Remilitarisation of the Rhineland - Wikipedia
The remilitarisation of the Rhineland (German: Rheinlandbesetzung, pronounced [ˈʁaɪnlantˌbəˈzɛtsʊŋ]) began on 7 March 1936, when military forces of Nazi Germany entered the Rhineland, which directly contravened the Treaty of Versailles and the Locarno Treaties. Neither France nor Britain was prepared for a military response, so they did not act.