During the First World War, the Allied naval blockade of the Central Powers caused food shortages in Germany and resources from Germany colonies in Africa were unable to slip past the blockade; this caused support to rise during the war for a that would expand Germany eastward into Russia to gain control of their resources to prevent such a situation from occurring in the future. In the period between the First and the Second World Wars, German nationalists adopted the term in their political demands for the re-establishment of the German colonial empire, which had been dismembered by the Allies at Versailles. Ratzel said that the development of a people into a society was primarily influenced by their geographic situation (habitat) and that a society that successfully adapted to one geographic territory would naturally and logically expand the boundaries of their nation into another territory. Yet, to resolve German overpopulation, Ratzel said that Imperial Germany (1871–1918) required overseas colonies to which surplus Germans ought to emigrate.