Nazi Germany and the Third Reich are the colloquial English names for Germany under the regime of Adolf Hitler and the National Socialist German Workers Party (NSDAP), which established a totalitarian dictatorship that existed from 1933 to 1945. Officially, the state was, as in the preceding Weimar Republic era, still called the Deutsches Reich (German Reich). In 1943, Großdeutsches Reich (Greater German Reich) became the official name.

The state was a major European power from the 1930s to the mid-1940s. Its historical significance lies mainly in its responsibility for escalating political tensions in Europe by its expansionist foreign policy which resulted in World War II, its occupation of most of Europe during the war, and its commission of large-scale crimes against humanity, such as the persecution and mass-murder of millions of Jews, minorities, and dissidents in the genocide known as the Holocaust. The state came to an end in 1945, after the Allied Powers succeeded in seizing German-occupied territories in Europe and in occupying Germany itself.[4]

In 1935, Germany was bounded on the north by the North Sea, Denmark, and the Baltic Sea; to the east by Lithuania, The Free City of Danzig, Poland and Czechoslovakia; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium, the Netherlands and the Saarland, which joined in 1935. These borders changed after the state annexed Austria, the Sudetenland, Bohemia and Moravia and Memel, and after subsequent expansion during World War II.

The name Third Reich (Drittes Reich, ‘Third Empire’) invoked a historical reference to the Holy Roman Empire of the Middle Ages and the German Empire, 1871–1918.