The Ghetto, referred to as the "Jewish quarter" (or "Wohngebiet der Juden"), was formally opened a year later on 24 March 1941. The expulsion and ghettoization of the Jews was decided when the arriving Wehrmacht troops preparing for the Operation Barbarossa, the invasion of the Soviet Union, needed housing close to the new German–Soviet frontier. The ghetto, the only one so far in the Lublin District of the General Government in 1941, was located around the area of the Podzamcze district, from the Grodzka Gate (renamed "Jewish Gate" to mark the boundary between the Jewish and non-Jewish sections of the city) and then along Lubartowska and Unicka streets, to the end of the Franciszkańska Street. Selected members of the prewar political parties such as the Jewish Bund in Poland were imprisoned in the Lublin Castle and continued to carry out their underground activities from there.