of Human Unity, Part Two, Chapter 24, The Need of Military Unification, pp 205-206