In 1945, with the approaching Red Army, a significant number of residents were either evacuated or fled the city at their own discretion. Following the Yalta Conference, Gliwice, along most of Silesia, was incorporated into communist Poland, and the remaining German population was expelled. Ethnic Poles, some of them themselves expelled from the Polish Kresy (which were incorporated into Soviet Union), started to settle down in Gliwice. Population estimates reached their pre-war levels in 1950, at 119,968 people. Gliwice's population peaked in 1988 at 223,403 inhabitants.