In the second half of the sixteenth century, in accordance with the centralization and reorganization of the administrative and military apparatus desired by Philip II in the States of the Iberian Monarchy, military defense was reorganized in the Kingdom of Sardinia, against the threatened Franc-Turkish invasion of the Island. Until that time, in fact, the defense of the Kingdom was based only on the modernization of the main Royal Cities fortifications. The inspiring principle of this strategy was the medieval one: to defend the Kingdom, it would have been enough to defend the Royal Cities of Cagliari and Alghero. Instead, starting from the Parliament wanted in 1558 by Philip II and summoned by the viceroy Alvaro de Madrigal, attention is also paid to the defense of the coastal perimeter of the whole island. In this Parliament, convened with the sole purpose of providing for the defense of the Kingdom against the looming Franc-Turkish threat, the foundations are laid for the reorganization of the administrative apparatus of the Kingdom, limiting the centrifugal tendencies of local feudalism; but above all, they are laid the foundations for the creation of a homogeneous defense system, abandoning the extemporaneous initiatives taken up to that time. By the end of the century, reports for the construction of a static defense system will be commissioned and the Royal Administration of Towers will be established, with the task of building, arming and maintaining the static defense system.