It's called "der Anschluss"
Prussia and Austria
austria
Vereinigung mit Österreich
Austria
Prussia and Austria were the two most powerful German states.
The unification of Germany Rebellions in Austria The unification of Italy Rebellions in Austria
He thinks that Austria would resist unification and weaken a unified Germany. -Apex
Germany first made a unification with Austria-Hungarian in 1879, later in 1882 Italy joined this unification. They were now alliances.
One obstacle to German unification was that Austria did not want a powerful neighbor. Religion was another obstacle, as well as individuals not wanting to lose their power.
Helmut Kohl
During the early nineteenth century, Prussia was the only German state that could match the power and influence of the Austrian Empire. They were comparable in terms of size, population and wealth. Austria opposed the idea of German unification as it saw this as a threat to its own empire. Although they were a minority, there was a significant percentage of German-speakers in the empire. If they broke away to join a unified Germany, Austria would be smaller and weaker. To this end, Prussia and Austria were rivals.
He thinks that Austria would resist unification and weaken a unified Germany.