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.

The Soviet Union ostensibly countered fascist supply chains. But Joseph Stalin had even more strings attached to his aid. He systematically favored communist recipients and harassed and often eliminated their socialist and anarchist allies in the Popular Front.

Stranger still, even before the Soviet-Nazi nonaggression pact of 1939, Hitler and Stalin were already secretly aiding each other’s rearmament in their shared hatred of Western European democracies. It would take years of research to fathom all of the subtexts and agendas behind the great powers’ interventions in the Spanish Civil war.

The same labyrinth of plots and twists will likely prove true in the present Ukrainian war. Ostensibly NATO and the EU are staunch Ukrainian allies. But powerful German interests remain worried about their tenuous energy supply lines from Russia and are not so ready to cut off all trade with Putin.

China seems all in as a Russian benefactor. But it is sending mixed diplomatic signals as it weighs lucrative gas and oil deals with an increasingly isolated Putin against endangering its profitable mercantile trading with the West. Before the war, plenty of Ukrainians from its majority Russian-speaking borderlands were playing both sides during the ongoing turmoil. As with the Spanish Civil War, Ukraine ostensibly is a war between elected governments and autocracies–but with deal-making and intrigue on both sides.

The relatively young League of Nations never could broker peace in Spain. It had earlier failed in Manchuria to stop Japanese aggression, and it never stopped the brutal Italian occupation of Ethiopia. So by 1936, the league remained mostly a shrill megaphone, without any power to stop either fascist or communist aggression.

Instead, ad hoc alliances sprung up during the war to enforce nonintervention among individual nations. But their declarations, sanctions, boycotts, and embargoes were likewise mostly soon bypassed by both Germany and the Soviet Union.

In other words, an anemic League was not all that much different from an impotent United Nations that has been utterly ineffective in offering any solution to Ukraine.

Similarly, the West may boast of its unprecedented tough sanctions against Russia. But in truth, governments that control the majority of the planet’s population—especially the nearly 3 billion people of China and India—are still trading freely with Russia to guarantee their own oil and gas supplies. In 1936 sanctions did not stop the immediate killing, and they likely will not either in 2022.

Franco was roundly condemned by the Western democracies and his supporters were sanctioned, but his efforts were not materially altered. That, too, may sound familiar when we compare the idealism of anti-Russian sanctions versus the reality of the considerable wherewithal at Putin’s disposal.

Spain soon became a romantic cause for international brigades. Idealist Westerners flocked to help the Republicans, while the Nationalists were often secretly sent “volunteers” from their fascist supporters. Yet, for all the idealist rhetoric, foreign fighters played a minor role in the war’s outcome.

Novelists like George Orwell (Homage to Catalina), Ernest Hemingway (For Whom the Bells Toll), and Muriel Spark (The Prime of Miss Jean Brodie) portrayed the misplaced idealism of the international brigades, the often-cynical use of them by their hosts and third-party nations, and the chaotic changing alliances within Spain itself.

In similar fashion, we hear sensationalized reports about Europeans and Americans pouring in to fight for Ukraine. Darker stories abound about Syrians, Chechens, and private mercenary killers that Vladimir Putin has hired or impressed. But more likely, as in the Spanish Civil War, such foreigners will play a relatively insignificant role in the outcome.

Political ideologies certainly had sparked European wars, from antiquity to the Napoleonic era. More often, however, conflicts were fought over disputed lands, religion, natural resources, race and ethnicity, nationalism, and competition for continental influence.

Germany’s Kaiser Wilhelm II was propagandized during World War I as an anti-democratic monster. But the war itself was not so much ideological as it was a great-power European rivalry, particularly over how to handle the rising “German problem.”

The Spanish Civil War was a different 20th-century ideological struggle for the future of the contours of Europe. Both the Popular and National Fronts symbolized growing extremism that the democracies were ill-equipped to contain.

