Germanisation (also spelt Germanization) refers to the spread of the German language, people and culture or policies which introduced these changes. It was a central plank of German conservative thinking in the 19th and 20th centuries, at a period when conservatism and nationalism went hand-in-hand. In linguistics, Germanisation also occurs when a word from the German language is adopted into a foreign language.
Under the policies of states such as Prussia, Austria, the German Empire and Nazi Germany, non-Germans were often banned from use of their language, the state discriminated their traditions and culture, when those measures were not successful in eradicating non-Germans, colonists and settlers were used to upset the population balance. During the Nazi era, Germanisation turned into a policy of ethnic cleansing and later into genocide of non-Germans.
Historically, there are very different forms and degrees of the expansion of the German language and of elements of German culture. There are examples of complete assimilation into German culture, as happened with the pagan Slavs in the Diocese of Bamberg (Franconia) in the 11th century. A perfect example of eclectic adoption of German culture is the field of law in Imperial and present-day Japan, which is organised very much according to the model of the German Empire. Germanisation took place by cultural contact, by political decision of the adopting party (e.g., in the case of Japan), or (especially in the case of Imperial and Nazi Germany) by force.