Lebensraum is a German concept of expansionism and Völkisch nationalism, the philosophy and policies of which were common to German politics from the 1890s to the 1940s. First popularized around 1901, Lebensraum became a geopolitical goal of the German Empire in World War I (1914–1918), as the core element of the Septemberprogramm of territorial expansion. The most extreme form of this ideology was promoted and initiated by the Nazi Party, that had ruled Nazi Germany, whose ultimate goal of which was to establish a Greater German Reich. Lebensraum was a leading motivation of Nazi Germany to initiate World War II, and it would continue this policy until the end of the conflict.