The Spanish Civil War, fought between 1936–39, provided an opportunity for many European countries to evaluate new technologies and tactics, including armored warfare. At the beginning of the war, the Nationalist and Popular Fronts each possessed only five Renault FT light tanks, although these were soon reinforced with imported materiel. Italy began supplying Nationalist Spain with L3/35 light tanks in August 1936. The Soviet Union soon followed suit by supplying the Popular Front with T-26 tanks in October 1936. Germany sent its first shipments of Panzer I light tanks to the Nationalist Front in September 1936. During the war, France and Poland provided the Popular Front with a number of additional FT light tanks. A considerable number of tanks delivered to the Popular Front were subsequently captured; many of these were put into service against their former owners.
The Nationalist and Popular armies also designed and manufactured a number of their own tanks. The Nationalists, for example, began the war with three Trubia A4 prototypes, manufactured before the beginning of the conflict. They also completed the first prototype of the Verdeja light tank. This was designed to overcome the shortcomings of tanks provided by the Germans and the Italians, as well as Soviet tanks captured from the Popular Front. Popular Front production of armored vehicles was segmented throughout different areas of Spain. In the north, between 15 to 20 Carro Trubia-Naval tanks were manufactured at the factory in Sestao, conversely the Trubia factory had built only a single model Landesa tank. In Catalonia, two tanks were produced by the Maquinaría Moderna factory in Sant Sadurní d'Anoia. Though the Popular Front designed and manufactured many more armored fighting vehicles than the Nationalists, this ultimately worked in the Nationalists favor as the factories and their production lines were captured intact during the war.
^Manrique & Molina (2006), p. 324; Manrique & Molina claim that Republican Spain received two shipments of 16 FT tanks each, while García tracks only a single shipment of 16 tanks to Republican Spain from Poland.
^Molina & Manrique (2007), p. 36; Molina and Manrique (2007) mention that the Nationalist Front, out of a total of 80 which had been deployed into front line Nationalist tank units, had put into front line service 49 captured T-26s, while another 11 required minor reconstruction, another 10 required return rollers (wheels used keep the top of the track running straight) and 10 more were scrapped.
García, Dionisío (March 2008). "Trubia: El Primer Carro de Combate Español". Serga (in Spanish) (Madrid, Spain: Almena) (52).
García, Dionisío (September 2004). "Renault FT 17 en España (2): La Guerra Civil". Serga (in Spanish) (Madrid, Spain: Almena) (31).
Hofmann, George F. (1 January 1998). "The Tactical and Strategic Use of Attaché Intelligence: The Spanish Civil War and the U.S. Army's Misguided Quest for a Modern Tank Doctrine". Journal of Military History (Society for Military History) 62 (1).
Manrique, José María; Lucas Molina Franco (2006). Las Armas de la Guerra Civil Española (in Spanish). 28002 Madrid: La Esfera de los Libros. ISBN84-9734-475-8.
de Mazarrasa, Javier. Carro de Combate Verdeja (in Spanish). Barcelona, Spain: L. Carbonell. ISBN84-86749-02-6.
Molina, Lucas; José María Manrique (December 2007). Blindados Soviéticos en el Ejército de Franco (in Spanish). Spain: Galland Books. ISBN978-84-6121221-7.