Los nidos C.G.I.S. y los fortines conjugados

In this paper we present some standardized fortification models built by the National Army during the Spanish Civil War. They appear in the bibliography from the first moment but their origin had not been investigated so far, exposed their features, and not even getting deeper in their study. The C.G.I.S. nests were designed by the Salamanca Engineer Command in 1937 and were built on different fronts (at least in the Center, Aragon and Andalusia). They had a mixed concrete and metal structure. Some time later, on the Madrid front, a defensive redoubt model (a blockhouse model) called «conjugate» was generated, centered on a fort composed of 4 joined C.G.I.S. nests. It was called «conjugate model»(modelo conjugado). In this paper, the archival documentation located on these works is exposed, which is complemented by that one obtained by the analysis of the ma-terial remains used mainly to understand the construction process.