Austrians
Historically, Austrians were regarded as ethnic Germans and viewed themselves as such. Austria was part of the Holy Roman Empire and the German Confederation until the Austro-Prussian war in 1866 which resulted in Prussia expelling Austria from the Confederation. Thus, when Germany was founded as a nation-state in 1871, Austria was not a part of it. In 1867, Austria was reformed into the Austro-Hungarian Empire. After the collapse of the Austro-Hungarian Empire in 1918 at the end of World War I, Austria was reduced to a rump state and adopted and briefly used the name the Republic of German-Austria ("Republik Deutschösterreich") in an attempt for union with the Republic of Germany, but was forbidden due to the Treaty of Saint-Germain-en-Laye (1919). The First Austrian Republic was founded in 1919. The Third Reich annexed Austria with the "Anschluss" in 1938.
Austria under National Socialism
SDAP, GVP, and DNSAP were clearly, although for different reasons, in favour a union of German Austria with the German state, which was also a republic by that time (Weimar Republic). The CS also tended to favour the union, but differed at first on a different subject - they were split on the idea of continuing the monarchy instead of a republic. Whereas only the KPÖ decidedly spoke against the annexation in the course of the 1920s and 1930s, the monarchists originally spoke up against the annexation and later turned to favor it, after the Bavarian Soviet Republic had failed, and Germany had a conservative government. The Treaty of Saint-Germain, signed 10 September 1919 by Karl Renner (SDAP), first chancellor of the republic, clearly forbade any union with Germany, abolished the monarchy, and clearly stated the First Austrian Republic as an independent country.