Please answer a question about the following article about Karl Popper:

The failure of democratic parties to prevent fascism from taking over Austrian politics in the 1920s and 1930s traumatised Popper. He suffered from the direct consequences of this failure, since events after the Anschluss, the annexation of Austria by the German Reich in 1938, forced him into permanent exile. His most important works in the field of social scienceThe Poverty of Historicism (1944) and The Open Society and Its Enemies (1945)were inspired by his reflection on the events of his time and represented, in a sense, a reaction to the prevalent totalitarian ideologies that then dominated Central European politics. His books defended democratic liberalism as a social and political philosophy. They also represented extensive critiques of the philosophical presuppositions underpinning all forms of totalitarianism.

What was the Anschluss?
the annexation of Austria by the German Reich