General Franco took command of a conservative military rebellion in 1936 against the republican government in Madrid, which was supported by socialist groups. Both fascist Italy under Benito Mussolini and Nazi Germany sent troops to support Franco, while the government got support from the Soviet Union as well as from individual volunteers from several countries. The war was determined when Franco conquerred Catalonia in January/February? 1939. Madrid was sieged without resistance on March 28, 1939.
See also Guernica, History of Spain.