What became known as the Spanish Civil War began on 17 July 1936 when a group of right-wing generals staged a military coup, aimed at overthrowing Spain's democratically elected government. The coup was supported by military units in many cities around Spain. However, some of the country's biggest cities, such as Madrid, Barcelona and Bilbao, remained under government control.
18 July 1936: Women plead for the lives of prisoners in Seville during the military coup that turned into the Spanish Civil War Public domain July 1936: Burned out cars are seen on a street after Franco's Nationalist uprising was defeated in Barcelona. The city eventually fell to the Nationalists in 1939 Keystone/Getty Images July 1936: Male and female militia fighters on the march at the beginning of the Spanish Civil War Keystone/Getty Images
Within days of the coup, Hitler and Mussolini intervened on the side of the insurgent generals. The Soviet Union came to the aid of the Loyalists, also known as the Republican forces. Britain, France and the US decided to remain neutral, even imposing – and enforcing – an embargo on the sale of arms to the Republic.
The battle for control of Spain turned into a horrific conflagration that lasted almost three years. The new medium of photojournalism brought horrifying images of the conflict into homes around the world. In an unprecedented display of international solidarity, some 35,000 volunteers from 50 nations joined the International Brigades and risked life and limb to defend the Republic.
From their strongholds in the south and west, the Nationalists – supported by Italian and Moroccan troops – advanced northwards, capturing cities from Republicans weakened by the embargo. Barcelona and the rest of Catalonia fell in early 1939, and Franco's troops marched into Madrid in April.
1936: People run to the nearest shelter Unknown artist Circa 1936: Nationalist troops shelter behind a wall on the Sierra de Guadarrama front, while they engage government troops during the advance on Madrid Keystone/Getty Images Circa 1936: Republicans fight on a street of an unidentified town against Nationalist forces AFP Circa 1936: General Franco, Chief of Staff Barroso and Commander Carmenlo Medrano look at a map AFP Circa 1936: A young Republican marches in a street of an unidentified village AFP Circa 1936: Female snipers, fighting for the government forces, are pictured in action during the Spanish Civil War Keystone/Getty Images Circa 1936: Scenes of destruction along the roads at the height of the Spanish Civil War Three Lions/Getty Images Circa 1936: Refugees walk up a mountainside. Many thousands of Spanish families crossed the Pyrenees to reach France Keystone/Getty Images Circa 1936: Refugees from the Spanish Civil War pack the roads to Perpignan in France. They were dispatched to rudimentary internment camps Three Lions/Getty Images 5 August 1936: Spanish Civil War refugees arrive in Gibraltar Derek Berwin/Fox Photos/Getty Images 10 August 1936: Residents of Gibraltar and Spanish refugees watch the bombardment of Algeciras Fox Photos/Getty Images 6 September 1936: A Republican farmer defends a farm on the outskirts of the Basque city of Irun against Nationalist forces. A comrade lies dead by his side Keystone/Hulton Archive/Getty Images 6 September 1936: Journalist Raymond Walker risks his life by dashing across the International bridge from Hendaye in France, to Irun in Spain, under a hail of bullets, to save a baby Horace Abrahams/Getty Images 8 September 1936: Republican militia men search through the wreckage of their barracks in Madrid after it was bombed Fox Photos/Getty Images 13 September 1936: Pro-Nationalist residents and troops celebrate on the streets following the capture of Donostia-San Sebastián Fondo Marín. Pascual Marín; Kutxa_Fototeka 28 September 1936: A mass is celebrated at the Alcazar in Toledo after the arrival of Nationalist troops that ended a 70-day siege by Republican forces AFP 7 November 1936: Nationalist troops escort captured Republican soldiers on the Samosierra front Keystone/Getty Images 9 November 1936: Moorish troops fighting with the anti-Communist forces rest after a victorious encounter in a suburb of Madrid Keystone/Hulton Archive/Getty Images Pro-Republic Basque fighters are seen in the town of Elgeta in the Basque Country, around 1936-1937 Public domain 13 November 1936: Citizens of Irun give the fascist salute during a parade after the city was taken over by the Nationalist troops Maeers/Fox Photos/Getty Images 13 November 1936: Boys and girls give the fascist salute in Irun after the city was captured by the Nationalists Maeers/Fox Photos/Getty Images 13 November 1936: Young boys with dummy rifles over their shoulders march in the streets of Irun in a parade organised by the Nationalists after they conquered the city Maeers/Fox Photos/Getty Images
