Concentration camps were not only used by Nazi Germany but also the Soviet Union, though the Soviet camps were harder to find as they were located in Siberia. Concentration camps began during the Second Boer War in South Africa and became widely known after World War 2 when the scale of Nazi camps for Jews and political prisoners was revealed, including the first camp at Dachau in 1933. Gas chambers were used in concentration camps as an efficient way to kill large numbers of prisoners, who were forced to operate the gas themselves. Over 3.5 million people, including children and women, were imprisoned in camps between 1933-1945, where horrible medical experiments were performed on children. During World War 2 there were over 300 camps in Germany