https://amgreatness.com/2022/04/24/our-spanish-civil-war/
From 1936 to 1939, the civil war in Spain became a European laboratory of new tactics, strategies, logistics, wartime morality, and weapons. Right-wing nationalists under General Francisco Franco finally defeated loyal supporters of an evolutionary socialist republic—but only after much of the Western world had variously weighed in.
The cost to the Spanish people of such brutal and vicious strife was horrific. Over 500,000 Spaniards would die in a little over two-and-a-half years. The country was left in shambles.
Dictatorships in Nazi Germany, fascist Italy, and autocratic Portugal poured millions of dollars in military aid and money for Franco’s efforts to seize power. In turn, the Soviet Union often matched that aid with shipments to various communists, socialists, and anarchists of the Popular Front forces.
Whether by design or by accident, Spain became a proving ground for many of the strategies, weapons, and tactics that would follow later in World War II. And it would be a preview of just how impotent democracies and international bodies were to stop aggressive powers.
The relatively new regime of Nazi Germany sent to Spain hundreds of tanks and “volunteer” troops, pilots, dive bombers, and transport planes of the Condor Legion.
But Germany’s intervention was not always quite what it seemed. Behind the scenes, Adolf Hitler provided enough aid to ensure Franco’s likely eventual victory. But he did not send quite enough immediate help either to antagonize his European democratic rivals, or to ensure a quick victory for the Nationalists that might have created a powerful and independent Iberian fascist rival bloc to his own.