The Spanish Civil War was a major conflict that devastated Spain from 17 July 1936 to 1 April 1939. It began after an attempted coup d'état by a group of Spanish Army generals against the government of the Second Spanish Republic, then under the leadership of president Manuel Azaña. The nationalist coup was supported by the conservative Spanish Confederation of the Autonomous Right (Confederación Española de Derechas Autónomas, or C.E.D.A), monarchists known as Carlist groups, and the Fascist Falange (Falange Española de las J.O.N.S.). The war ended with the victory of the rebel forces, the overthrow of the Republican government, and the founding of a dictatorship led by General Francisco Franco. In the aftermath of the civil war, all right-wing parties were fused into the state party of the Franco regime.

Republicans (republicanos) were supported by the Soviet Union and Mexico, while the followers of the rebellion, Nationalists (nacionales), received the support of Fascist Italy and Nazi Germany, as well as neighbouring Portugal. Although the United States was officially neutral during the conflict, major American corporations such as Texaco, General Motors, Ford Motors and The Firestone Tire and Rubber Company greatly assisted the Nationalist rebels with their constant supply of trucks, tires, machine tools and fuel.

The war increased international tensions in Europe in the lead-up to World War II, and was largely seen as a proxy war between the Communist Soviet Union and Fascist states Italy and Germany. In particular, new tank warfare tactics and the terror bombing of cities from the air were features of the Spanish Civil War which played a significant part in the later general European war.

The Spanish Civil War has been dubbed as "the first media war", with several writers and journalists covering it wanting their work "to support the cause". Foreign correspondents and writers covering it included Ernest Hemingway, Martha Gellhorn, George Orwell and Robert Capa.

Like most civil wars, it became notable for the passion and political division it inspired, and for atrocities committed on both sides of the conflict. The Spanish Civil War often pitted family members, neighbors, and friends against each other. Apart from the combatants, many civilians were killed for their political or religious views by both sides, and after the war ended in 1939, Republicans were persecuted by the victorious Nationalists.

An estimated total of 300,000+ people lost their lives as a consequence of the war. Out of them probably 120,000+ were civilians executed by either side.