Wikipedia
Pan-Germanism or Pan-Germanicism (; see also Pan-Germanicism) is a pan-nationalist political idea. Pan-Germanists originally sought to unify all the German and possibly also Germanic-speaking peoples in a single nation-state known as Großdeutschland.
Pan-Germanism was highly influential in German politics in the 19th century during the unification of Germany when the German Empire was proclaimed in as a nation-state in 1871 without Austria (Kleindeutsche Lösung/Lesser Germany), and the first half of the 20th century in the Austro-Hungarian Empire 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. As a result of the disaster of World War II, Pan-Germanism was mostly seen as a taboo ideology in the postwar period in both West and East Germany. Today, Pan-Germanism is mostly limited to some nationalist groups in Germany and Austria.