These confrontations and contradictions created three sets of political problems: centralism versus localism; established central authority versus provincial rights and self-determination; the concentration or centralization of authority in the hands of a select few civilian and/or military leaders, responsible to the central authority, who made on the spot decisions and took action. Under the institutions and practices of civilized society, the select few were in a position to call in the military which was organized for emergency action and was constantly standing-by. The military was trained, disciplined and held a monopoly of weapons. Civilizations frequently begin as commonwealths or federations forged in the course of survival struggle. In any such struggle the military will of necessity play a major role. As the competitive survival struggle develops, one of the contending parties establishes its superiority by winning military victory. In the course of this struggle the commonwealth, a cluster of equals, yields place to the pattern of empire--a center of wealth and authority with its associates, subordinates and dependencies. The strong right arm of politics includes man-power, money and weapons. The politics of civilization faces a simple mandate: establish, stabilize and perpetuate a nucleus of wealth and authority; build around the nucleus a periphery of associates and dependencies. Historically, the process was a long one extending through generations and probably centuries. Throughout the struggle individuals must have the necessities of daily life. Community activities must be housed, equipped, staffed, supported. Pastoral and village life were based on a use economy. People produced what they needed and consumed their own products. Each tribe, family, village was a more or less self-sufficient unit. When they were threatened or invaded people defended themselves as best they could. At worst they abandoned their homes to the invaders and fled into the forests, mountains or deserts. Towns and cities, with their industries, trade, commerce, their permanent housing and capital equipment faced a radically different situation. Since they could not carry their wealth on their backs they must stay put and defend themselves or face irreparable losses. Defense required careful, extensive, expensive preparations: walls, equipment, stored food, personnel. Unless the city was sacked and burned during survival struggles it remained as a vantage point to be held at all costs. If surrendered and occupied by assailants, it was equally valuable to invaders who were prepared to settle down, take advantage of the site, the capital equipment and exploit the available manpower.