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 was the most significant cause of World War II, its occupation of most of Europe during the war, its disastrous invasion of the Soviet Union, and its commission of large-scale crimes against humanity, such as the persecution and mass-murder of Jews (the genocide known as the Holocaust), millions of Slavs, Romani and others. 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.
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The name Third Reich (Drittes Reich, ‘Third Empire’) invoked a historical reference to the Holy Roman Empire of the Middle Ages and the German Empire, 1871–1918.