States by secrecy: Cryptography and guerrillas in the Spanish Civil War
José Ramón Soler Fuensanta, Vicente Guasch Portas · Cryptologia · 2015
The Spanish Civil War revitalized a type of unconventional struggle that had already been seen for centuries in different conflicts in the Iberian Peninsula: guerrilla warfare. According to the new times, this kind of struggle was conditioned by a need for coordination and maintenance of the secrecy of operations performed. The systems used by the guerrillas to protect their communications have not been studied in detail. This is a brief study of the cipher methods used by the republican guerrillas, the most important and numerous in this fight, in the Spanish Civil War.