Theatre of Zagłębie. In 1914, the village of Środula was incorporated into Sosnowiec. Poland finally regained independence in 1918, after World War I. In the Second Polish Republic, Sosnowiec became part of the Kielce Voivodeship, and in 1934 the City County of Sosnowiec was established. Sosnowiec suffered war damages during both major military conflicts in the 20th century: World War I, which caused mainly destruction to industry, and World War II, which brought about the terror of executions. World War II After the 1939 Invasion of Poland, which started World War II, the city was occupied by Nazi Germany and renamed Sosnowitz. On September 4, 1939, German troops murdered 10 Poles, including 15-year-old boy Henryk Słomka, in Sosnowiec in revenge for Polish defense. Around the same time, the Germans murdered nine Poles in nearby Klimontów (present-day district of Sosnowiec). The Einsatzgruppe zbV entered the city on September 12, 1939. The German police carried out mass searches of Polish houses. Initially under military administration set up as part of the General Government, Sosnowiec was annexed by Germany and incorporated into the Province of Silesia on 20 November 1939. In March 1940, the Germans established a transit camp (Gefangenensammellager) for arrested Poles in Sosnowiec. Inhabitants of Sosnowiec were also among Poles murdered in Celiny in June 1940. The Germans operated three labour subcamps of the Stalag VIII-B/344 prisoner-of-war camp in the city, and two more in the present-day district of Klimontów. The Polish underground resistance movement was active in the city. In June 1943 thousands of Jews were deported from Sosnowiec Ghetto to the Auschwitz concentration camp. The ghetto was liquidated two months later and almost all remaining Jews (around 15,000) were also deported to Auschwitz. Previously there had been considerable underground activity among them. The Germans established and operated two subcamps of the Auschwitz concentration camp in the city. In the first subcamp they held about 100 Polish forced labourers, and in the second, larger, they held hundreds of forced labourers, initially mostly Jews. In 1944, the Germans sent kidnapped Polish children from Sosnowiec to the Potulice concentration camp. The Vistula–Oder Offensive of the Red Army in January 1945 brought about the liberation of the city. Post-war After World War II, Sosnowiec further developed. On June 1, 1975, the metropolitan area was expanded when the neighbouring locations of Zagórze, Kazimierz Górniczy, Porąbka, Klimontów, and Maczki, became its districts. By 1977 the