The Peace of Westphalia (1648) marked the end of the Thirty Years' War and the beginning of the modern European state system. The development and evolution of the principles laid out in the Westphalian treaties made the territorially defined independent sovereign state the dominant political unit for managing and governing populations. Those principles also led to recognition of the state as the primary unit for interaction (including the "interaction" of war) between territorially bounded populations. By the end of the twentieth century, the state system had encompassed the entire globe.

An understanding of the relationship between religion, politics, and war begins with an analysis of regimes (Swanson 1967). A state governs a population by means of a regime. A regime is responsible for maintaining peace and securing justice within the territorial bounds of a state. A regime acts by exercising its own autonomous powers...