Use in the Holocaust thumb|upright|Empty Zyklon B canisters found by the Allies at Auschwitz-Birkenau in 1945 In early 1942, the Nazis began using Zyklon B as the preferred killing tool in extermination camps during the Holocaust. They used it to murder roughly 1.1 million people in gas chambers at Auschwitz-Birkenau, Majdanek, and elsewhere. Zyklon B was preferred because it was assumed to be a "humane" killing method, with the Nazis priding themselves as "civilized killers". Most of the victims were Jews, and by far the majority of murders using this method took place at Auschwitz. Distributor Heli supplied Zyklon B to Mauthausen, Dachau, and Buchenwald, and Testa supplied it to Auschwitz and Majdanek; camps also occasionally bought it directly from the manufacturers. Some 56 tonnes of the 729 tonnes sold in Germany in 1942–44 were sold to concentration camps, amounting to about 8 percent of domestic sales. Auschwitz received 23.8 tonnes, of which 6 tonnes were used for fumigation. The remainder was used in the gas chambers or lost to spoilage (the product had a stated shelf life of only three months). Testa conducted fumigations for the Wehrmacht and supplied them with Zyklon B. They also offered courses to the SS in the safe handling and use of the material for fumigation purposes. In April 1941, the German agriculture and interior ministries designated the SS as an authorized applier of the chemical, which meant they were able to use it without any further training or governmental oversight.
Use in the Holocaust thumb|upright|Empty Zyklon B canisters found by the Allies at Auschwitz-Birkenau in 1945 In early 1942, the Nazis began using Zyklon B as the preferred killing tool in extermination camps during the Holocaust. They used it to murder roughly 1.1 million people in gas chambers at Auschwitz-Birkenau, Majdanek, and elsewhere. Zyklon B was preferred because it was assumed to be a "humane" killing method, with the Nazis priding themselves as "civilized killers". Most of the victims were Jews, and by far the majority of m,urders using this method took place at Auschwitz. Distributor Heli supplied Zyklon B to Mauthausen, Dachau, and Buchenwald, and Testa supplied it to Auschwitz and Majdanek; camps also occasionally bought it directly from the manufacturers. Some 56 tonnes of the 729 tonnes sold in Germany in 1942–44 were sold to concentration camps, amounting to about 8 percent of domestic sales. Auschwitz received 23.8 tonnes, of which 6 tonnes were used for fumigation. The remainder was used in the gas chambers or lost to spoilage (the product had a stated shelf life of only three months). Testa conducted fumigations for the Wehrmacht and supplied them with Zyklon B. They also offered courses to the SS in the safe handling and use of the material for fumigation purposes. In April 1941 the German agriculture and interior ministries designated the SS as an authorized applier of the chemical, which meant they were able to use it without any further training or governmental oversight.