The international response to the Spanish Civil War included many non-Spaniards participating in combat and advisory positions. The governments of Italy, Germany and, to a lesser extent, Portugal contributed money, munitions, manpower and support to the Nationalist forces, led by Francisco Franco. Some nations that declared neutrality favored the nationalists indirectly. The governments of the Soviet Union and, to a lesser extent, France and Mexico, aided the Republicans, also called Loyalists, of the Second Spanish Republic. The aid came even after all the European powers had signed a Non-Intervention Agreement in 1936. Although individual sympathy for the plight of the Spanish Republic was widespread in the liberal democracies, pacifism and the fear of a second world war prevented them from selling or giving arms. However, Nationalist pleas were answered within days by Adolf Hitler, Benito Mussolini and António de Oliveira Salazar. Tens of thousands of individual foreign volunteers travelled to Spain to fight, the majority for the Republican side.

Francisco Franco Bahamonde was a Spanish military general who led the Nationalist forces in overthrowing the Second Spanish Republic during the Spanish Civil War and thereafter ruled over Spain from 1939 to 1975 as a dictator, assuming the title Caudillo. This period in Spanish history, from the Nationalist victory to Franco's death, is commonly known as Francoist Spain or as the Francoist dictatorship.