German troops entered Austria [the Anschluss] on March 12 1938, Hitler himself crossed into Austria on the same date. A Nazi government under Seyss-Inquart was established on March 13 1938, and it joined with Hitler in proclaiming the Anschluss [political union of Austria and Germany] On the following day Hitler [born in Austria] made his grand entry into Vienna, a city he had known well in earlier years.
On returning to Germany, Hitler ordered a plebiscite for the Austrians and Germans, they were asked to approve the Anschluss, on April 10 1938 the result was announced 99% voting in favour.
The Nazi occupation of Austria was soon marked by anti-Jewish violence, the likes of which had not even taken place in Germany. Vienna with around 180,000 Jews, was the scene of mass brutality, throughout the city, Jewish men and women were grabbed and forced to scrub the walls and side-walks, removing any pro-independence slogans, further humiliations took place such as cleaning public and SS toilets with sacred Hebrew prayer cloths, thousands were also jailed without reason, and the police allowed looting of Jewish homes and businesses.
SS leaders Himmler and Heydrich were quick to realise that Jews would pay large sums of money to exit the country. They set up an Office for Jewish emigration, which was run by the notorious SS man Adolf Eichmann, it extorted money and valuables from Jews in return for their freedom. Himmler also established the first concentration camp outside Germany at Mauthausen, near Linz, around 120,000 inmates would be worked to death there in the Granite quarry, others being shot on attempting to escape.
When WW2 began in September 1939, more than 100,000 Jews had left Austria, which was around half of all Austrian Jews. When the war ended in May 1945, more than 65,000 Austrian Jews had died, many of them in extermination camps, thousands of Roma gypsies were also murdered.
Austrians were overrepresented in the reign of terror against the Jews, but also on the battlefields, during the course of the war, hundred of thousands of Austrians fought under the Nazi banner. A substantial number served in the brutal SS. Austria [after the Anschluss] represented about 8% of the population of the Third Reich, yet about 13% of the SS, and around 40% of the concentration camp personnel [70% of those being in charge of the camps] were Austrians.