I think calling the EU a "Fourth Reich" and comparing it to Hitler or the old Roman Empire is a bad analogy. The EU is more like the old Holy Roman Empire of the Middle Ages, the "First Reich"... a cross between a confederation and a supranational government. it was not holy, it was not Roman, and it was not an empire. It was an amalgamation of separate nations that imploded upon itself.
Economically the EU may be strong but they have no military strength. They won't be able to hold the EU together through brute force. Plus the Eastern European countries & the UK aren't entirely going along with the idea of an EU common defense policy. If France and Germany think they can turn the EU into a superpower to rival the US they are mistaken.
The SS was a cross Europe army that had Germans, Austrians, Belgians, Czechs, Slovaks, Bulgarians, Romanians, Italians, French, Danes, Fins, Croatians, Albanians, Bosniaks, Slovanians, Greeks, Latvians, Lithuanians, Ukranians, Estonians and even some Britians. They did it once, they can do it again.