Indeed, Western European democracies appeared weak in comparison to the zeal of communists, anarchists, and radical socialists, especially when empowered by the new communist Soviet superpower. Similarly, Franco saw Europe’s future more in line with the increasingly influential and often popular fascism of Hitler and Mussolini, albeit with his own Catholic monarchist twist. By 1936 leftist and rightist ideologues were battling in every Spanish town, as violence broke out even among families and friends.

Ukraine likewise is not just a Russian power grab as we saw in Ossetia and earlier in Eastern Ukrainian and Crimea. This time around, Russian propaganda has masked its war of aggression under the banner of Western traditionalism—autocracy, orthodox Christianity, conservative social mores, the preservation of traditions, the power of reactionary Mother Russia—versus the supposed “decadent” democracies.

The democracies see Putin as the new evil incarnation of fascism, whose bleak view of Europe’s future would mark a return to the dark days of the 1930s. Whether true or not, “freedom” and “democracy” versus “tyranny” and “fascism” are now the ostensible fault lines in Ukraine. These ideological catalysts are mostly unlike what drove recent conflicts of tribalism, religion, and ethnicity in the Middle East, the former Yugoslavia, or Rwanda.

Ukraine is also offering a supposed preview of what the next war will be, in the manner that novel close air support for armor thrusts occasionally characterized the Nazi role in Spain. By September 1939, those tactics were applied to Poland. Monoplanes bombing towns and blasting pathways for tanks replaced the trench warfare of World War I as Germany unleashed its now honed blitzkriegs throughout Europe.

Small, skilled Ukrainian teams with Javelin and Stinger missiles destroyed multimillion-dollar helicopters and armored vehicles. Cheap, armed drones are now ubiquitous on both sides. Do these relatively inexpensive arsenals presage a more decentralized brand of warfare, where handheld weapons take out relatively sophisticated tanks and helicopters? Are we back to the superiority of quantity over quality in weapons of war?

Perhaps, but whether armor and artillery prove vestigial weapons and tactics remains to be seen as the theater is now shifting to the rolling wide-open plains of Eastern Ukraine.

Before Ukraine—as before the Spanish Civil War—there were lingering Western pretensions that certain “rules of war” always formally exempted civilians. These assumptions supposedly precluded the deliberate slaughter of civilians or the bombing of residential centers into oblivion.

Often contemporary Western leaders talked of 19th- or 20th-century wartime values as passé in our more enlightened and evolved 21st century.

In World War I, the filth and disease of the trenches in Western Europe, in peripheral theaters in Italy, Russia, and the Middle East, had cost 20 million lives. But postwar utopians in the 1930s still believed that civilians had not been deliberately targeted in World War I, whose greatest percentage of dead remained largely soldiers.

Spain shattered such illusions. Both fascists and communists murdered innocents. They executed neutrals on the spot. The fascists bombed cities without strategic rationales. Picasso’s famous oil painting “Guernica” of the German bombing of a Basque town of mostly women and children became instantly emblematic of a novel form of 20th-century war. So the barbarity of the Spanish Civil War offered a glimpse of World War II to come when the vast majority of the 65 million dead would prove to be civilians.

Before Ukraine, few, if any, recent leaders of a major nuclear nation had ever seriously threatened to use nuclear weapons against either his enemies on the battlefield or those who sent help to them—not in Vietnam, not in Afghanistan, not in the wider Middle East. Now Vladimir Putin not only brags about his nuclear arsenal and tests long-range missiles but boasts about his right to use any weapon he chooses to defeat Ukraine and its suppliers.

Ukraine, like Spain, has awoken us from our false sense of security that has grown since the end of the Cold War. Unfortunately, soldiers in war sometimes do deliberately flatten apartment buildings and shoot civilians en masse—whether in 1936 or 2022. And some leaders apparently now view nuclear bombs as more or less deadlier conventional weapons.

Human nature is constant, despite radical changes in technology, social systems, and physical landscapes. That bleak reality should remind us that the veneer of civilization is always very thin, while the innate barbarity of humankind is forever very deep. We saw that in 1936-1939, and what followed from it in World War II. And now, in 2022, we have awakened again out of our complacency—with a deep foreboding of what will soon follow in war after Ukraine.