ABSTRACTOnce Portugal had risen up aganist the Austrias, from 1640 on, the Spanish-Portuguese "Raya" (border) suffers long periods of invasions, assaults, robberies, sieges, battles... renewed in the early eighteenth centrury, in the middle of it, and again at the begining and a few years later in the first two decades of the nineteenth century.Of the various invasion corridors along the border, the Madrid-Lisbon line will have a key role in the confrontations, leading to a strengthening of their vanguard and rearguard populations, especially in Portugal. Bastioned artillery and fortifications, forts and watchtowers will be fundamental in territorial defense.
KEYWORDS: Spanish and Portuguese Raya, invasion corridors, peninsular conflict corridor Madrid –Lisbon, border fortifications, fortified vanguard, fortified rearguard.