 Representatives of the Polish government officially took over the civilian administration of the southern part of East Prussia on 23 May 1945.Subsequently, Polish expatriates from Polish lands annexed by the Soviet Union as well as Ukrainians and Lemkos from southern Poland, expelled in Operation Vistula in 1947, were settled in the area, now called Warmian-Masurian Voivodeship.In 1950 the Olsztyn Voivodeship counted 689,000 inhabitants, 22.6% of them coming from areas annexed by the Soviet Union, 10% Ukrainians, and 18.5% of them pre-war inhabitants.