Peninsula War (1808–1813, known in Spain as the Independence War). Despite the restoration of the previous order with the 1815 Congress of Vienna, the "nationalities question" became the main problem of Europe during the Industrial Era, leading in particular to the 1848 Revolutions, the Italian unification completed during the 1871 Franco-Prussian War, which itself culminated in the proclamation of the German Empire in the Hall of Mirrors in the Palace of Versailles, thus achieving the German unification. Meanwhile, the Ottoman Empire, the "sick man of Europe", was confronted with endless nationalist movements, which, along with the dissolving of the Austrian-Hungarian Empire, would lead to the creation, after World War I, of the various nation-states of the Balkans, with "national minorities" in their borders. Ethnic nationalism, which advocated the belief in a hereditary membership of the nation, made its appearance in the historical context surrounding the creation of the modern nation-states. One of its main influences was the Romantic nationalist movement at the turn of the 19th century, represented by figures such as Johann Herder (1744–1803), Johan Fichte (1762–1814) in the Addresses to the German Nation (1808), Friedrich Hegel (1770–1831), or also, in France, Jules Michelet (1798–1874). It was opposed to liberal nationalism, represented by authors such as Ernest Renan (1823–1892), who conceived of the nation as a community, which, instead of being based on the Volk ethnic group and on a specific, common language, was founded on the subjective will to live together ("the nation is a daily plebiscite", 1882) or also John Stuart Mill (1806–1873). Ethnic nationalism blended with scientific racist discourses, as well as with "continental imperialist" (Hannah Arendt, 1951) discourses, for example in the pan-Germanism discourses, which postulated the racial superiority of the German Volk (people/folk). The Pan-German League (Alldeutscher Verband), created in 1891, promoted German imperialism and "racial hygiene", and was opposed to intermarriage with Jews. Another popular current, the Völkisch movement, was also an important proponent of the German ethnic nationalist discourse, and it combined Pan-Germanism with modern racial antisemitism. Members of the Völkisch movement, in particular the Thule Society, would participate in the founding of the German Workers' Party (DAP) in Munich in 1918, the predecessor of the Nazi Party. Pan-Germanism played a decisive role in the interwar period of the 1920s–1930s. These currents began to associate the idea of the nation with the biological concept of a "master race" (often the "Aryan race"