Spanish Civil War  (1936-39), military revolt against the Republican government of Spain, supported by conservative elements within the country. When an initial military coup failed to win control of the entire country, a bloody civil war ensued, fought with great ferocity on both sides. The Nationalists, as the rebels were called, received aid from Fascist Italy and Nazi Germany. The Republicans received aid from the Soviet Union, as well as from International Brigades, a great number of volunteers who came from other European countries and the United States.

The war was an outcome of a polarization of Spanish life and politics that had developed over previous decades. On one side were most of the Roman Catholic Church in Spain, important elements of the military, most landowners, and many businessmen. On the other side were urban workers, most agricultural labourers, and many of the educated middle class. Politically their differences often found extreme and vehement expression in parties such as the Fascist-oriented Falange and the militant left-wing anarchists. Between these extremes were other groups covering the political spectrum from monarchism and conservatism through liberalism to Socialism, including a small Communist movement divided among followers of the Soviet leader Joseph Stalin and his archrival Leon Trotsky. Assassinations and other acts of violence were not uncommon. In 1934 there were general strikes in Valencia and Zaragoza, fighting in Madrid and Barcelona, and a bloody rising by miners in Asturias that was suppressed by troops led by Gen. Francisco Franco. A succession of governmental crises culminated in the elections of Feb. 16, 1936, which brought to power a Popular Front government supported by most of the parties of the left and opposed by the parties of the right and what remained of the centre.

A well-planned military uprising began on July 17, 1936, in garrison towns throughout Spain. By July 21 the rebels had achieved control in Spanish Morocco, the Canary Islands, and the Balearic Islands (except Minorca) and in the part of Spain north of the Guadarrama mountains and the Ebro River, except for Asturias, Santander, and the Basque provinces along the north coast and the region of Catalonia in the northeast. The Republican forces had put down the uprising in other areas, except for some of the larger Andalusian cities, including Seville, Granada, and Córdoba. The Nationalists and Republicans proceeded to organize their respective territories and to repress opposition or suspected opposition. A minimum estimate is that more than 50,000 persons were executed, murdered, or assassinated on each side--an indication of the great strength of the passions that the Civil War had unleashed.

The captaincy of the Nationalists was gradually assumed by General Franco, leading forces he had brought from Morocco. On Oct. 1, 1936, he was named head of state and set up a government in Burgos. The Republican government was headed, beginning in September 1936, by the Socialist leader Francisco Largo Caballero. He was followed in May 1937 by Juan Negrín, also a Socialist, who remained premier throughout the remainder of the war and served as premier in exile until 1945. The president of the Spanish Republic until nearly the end of the war was Manuel Azaña, an anticlerical liberal.

Each side, seeing itself too weak to win a quick victory, turned abroad for help. Germany and Italy sent troops, tanks, and planes to aid the Nationalists. The Soviet Union contributed equipment and supplies to the Republicans, who also received help from the governments of France and Mexico. About 40,000 foreigners fought in the International Brigades on the Republican side, and 20,000 others served in medical or auxiliary units.

By November 1936 the Nationalists had advanced to the outskirts of Madrid. They laid siege to it but were unable to get beyond the University City area. They captured the Basque northern provinces in the summer of 1937 and then Asturias, so that by October they held the whole northern coast. A war of attrition began. The Nationalists drove a salient eastward through Teruel, reaching the Mediterranean and splitting the republic in two in April 1938. In December 1938 they moved upon Catalonia in the northeast, forcing the Republican armies there northward toward France. By February 1939, 250,000 Republican soldiers, together with an equal number of civilians, had fled across the border into France. On March 5 the Republican government flew to exile in France. On March 7 a civil war broke out in Madrid between Communist and anti-Communist factions. By March 28 all of the Republican armies had begun to disband and surrender, and Nationalist forces entered Madrid on that day.

The number of persons killed in the Spanish Civil War can be only roughly estimated. Nationalist forces put the figure at 1,000,000, including not only those killed in battle but also the victims of bombardment, execution, and assassination. More recent estimates have been closer to 500,000 or less. This does not include all those who died from malnutrition, starvation, and war-engendered disease.

The political and emotional reverberations of the war far transcended those of a national conflict, for many in other countries saw the Spanish Civil War as part of an international conflict between--depending on their point of view--tyranny and democracy, or Fascism and freedom, or Communism and civilization. For Germany and Italy, Spain was a testing ground for new methods of tank and air warfare. For Britain and France, the conflict represented a new threat to the international equilibrium that they were struggling to preserve, which in 1939 collapsed into World War II.