11 February 1937: Republican forces lie in ambush in a village near Madrid Hulton Archive/Getty Images 2 April 1937: Nationalist troops loyal to General Franco advance, bayonets fixed, through the debris of houses at Madrid wrecked in air raids Hulton Archive/Getty Images Circa 1937: Republican soldiers carry a dead comrade at the Navacerrada Pass. This photo was taken by Gerda Taro, regarded as the first female photojournalist to cover the front lines of a war – and to die while doing so Gerda Taro The town of Guernica, after it was bombed by German and Italian aircraft on 26 April 1937, killing between 150 and 1,650 civilians Universal History Archive/UIG via Getty Images 25 May 1937: Some 4,200 Basque children arrive at Southampton aboard a liner, having been rescued from the horrors of the Spanish Civil War E. Dean/Topical Press Agency/Getty Images Circa 1937: Reporters mingle at the front line with Republican troops. Ernest Hemingway can be seen (in glasses) in the background London Express/Getty Images Circa 1937: Nationalist soldiers give the fascist salute Keystone/Getty Images Circa 1937: Bodies lie on a street after a sudden air raid Central Press/Getty Images 13 November 1937: Bodies of children await burial after a Nationalist air raid on their school in Barcelona Keystone/Getty Images
Circa 1938: Part of the city of Santander, which was severely damaged during fighting Three Lions/Getty Images Circa 1938: A member of the French frontier troops helps a family of refugees cross the border from Spain Keystone/Getty Images 24 November 1938: General Francisco Franco salutes during the singing of the Nationalist anthem at Burgos Cathedral 25 November 1938: Soldiers camouflage a car during the Spanish Civil War Hulton Archive/Getty Images 1939: Nationalist troops enter Barcelona in Carro Veloce CV33 tankettes, made in Italy Keystone/Getty Images January 1939: Nationalists in Barcelona rejoice at the arrival of General Franco's forces in the city. Barcelona was the last major Republican stronghold to fall to the Nationalists Keystone/Getty Images 30 January 1939: General Yagüe marches victoriously through Barcelona, four days after his troops had taken control of the city AFP 29 January 1939: A woman waits with her few remaining possessions at the French border at Perthus, after the authorities opened the borders to refugees from the Spanish Civil War, shortly after the fall of Barcelona Fox Photos/Getty Images 1939: Refugee families walk to safety during the Spanish Civil War Keystone/Getty Images February 1939: Two members of a rescue party assist an elderly woman fleeing the Spanish Civil War Topical Press Agency/Getty Images Circa 1939: Young refugees from the Spanish Civil War rest on the French border London Express/Getty Images 8 February 1939: Refugees are watched over by soldiers at an internment camp in Le Perthus, France, on the border with Spain Keystone/Getty Images Circa 1939: A dead horse, a casualty of the Spanish Civil War Evans/Three Lions/Getty Images 28 March 1939: Nationalist troops enter Madrid and are welcomed by the population Heinrich Hoffmann/ullstein bild via Getty Images 1 April 1939: A family searches through the rubble where their home in Madrid once was Hulton Archive/Getty Images 19 May 1939: General Franco presides over the victory parade in Madrid AFP
Historians estimate as many as 500,000 combatants and civilians were killed on the Republican and Nationalist sides in the war. Atrocities were committed on both sides. The victors under General Franco executed thousands more after the war. It is estimated that over 100,000 men and women were executed and buried in unmarked graves during the conflict.