Following World War I, and to an extent prior to then, a lot of Austrians, due to shared ethnolinguistic heritage, considered themselves Germans and felt as though Austria should join Germany. Hitler, due to his ultranationalist beliefs, was one of these Austrians.

At the beginning of WWI, Hitler joined the German army rather than fight for Austria-Hungary, which was a multinational empire that contained many Slavs and others who he considered to be subhuman. He identified with Germany from that point onwards. Later, Hitler convinced a pro-Nazi official in Austria to revolve his citizenship so that Weimar Germany could not simply expel him from the country.