The Spanish Civil War began on July 17, 1936, when generals Emilio Mola and Francisco Franco launched an uprising aimed at overthrowing the country's democratically elected republic. The Nationalist rebels' initial efforts to instigate military revolts throughout Spain only partially succeeded. In rural areas with a strong right-wing political presence, Franco's confederates generally won out. They quickly seized political power and instituted martial law. In other areas, particularly cities with strong leftist political traditions, the revolts met with stiff opposition and were often quelled. Some Spanish officers remained loyal to the Republic and refused to join the uprising.
Within days of the uprising, both the Republic and the Nationalists called for foreign military aid. Initially, France pledged to support the Spanish Republic, but soon reneged on its offer to pursue an official policy of non-intervention in the civil war. Great Britain immediately rejected the Republic's call for support.
Faced with potential defeat, Franco called upon Nazi Germany and Fascist Italy for aid. Thanks to their military assistance, he was able to airlift troops from Spanish Morocco across to the mainland to continue his assault on Madrid. Throughout the three years of the conflict, Hitler and Mussolini provided the Spanish Nationalist Army with crucial military support.
Some 5,000 German air force personnel served in the Condor Legion, which provided air support for coordinated ground attacks against Republican positions and carried out aerial bombings on Republican cities. The most notorious of these attacks came on April 26, 1937, when German and Italian aircraft leveled the Basque town of Gernike (Guernica in Spanish) in a three-hour campaign that killed 200 civilians or more. Fascist Italy supplied some 75,000 troops in addition to its pilots and planes. Spain became a military laboratory to test the latest weaponry under battlefield conditions. Continue reading from US Holocaust Memorial Museum
Spanish Civil War (Britannica)
Spanish Civil War Breaks Out (History)
Francisco Franco: Biography (Britannica)
The Battle Over the Memory of the Spanish Civil War (Smithsonian)
In Many Ways, Spanish Civil War Was 'The First Battle Of WWII' (NPR)
Francisco Franco's Rise to Power (History)
Social Revolution and Civil War in Spain (National WW2 Museum New Orleans)
Looking Back on the Spanish War (Orwell Foundation)
Spain Welcomes Back Descendants of Civil War Exiles (VOA News)
Gathering the Genetic Testimony of Spain’s Civil War Dead (Scientific American)
Spanish Civil War: The Child Refugees Britain Didn't Want (BBC)
Eight Decades After Spain's Civil War, a Controversial Monument Still Haunts the Country (Time)
The Spanish Civil War - When Fascism Won (Into the Shadows; YouTube)