© Getty Images

Victory for the Popular Front -

The election of February 16, 1936, brought to power in Spain a leftist Popular Front government. Republicans, supported by the Soviet Union, backed the victorious coalition. Republican supporters are pictured in Madrid celebrating the new government.

© Getty Images 

Nationalist response -

Fascist and extreme-right forces—supported by Nationalists—responded in July 1936 with an army mutiny and coup attempt. The Nationalists were backed by Nazi Germany and Fascist Italy.

© Getty Images

Manuel Azaña (1880–1940) -

The most prominent leader of the Republican cause was Manuel Azaña. He served as Prime Minister of the Second Spanish Republic (1931–1933 and 1936), and organizer of the Popular Front in 1935. Azaña was also the last President of the Republic (1936–1939).

© Getty Images 

General Francisco Franco (1892–1975) -

Heading the military uprising was General Francisco Franco. He led the Nationalist forces in overthrowing the Second Spanish Republic.

© Getty Images 

A divided nation -

The army mutiny and coup attempt quickly escalated into a civil war. Spain was left militarily and politically divided. Pictured are Republican militia fighters at the beginning of the conflict.

© Getty Images 

Civil war breaks out -

Civil war broke out in Spain on July 17, 1936. Pro-Nationalist forces were mobilized across the country. Here, troops march through San Sebastián (Donostia) in the Basque region of northern Spain after seizing it from the Republicans in September.

© Getty Images 

The Nationalists attack -

The Nationalists took control of a number of cities, including Pamplona, Burgos, Zaragoza, Valladolid, Cádiz, Córdoba, and Seville. In this image, volunteers are recruited into the Nationalist army in Salamanca.

© Getty Images 

Government remains in control -

However, Republican forces held Spain's most important cities, places like Barcelona, Valencia, Bilbao, Málaga, and, crucially, the capital Madrid. These remained under government control. Pictured are anti-fascist troops parading through Barcelona.

© Getty Images 

Polarized society -

Polarization of Spanish life and politics had developed over previous decades. But the divisions created by the civil war turned neighbor against neighbor. The Republicans were supported by various communists and socialist parties and militant anarchists, broadly represented by urban workers, most agricultural laborers, and many of the educated middle class. Pictured are Republican civilians raising a barricade in Barcelona.

© Getty Images 

Right-wing support -

The Nationalist group was supported by a number of Catholic conservative and religious groups, monarchists, and the fascist-oriented Falange political party. Pictured in the same city, Barcelona, are pro-Franco supporters.

The Soviet Union contributed equipment, supplies, and troops to the Republicans, who also received help from the Mexican government.

© Getty Images 

Help from Hitler -

Franco, meanwhile, turned to Adolf Hitler. Nazi Germany and Fascist Italy sent troops, tanks, and, notably, planes, to aid the Nationalists. Franco is pictured meeting Hitler in Berlin in late 1936.

© Getty Images 

Clash of ideology -

Political ideology pitted the left against the right. More precisely perhaps, the war was seen by many in Spain as a struggle between state centralism and regional independence, and authoritarianism against the freedom of the individual. Here, communist demonstrators carry placards with images of Stalin and Lenin.

© Getty Images 

Prelude to the Second World War -

The Spanish Civil War is sometimes described as a prelude to the Second World War. As it progressed, many foreign powers supported different sides of the conflict. Pictured are two Republican anarchist militia fighters on the streets of Barcelona.

Around 40,000 foreigners fought on the Republican side in the International Brigades. Volunteers came from countries as diverse as France, Ireland, Poland, Canada, and the United States. The group from America were known as the "Lincoln Brigade," seen here departing from New York City bound for Europe.

© Getty Images

Ernest Hemingway -

The civil war was widely reported on. Among the foreign correspondents covering the Republican cause was American novelist Ernest Hemingway, seen here in 1937 low in the trench in the center of the image. Hemingway would later write a fictionalized account of his time in Spain, published in 1940 as the novel 'For Whom the Bell Tolls.'

