Yugoslavia, interrupted: A European success story ruined by NATO invasion

I don’t know it was such a success story. There was a brutal civil war and prior to that, during WW II they fought against each other with Slavs like the Croatians taking up sides with Germany. The victorious allies of WW I created this situation when they broke up the Austro-Hungarian Empire. Things were largely peaceful for centuries under that great empires rule, not after it was broken up and Yugoslavia was created. Yugoslavia, like Czechoslovakia and like almost everything the allies did after WW I was a big failure, resulting in many things that would be regretted, including WW II.