OT:...
3) Belgian Revolution. When the belgians declared independence from the netherlands the "congress system" failed to act because both France and Britain pursued there very own interests in this case. The belgian revolution demonstrated, that revolution and nationalsim are tolerated by the great powers. Thus the belgian revolution truly lit the fuse.
Sorry for the OT
Did it, though? The Belgian Revolution isn't nationalist as the term is commonly understood in the era (ethno-linguistic). The Belgians were Francophones and Flemish Francophiles (the latter is ironic, I realize), bound together by religion, certain political sensibilities, and common history under lapsed political boundaries.