On 2 April 1938 , 200,000 Austrians gathered on the Heldenplatz ( Square of Heroes ) to hear Hitler proclaim the Austrian Anschluss . Hitler 's travel through Austria became a triumphal tour that climaxed in Vienna , on 2 April 1938 , when around 200,000 Austrians gathered on the Heldenplatz ( Square of Heroes ) to hear Hitler proclaim the Austrian Anschluss .