In a period of three months beginning on 28 April 1947 and with Soviet approval and aid , about 141,000 civilians residing around Bieszczady and Low Beskids were forcibly resettled to formerly German territories , ceded to Poland at the Yalta Conference at the end of World War II . The operation was named after the Vistula River , '' Wisła '' in Polish . Some Polish and Ukrainian politicians as well as historians condemned the operation following the 1989 fall of communism in Eastern Europe , and described it as ethnic cleansing . Others pointed out that no other means of stopping the violence existed at the time since partisans used to regroup outside the Polish borders
Yalta Conference
Yalta Conference
Operation Vistula