Pan-Germanism (German: Pangermanismus or Alldeutsche Bewegung), also occasionally known as Pan-Germanicism, is a pan-nationalist political idea. Pan-Germanism seeks to unify all ethnic Germans, German-speaking people, and possibly also non-German Germanic peoples – into a single nation-state known as Greater Germany.
Pan-Germanism was highly influential in German politics in the 19th century during the unification of Germany when the German Empire was proclaimed as a nation-state in 1871 but without Germanophone Switzerland, Austria-Hungary, Luxembourg and Liechtenstein (Kleindeutsche Lösung/Lesser Germany) and the first half of the 20th century in Austria-Hungary and the German Empire. From the late 19th century, many Pan-Germanist thinkers, since 1891 organized in the Pan-German League, had adopted openly ethnocentric and racist ideologies, and ultimately gave rise to the foreign policy Heim ins Reich pursued by Nazi Germany under Adolf Hitler from 1938, one of the primary factors leading to the outbreak of World War II. The concept of a Greater Germany was attempted to be put into practice as the Greater Germanic Reich (German: Großgermanisches Reich), fully styled the Greater Germanic Reich of the German Nation (German: Großgermanisches Reich der Deutschen Nation). As a result of the Second World War, there was a clear backlash against Pan-Germanism and other related ideologies. Today, pan-Germanism is mainly limited to a few nationalist groups, mainly on the political right in Germany and Austria.