I had Germany go the soft power rather than the hard power route. It's more stable.
Groß-Österreich is short for the United States of Greater Austria, a plan by Franz Ferdinand to reform the Austro-Hungarian Empire. While Franz himself is dead, parts of the reform plan went into action.
Germany and Austria naturally led the charge in the 1960s with various economic and political treaties, with the French and British being skeptical but joining decades later in the 1990s. Franco-German relations were worse than OTL's post-war era, but the French eventually got over it and have become one of the powerhouses of the EU.