© Getty Images 

George Orwell -

Another celebrated writer covering the conflict was British author George Orwell. He is the tall figure standing at the left of this photograph, part of a POUM militia guard group (Workers' Party of Marxist Unification) in Barcelona in 1936. Orwell would later find fame as the author of 'Animal Farm' (1945) and 'Nineteen Eighty-Four' (1949), among other novels.

© Getty Images 

Nationalist sympathizers -

Besides those from Germany and Italy, international volunteers from Portugal, Morocco, and also from France fought on the side of the Nationalists. Notable figures who supported Franco, albeit discreetly, included British novelist J.R.R. Tolkien and American writer Gertrude Stein.

© Getty Images

The Condor Legion -

Nazi Germany's military aid for Franco extended to the establishment of the Condor Legion. Comprised of elements from the Luftwaffe and Wehrmacht, the unit was responsible for one of the most infamous atrocities in the entire conflict. Pictured is Herman Goring reviewing the Condor Legion.

© Getty Images 

Bombing of Guernica - On April 26, 1937, the Basque town of Guernica was aerial bombed by the Condor Legion and Mussolini's Aviazione Legionaria. Up to 400 civilians died in the attack, though the exact number of casualties has never been established. The bombing is commemorated in the famous anti-war painting 'Guernica' by Pablo Picasso.

© Getty Images 

Bilbao falls -

The bombing of Guernica was part of Operation Rügen. The suppression of Republican resistance opened the way to Franco's capture of Bilbao (pictured) and his victory in northern Spain.

© Getty Images 

Battle for Teruel -

After securing northern Spain, the Nationalists turned southeastwards to the Republican-held city of Teruel. The subsequent Battle of Teruel, fought  between December 1937 and February 1938 during the worst Spanish winter in 20 years, was one of the bloodiest engagements of the entire conflict, with both factions together suffering 110,000 casualties. Teruel eventually fell to Franco's forces, the battle becoming the military turning point of the war.

© Getty Images

Advance on Barcelona -

After Teruel, the Nationalists deployed their forces further south, reaching the Mediterranean in April 1938. Franco's sights were firmly set on Barcelona.

© Getty Images 

Isidora Ibárruri Gómez (1895–1989) -

By September 1938, all international volunteers had been withdrawn from Spain. The following month, remaining members of the International Brigades were given a farewell parade in Barcelona. Saluting them was Republican politician Isidora Ibárruri Gómez, better known as la Pasionaria ("the Passionflower"). Her famous send-off speech included the words: "You can go proudly. You are history. You are legend. You are the heroic example of democracy’s solidarity and universality." 

© Getty Images

Beginning of the end -

Franco's troops conquered Catalonia in a whirlwind campaign during the first two months of 1939. First to fall was Tarragona, on January 15. On January 26, Barcelona surrendered. Girona was captured on February 2. On February 27, the United Kingdom and France recognized the Franco regime.

© Getty Images 

The Republican retreat -

By the end of February 1939, 250,000 Republican soldiers, together with an equal number of civilians, had fled across the border into France.

© Getty Images 

Madrid falls -

One prize remained: Madrid. Besieged by Nationalist forces since 1936, and with the Republican government already in exile in France, the Spanish capital finally fell on March 28, 1939.

© Getty Images

The war ends -

With Madrid in ruins, and with all of the Republican armies either disbanded or having surrendered, the Spanish Civil War was over.

© Getty Images 

A dictatorship begins -

The Nationalists' victory over the Republicans ushered in a dictatorship headed by Franco that would last nearly 40 years. Six months later, the Second World War broke out. Spain remained neutral throughout that conflict, but supplied economic and military assistance to the Axis powers.

© Getty Images 

Counting the cost -

The number of persons killed in the Spanish Civil War remains unclear. The figures vary from one million to 250,000 combat-related deaths. They do not include all those who died from malnutrition, starvation, and war-engendered disease. Numerous atrocities were committed by both sides during the conflict, including summary executions. Killings continued under Franco's rule long after hostilities were supposed to have ended. Mass graves of those murdered are being uncovered today, with the political and emotional consequences of the war still reverberating throughout the country.

See also: History's most notorious prisoner-of-war camps

© Getty Images