I do not know, Germany had more displaced people => after <= WWII than any other European countries and 500,000 died in the process [0].
Between 1944 and 1948 about 31 million people, were permanently or temporarily moved from Central and Eastern Europe.
The newly created UN even decided that a criteria for "migrant/displaced" person would exclude German people from the Poland/Hungary/etc...
[0] https://en.wikipedia.org/wiki/Flight_and_expulsion_of_German...