[HideousKojima]

>But that didn't happen.

The latter part definitely did. See Konigsberg (now Kaliningrad, a Russian exclave) and all the parts of Germany that were ceded to Poland.

And the expulsion of ethnic Germans living in non-German lands across Europe postwar was certainly a form of ethnic cleansing, even if you believe it was justified to remove the justification Germany had for prewar annexations like the Sudetenland.