Through civil wars and the weakness of the kings the power of the nobles, both socially and politically, appeared to increase. They did not confine their strife to opposition to the king, but fought one another incessantly, not for any political or other ideal, but mainly for personal reasons. Such was the nature of the wars, for example, between the Guzmán and Ponce families of Seville. As time went on, these intra-class struggles increased, being more numerous than ever in the fifteenth century. The nobility would have destroyed itself if the kings had known how to take advantage of the situation, but most of them failed to appreciate their opportunity. Sancho IV, Alfonso XI, Pedro I, and Henry III tried to reduce the nobles by direct attack, and Henry IV gave special attention to the development of a new nobility as a counterpoise to the old, but usually the kings dared to fight only indirectly, as by granting the petitions of the towns which involved a diminution of seigniorial authority. Two circumstances in addition to their political victories tended to secure the position of the nobles: the adoption of the law of primogeniture with regard to the succession to both their titles and their lands; and the increase in the territorial domains in the possession of the nobles. By the law of primogeniture the wealth of the family and the lustre of its name were given in charge of the eldest son, maintaining in this way the powerful position of the particular noble house. The second sons (_segundones_), in large measure disinherited, sought a career as members of the clergy or as soldiers. Henry II himself was partly responsible for the introduction of this new practice of the nobility, and he and later kings usually required that the lands granted by them to the nobles should be inalienable and subject to the law of primogeniture. The royal donations, which were especially great from the time of Henry II on, were usually of two kinds: _honores_ (honors), or grants of the fiscal rights which the king had in a specifically named place; and _tierras_ (lands), or grants of a fixed rent on a certain town or towns. Both forms were termed generally grants in _encomienda_. The nobles increased their holdings yet more by usurpations and private conquests. Early in the reign of Henry IV, for example, the Duke of Medina Sidonia and other nobles conquered territories of vast size from the Moslems, and these _latifundia_, (broad estates) have influenced even to the present day the economic life of Andalusia. [Sidenote: Decline of the military orders.]