The Spanish Civil War, in which Auden participated, began on July 18, 1936. The conflict was between the leftist Republican government and the right-wing Spanish military (referred to as the Nationalists) led by General Francisco Franco.
Elections held in 1931 brought the Republicans into office with a strong majority. The Spanish King Alfonso XIII fled into exile when voters abolished the monarchy. Thus began the Second Republic, in which liberals and moderate socialists ruled (the First Republic was short-lived in the 1870s). Liberal reforms were widespread in the first two years, and Catalonia and the Basque region received almost complete autonomy. The regime's enemies were gathering after their defeat; they included the Church, the landed aristocracy, and the military. In November 1933 conservative forces took back control of the government. The socialists launched their own revolution in Asturias, and the Catalan nationalist rebelled in Barcelona. In response, the powerful General Franco crushed this October Revolution, and for his victory was appointed army chief of staff in 1935.
In February 1936 liberals returned to power in the Popular Front, a leftist coalition. Franco was sent out of the country to a command in the Canary Islands, Africa. His absence did not preclude conservatives in government from plotting to seize power. Franco agreed to their conspiracy. The chosen date would give the Army of Africa time to secure Morocco before being sent to the Andalusian coast by the navy. The plans were discovered on July 17, however, and the rebels were pushed into action prematurely. The Nationalists took Melilla, Ceuta, and Tetuan. Their efforts were aided by conservative Moroccan troops.
Republican government officials heard of the rebellion but were not effective in preventing its spread to mainland Spain. The following day, July 18, garrisons rose in revolt throughout Spain and were countered by laborers and peasants. The Republicans' refusal to grant the lower classes weapons initially led to Nationalist victories. In conservative regions there was little bloodshed when the Nationalists took over, but in other places like Bilbao they largely failed to take over. The navy was mostly immune to the Nationalist efforts.
Franco succeeded in bringing his Army of Africa to Spain and took over large parts of Republican-held areas in central and northern Spain, and Madrid was put under siege in November 1936.
Franco unified the Nationalist forces under the Fascist Party, and the Republicans were influenced by the communists. In terms of foreign support, Germany and Italy aided Franco, while the Russians aided the Republicans. America and Britain did not get involved officially. However, radicals and activists from those countries organized International Brigades to aid the Republicans, which helped secure Madrid.
By 1938 the Nationalists had cut Republican territory into two areas. Franco attacked Catalonia, and Barcelona fell in January 1939. The Republicans finally tried to sue for peace but Franco refused, and they surrendered Madrid on March 28, 1939. Over one million people lost their lives in the war, and Franco ruled as a dictator until his death in 1975.
Auden was not the only intellectual who volunteered for the Republican cause during the war; Ernest Hemingway and George Orwell also participated.
Auden was in Spain for about seven weeks, from mid-January to early March 1937. For an attempt to chronicle Auden’s time in Spain, see Nicholas Jenkins, “Auden and Spain,” in the first Auden Studies volume (with Katherine Bucknell), W. H. Auden: "The Map of All My Youth": Early Works, Friends and Influences (Oxford, Clarendon Press, 1990), 88-93, available at http://www.stanford.edu/~njenkins/archives/jenkins-auden_and_spain.pdf.