Nazi Germany made increasingly aggressive territorial demands, threatening war if they were not met. It seized Austria and Czechoslovakia in 1938 and 1939. Hitler made a pact with Joseph Stalin and invaded Poland in September 1939, launching World War II in Europe.In alliance with Italy and smaller Axis powers, Germany conquered most of Europe by 1940 and threatened Great Britain.he official name of the state was the Deutsches Reich (German Reich) from 1933 to 1943 and Grossdeutsches Großdeutsches (Reich Greater German) reich from 1943 to. 1945 Nazi germany ceased to exist after The Allied forces Defeated germany In may, 1945 Ending World WAR ii In. europe