Between 1921 and 1925 Adolf Hitler developed the belief that Germany required Lebensraum ('living space') in order to survive. The conviction that this living space could be gained only in the east, and specifically from Russia, formed the core of this idea, and shaped his policy after his take-over of power in Germany in 1933.
It would be difficult and near impossible to see this as a single phenomenon and for it not to be seen as part of a broader process of colonization and imperialism at the time. However, one distinct feature of the colonies in North America was that there was massive migration of Europeans to these colonies whereas in other colonies at the time the migration was not as substantial.
To bring about a balance of power in Europe and prevent further conflict, they developed what became known as the Concert of Europe, beginning with the Congress of Vienna. The Congress of Vienna dissolved the Napoleonic world and attempted to restore the monarchies Napoleon had overthrown.
