The evolution of military power is one of the most important if underrated geopolitical changes happening in the world today. Throughout the 20th century, military power was the province of large nations. Machines dominated the battlefield, and the production of these machines, the materials that fueled them and the ordnance they used required access to complex factories and massive amounts of raw materials. This, in turn, required vast numbers of workers – and the housing and food the workers needed to function. An economy of this scale needed to produce large numbers of ships, planes, tanks and all other manners of wartime materiel, even as they required functioning economies outside the wartime economy, providing the basic necessities of life and, ideally, maintaining national morale.