Anschluss
On this day in 1938, German troops entered Austria. At our comfortable distance here in the US, the Anschluß is most familiar to us in its musical form from The Sound of Music, where the impression is that the good Captain will not live under fascism.
The truth is that Austria was already fascist in 1938; it was only the flag with the spider on it (in musical terms) that changed. The issue was sovereignty, not freedom - nationalism, not Naziism. [The reader may insert the obvious comments about the EU here.] In musicals, at least, nationalism is still a virtue.