Both sovereigns followed the policy of centralization in their respective kingdoms. In Castile the major problem was the reduction of the oligarchical nobility, for the middle classes had already been won over in great part when Isabella ascended the throne. Her success in reducing the lawless nobles has already been discussed; it only remains to point out the significance of the act by which she completed this task,--her incorporation of the masterships of the military orders into the crown. The principal element in the three great orders of Santiago, Calatrava, and Alcántara were the _segundones_ of great noble families and members of the lesser nobility. Not only by their military power but also by their numbers and wealth these orders constituted a potential danger to the crown unless their action could be controlled. An estimate of the year 1493 showed that there were 700,000 members and vassals in the order of Santiago, and 200,000 and 100,000 respectively in those of Calatrava and Alcántara. The first-named had annual revenues of some 60,000 ducats ($900,000), and the two last combined, some 95,000 ($1,425,000). With the masterships in royal hands the probability of civil strife was greatly lessened. [Sidenote: Increase of the royal authority and tendency toward unity in municipal life.] [Sidenote: Decline of the Castilian _Cortes_.] As regards the towns the Catholic Kings followed precisely the same practices which had been employed with such success in the previous era. It was rare, indeed, that they suppressed charters, but circumstances like those already recorded[52] enabled the _corregidores_ and other royal officers to exercise virtual control. Meanwhile, the process of unification was going on through the ordinances of the _Cortes_ and royal decrees, fortified by the unrecorded development of similarity in customs in Castilian municipal life. This was furthered by the representatives of the towns themselves, for royal and municipal interests were usually in accord. Noteworthy extensions of royal authority appeared in the subjection of local officials to the _residencia_ (or trial during a number of days after the completion of a term of office, to determine the liability of an official for the wrongful acts of his administration) and in the sending of royal _pesquisidores_, or enquirers (in cases of crime), and _veedores_ (inspectors), later more often called _visitadores_ (visitors), to investigate matters of government, such as the accounts of financial agents and the conduct of public officers. These institutions were later transferred to the Americas, becoming an important means of sustaining the authority of the mother country. In some instances the Catholic Kings resorted to force to reduce municipalities which were too autonomous in character, notably in the case of the _hermandad_ of the north coast towns, whose decadence dates from this reign.