Germany established its first democracy in 1919 with the creation of the Weimar Republic, a parliamentary republic created following the German Empire's defeat in World War I. The Weimar Republic lasted only 14 years before it collapsed and was replaced by Nazi dictatorship. Historians continue to debate the reasons why the Weimar Republic's attempt at democratization failed. After Germany was militarily defeated in World War II, democracy was reestablished in West Germany during the U.S.-led occupation which undertook the denazification of society.