The 18th century was marked by important changes in the Royal Corps of Engineers. In 1718, the first Instructions and Ordinances for the Corps of Engineers are given, and for those individuals who went to America, their actions would be framed within the policy of the new reigning house, which highlights the policy aimed at maintaining and consolidating the domain relations over colonial territories, in which militaryengineers play an important role. During the second half of the 18th century, some members of the Corps of Engineers actively participated in territorial surveys in the northern part of the Viceroyalty of New Spain, leading to the foundation and relocation of numerous villages, presidios and missions, of which a significantnumber survived the various historical events During the last third of the century the expedition to Alta California takes place, in which the engineer MiguelConstanzó participates, in order to ensure the Hispanic presence in those remote territories, with the creation of the San Diego and Monterrey settlements. With different objectives, the engineer Nicolás de Lafora makes a visit to the northern presidios that lasts more than three years, which resulted in the “Reglamento e Instruccion para los presidios” to be formed in the New Spain Presidios Line; while the engineer Agustín López de la Cámara Alta participates in the inspection of the New Santander with the objective of knowing the situation and the development of a colonizing company carried out by José de Escandón. Of all these recognitions, and others, the military engineers left us detailed descriptions and an important cartography that allowed a broad knowledge of these territories, which in some cases motivated the intention to occupy and develop them economically, with unequal fortune.