spanish civil war
A civil war in Spain lasted between 17 July 1936 to 1 April 1939. The civil war is fought betwene the "Republicans" consists of the incumbent Spanish republican government and the "Nationalists" consists of Fascist-oriented monarchist led by Francisco Franco, who eventually became victorious and ruled over Spain until 1975.
The war is often viewed as a prelude to the World War II in Europe due to the two major powers at that time, the Soviet Union and the Nazi Germany backed the Republicans and the Nationalists sides in a proxy war.