On July 17, 1936, civil war broke out in Spain. The social-democratic elected government was attacked by rebellious army elements, led by Francisco Franco militarily and Primo De Rivera politically. Calling themselves 'falangists', these ultra-conservative totalitarianists quickly allied themselves with the fascist regimes in Italy and Germany, who swiftly came to their aid with heavy weaponry. Despite the overwhelming popular support for the legal government, the fascist war machine managed to destroy the government in less than three years.
The League Of Nations, which was bound by its founding charter to uphold the legal, elected government, stood idly by doing nothing. This didn't stop hundreds of thousands of men from around the world volunteering for service, of necessity organized into units by the Soviet Union, the only country, together with Mexico, that would not allow fascism to conquer Spain.
The passive stance of Europe and America, particularly the notion that "we'd rather have a violent coup d'êtat by fascists than a legally elected left-wing regime" is perhaps the most important factor in explaining Hitler's decision to invade his neighboring countries in the last years of the decade.
In Holland, volunteers who went to Spain lost their citizenship. A few years later, in 1945, the same happened to volunteers for the Waffen SS. In the 1970s, all Dutch SS-soldiers (war criminals by definition, as membership of the SS constitutes a war crime) had their citizenship collectively restored. Volunteers to Spain had to wait another decade before they could *individually petition* for restoration of their citizenship.
At the time, at least three ministers for the Dutch Christian-Democrats, the main ruling party, were ex-members of the nazi-party and/or the SS.
Not Plutus but Apollo rules Parnassus