At six-week intervals in 1943, a truck dispatched from Auschwitz traveled to Dessau, Germany. It returned with hermetically sealed tin canisters of Zyklon B, the commercial name for the bluish hydrogen cyanide pellets that asphyxiated more than a million Jews in the Auschwitz killing center.

A powerful pesticide developed during World War I, Zyklon B was used to combat contagious disease by fumigating lice-infested buildings. At first it served those purposes at Auschwitz, where overcrowding, malnutrition, and poor sanitation made dysentery, typhoid fever, and especially typhus constant threats. By late summer 1941, however, the Nazis experimented with Zyklon B on Soviet POWs. They found that the compound's vaporizing pellets offered a particularly reliable and efficient way to advance the "Final Solution."

Two German companies--DEGESCH, a subsidiary of I.G. Farben, and Tesch and Stabenow Company--profited immensely by supplying Zyklon B to the SS. They even modified it for Auschwitz by removing the special odor that ordinarily warned people about their product's deadly presence.

In 1942 Auschwitz used 8.2 tons of Zyklon B. The tonnage for 1943 was 13.4. Most of it was poured through small rooftop openings into gas chambers packed with Jews. Once exposed to air, the pellets produced lethal gas. Minutes later, after panic-filled screams, the human victims were dead.
Photo: Yad Vashem / United States Holocaust Memorial Museum Photo Archive