Auschwitz (German: [ˈaʊ̯ʃvɪts]), also known as Oświęcim (Polish: [ɔˈɕfjɛɲ.t͡ɕim]), was a complex of over 40 concentration and extermination camps operated by Nazi Germany in occupied Poland (in a portion annexed into Germany in 1939) during World War II and the Holocaust. It consisted of Auschwitz I, the main camp (Stammlager) in Oświęcim; Auschwitz II-Birkenau, a concentration and extermination camp with gas chambers, Auschwitz III-Monowitz, a labour camp for the chemical conglomerate IG Farben, and dozens of subcamps. After Germany initiated World War II by invading Poland in September 1939, the Schutzstaffel (SS) converted Auschwitz I, an army barracks, into a prisoner-of-war camp.