Geography, history, and technology have determined the way in which modern Western armed forces fight. Norman Davies wrote that the inhabitants of the Great European Plain, which stretches from the Atlantic to the Urals, could find no natural limits to the territory they chose to occupy. The peoples who settled on the plain had to fight for it. They had to learn the art of systematic military organization, so it comes as no surprise that the plain nourished the greatest military powers in Europe's history: France, Prussia, and Russia.

The modern system of states, and the characteristics of Western civilization, contributed greatly to the shaping of modern armed forces. Territorial expansion and survival of the state became the objectives of war. The Peace of Westphalia (1648), which gave birth to the modern state system, and the French revolution (1795) provided the political condition for armies based on militarized conscription. Conscription provided the state with an instrument to quickly mobilize mass armies for the defense of the homeland. Industrialization and the rapid rise in population in the decades following the French revolution provided the material basis for mass armies. Nevertheless, after the restoration of autocratic regimes in the early 19th century, the ruling classes feared the consequences of armed citizens. Particularly in France, Prussia, and Austria, this gave rise to a class of longer-serving professional officers who represented the autocratic political structures. This pattern became widespread throughout Europe. Conscription enabled the emerging industrialized liberal democracies to view their military potential in terms of national population size. Both geography and the system of Westphalia required large, standing armies. Conscripts became the most important source of manpower. Consequently, temporary armies led by nobles were gradually replaced by standing armies led by professionals.

The system was further developed with new technological and organizational innovations. The railway system made mass movement, or “strategic lift” in contemporary jargon, possible. The electric telegraph was part of a new communications network. Political control over mass armies from great distances, and tactical control of deployed forces, was thus greatly enhanced. Other innovations, such as bureaucratic staffs and national census systems, made possible the organization of mass armies.