Anschluss

Annexation of the Federal State of Austria into Nazi Germany on 12 March 1938. The idea of uniting Austria and Germany arose after the 1871 unification excluded Austria, and it gained support after the Austro-Hungarian Empire fell in 1918; the 1919 Treaty of Saint-Germain and Treaty of Versailles forbade the union and stripped Austria of territories such as the Sudetenland.