Given that he died a matter of months before the Spanish Civil War broke out, one wonders what Spengler would have made of that conflict; he at the very least must have noticed the waters becoming more turbulent in Spain.
I bring that up because more than a few, and not without reason, reckon that the Spanish Civil War is effectively a vision of what is to come in America and Europe.
As far as the shape of things is concerned, I certainly do agree the Spanish Civil War is fairly decent model for what the coming escalation of the wider social conflict across the West will look like. Not some relatively neatly divided territorial schism, but a messy struggle with poorly-defined front lines. Nevertheless, certain geographical centres of gravity will exist (e.g. the great metropoleis as concentrations of establishment presence). As indeed noted before, we really should imagine a mix-up of:
-- the Spanish Civil War (a right mess filled with ideologically motivated atrocities committed by both sides);
-- the American Civil War (a generally clearly defined sense of "us" versus "them");
-- Weimar Germany crossing over into Nazism (a degenerate system is torn down, but the process givs way to unrestrained and even sadistic revanchism that is bound to ecalate);
-- a side order of 1990s Yugoslavia (old grudges are very much alive, and many see the chaos as an opportunity to exact "justice"), and;
-- a bit of the Troubles (lots of paramilitary activity and irregular campaigns, again involving structural atrocities against civilian targets).
Oh, and obiously... this era of history began with the French Revolution, and its conclusion will mirror that. So any "Caesarist" faction, once triumphant, will almost certainly engage in something quite similar to the Reign of Terror. (A socio-politico-cultural "cleansing" process that will have shades of German concentration camps and Russian gulags, too, no doubt.) Well, look at
that. The "highlights" of modernity, right there. It's like a fucked-up greatest hits album of the whole fucked-up era!
...Now, did Sengler say much about it? Not that I know of! He had the more acute example of the Weimar Republic's immolation right in front of him. I theorise that Spengler would have seen Franco as too much of a conservative. (He was, after all, no fan of the Junkers in Germany either. His "Prussianism" was essentially reformist. Rather like Nazism, but more intellectual, and without the deranged genocidal nonsense. "
Third way authoritarianism, but done by sane people" might be the right one-line description.)
Arnold Toynbee did comment on the Spanish Civil War, and inevitably -- and correctly -- saw it as an expression of a wider conflict within Western civilisation. He asked whether this was even a civil war in the normal sense... or rather an international war, simply waged on Spanish territory. To ask the question is to answer it.