Spain at the close of the fifteenth century had just completed a long process of unification, accomplished by a series of crusades, partly national and partly religious in character, within Iberian territory. Pride of race, skill in arms, and a truculent missionary Catholicism characterised the leading elements of the new Spanish State, especially in Castile, the dominant partner of the union. With the completion of reconquest the Crown was able to bring this intractable aristocracy of swordsmen more and more under military discipline and the centralised rule of law. The monarchy was strong and national in character; under the Catholic monarchs it achieved effective supremacy in both Church and State. It commanded the services not only of able soldiers and administrators but also of able theologians and legal and political theorists, so that the nature and purpose of government, as well as its effectiveness, were matters of public concern.

It is not surprising, therefore, that when Columbus discovered in the New World a new outlet for the restless energy of Spanish swordsmen, a strong and self-conscious imperialism quickly grew up at the Spanish court. After the failure of Columbus as autonomous governor of Española, the Crown stepped in to check the private exploitation which had reduced the colony to chaos and which seemed likely in time to exterminate the natives altogether. It is true that under Ferdinand the sharpest conflict appeared to be between exploitation of the Indians by the colonists, and the even more disastrous system of exploitation by Aragonese concessionaires at court; but this was a temporary tendency.