Geoff Walden


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Birkenau (Auschwitz) Concentration and Extermination Camp

Part 2 - Selection, Gas Chambers, Crematoria


   Gas chambers were initially used at Birkenau to kill prisoners beginning in the spring of 1942. Two farm buildings on the outskirts of the camp were converted for use as gas chambers, before the construction of four dual-purpose gas chamber buildings with crematoria. These first two gas chambers in converted buildings were called Bunker 1 and Bunker 2, or the "Little Red House" and "Little White House," and were in operation from around March 1942 until spring 1943 (and possibly used again in May 1944). The bodies of the gassed prisoners were first buried nearby, then burned in special fire pits.

   Arriving transports of Jews, Gypsies, and other prisoners first went through a selection process on the arrival ramp, in which SS personnel and prisoner helpers separated the arrivals by gender (children staying with the women), and then lined them up for SS doctors to inspect. The SS doctors determined through a short visual examination who was fit for work, and would thus be admitted to the camp, and who would go immediately to the gas chambers (older people, children, women with babies, people with disabilities, etc.). From the spring of 1942 until May 1944, this selection process took place on the Judenrampe, with those designated for the gas chambers generally being driven there in trucks, while those fit for work either walked to the camp or were trucked. When the rail spur into Birkenau was finished in May 1944, the selection process took place inside the camp.

   In July 1942 the first Birkenau Sonderkommando (Special Squad) was formed of Jewish prisoners, whose duties were to bury corpses killed at Bunker 1 and Bunker 2. The first Sonderkommando was housed in Barracks 2 of Lager BIb, isolated from other prisoner barracks. Later they were moved to Barracks 13 of Lager BIId. Eventually, there were Sonderkommando for each crematorium, and they lived in the crematorium buildings where they worked. The Sonderkommando were forced to help keep order while the prisoners were disrobing and passing into the gas chambers, then pulling the bodies out of the gas chambers and cutting the women's hair and searching the corpses for hidden valuables, then loading the bodies into the crematoria ovens. The Sonderkommando operated the ovens and emptied the ashes. The Sonderkommando workers were periodically executed, since they were intimately familiar with the killing process, and few survived the end of World War II.

   Finding the capacity of the corpse burning pits around Bunkers 1 and 2 to be insufficient for the numbers of arriving prisoners, much larger crematoria were planned in 1942, initially based on plans for an additional crematorium that was to be built in the Auschwitz I main camp. The design for Crematorium II and Crematorium III was therefore for buildings with underground morgues and aboveground incinerators. Before they were built, the designs were changed to modify one of the morgue rooms into a gas chamber and the other into an undressing room. Two smaller facilities, Crematoria IV and V, were designed from the beginning to have integral gas chambers. (For details, see especially Ref. 3 throughout.)

   The main differences between Crematoria II/III and IV/V were the underground rooms of II/III (Crematoria IV/V were built entirely aboveground), the ventilation systems and method of Zyklon B introduction for the gas chambers, the smaller double chimneys of IV/V in contrast with the single large chimneys of II/III, and the differences in incineration capacities due to the number and configuration of the ovens. Crematoria II and III each had five triple-muffle ovens, for fifteen total burning chambers, and a planned combined capacity of 2,880 bodies in 24 hours. Crematoria IV/V each had four double-muffle ovens, with eight burning chambers, and a planned daily combined capacity of 1,536 bodies; thus a daily total for all four crematoria of over 4,400 bodies. (Ref. 3, page 342; Ref. 4, page. 429) These totals could be exceeded by loading more bodies, but the resulting heat often damaged the ovens and chimneys, putting some of the buildings out of service for various periods. In the summer of 1944, during the murder of the large shipments of Jews from Hungary, the crematoria could not keep up and burning pits were again used to dispose of corpses.

   Crematorium II, the first to be completed, was initially put into operation for a test firing on 5 March 1943. The gas chamber and crematorium were first used to kill and incinerate prisoners on 13 March 1943. Crematorium IV was completed second, on 22 March 1943, followed by Crematorium V on 4 April 1943, then Crematorium III on 25 June 1943. The Sonderkommando of Crematorium II participated in the revolt of 7 October 1944 (see here). But a year before that, on 23 October 1943, a group of Jewish women who were being led to the gas chamber of Crematorium II revolted against the SS guards. One of the women grabbed a pistol and shot two SS guards, one fatally. The other women attacked the guards with their bare hands, teeth, and fingernails. SS reinforcements restored order, shooting some of the women and forcing the rest into the gas chamber (see Ref. 4, page 513).

   The chemical agent used to murder prisoners in the gas chambers was Zyklon B, a cyanide-based insecticide produced by the DEGESCH company (Deutsche Gesellschaft für Schädlingsbekämpfung - German Corporation for Pest Control), partly owned by IG Farben. "Zyklon" ("Cyclone") was the company's name for the product, and the "B" stood for Blausäure, or prussic acid (hydrogen cyanide). The product had been in use for years in its intended function as a pesticide for clothing, bedding, and living areas, but after testing on prisoners in the Auschwitz I main camp in late summer 1941, it was adapted for use in the gas chambers. The product was shipped in sealed cans containing granules of an absorbent material which had been soaked in hydrogen cyanide. When introduced into the open air of the gas chambers, the hydrogen cyanide was released in gaseous form.

   The building designations in parentheses in the text (e.g., BW12f) were the original construction project numbers for each building.


These period photos are part of a group photographed by SS photographers and found at the end of the war, showing the selection process of a group of Hungarian Jews on the Birkenau ramp in June 1944. In these photos, the deportees are detraining and preparing to leave their belongings on the ramp, under the direction of SS guards and prisoner helpers. The building seen to the left is the Blockführer building (BW12f) for Lager BI. The buildings and chimneys of Crematoria II and III, the final destination for many of these people, can be seen in the distance.  (Yad Vashem Collections)


The same selection process, looking back toward the camp entrance. In the photo on the left the prisoners have been sorted by gender and lined up, and the SS doctors are preparing to start the selection, which is in process in the view on the right. The woman carrying a baby has been sent "to the left," which generally was the way to the gas chambers.  (Yad Vashem Collections)


As the selection process continues, groups are sent to the left, then turning to the right and past the Blockführer building, toward the gas chambers of Crematoria II and III.  (Yad Vashem Collections)


The wooden Blockführer building (BW12f), photographed on the left from an adjacent guard tower on a snowy day, survives along the rail line in Birkenau today.  (Yad Vashem Collections)


Crematorium II (BW30) appears on the left (with sewage treatment ponds in the foreground), with Crematorium III (BW30a) on the right above. Each of these crematoria had five triple-muffle ovens, which could cremate as many as five or more bodies in each muffle (at maximum capacity), for a daily total of some 1,440 incinerations in each crematorium (Ref. 3, page 342).  (Yad Vashem and Auschwitz-Birkenau Museum Collections,


As the front lines approached, Crematoria II and III were dismantled in November-December 1944, with the ovens and gassing apparatus being removed for transport to other camps closer to Germany. Just before the Soviet army arrived, these buildings were blown up on 20 January 1945. The ruins remain today - above is the chimney wing of Crematorium II. The oven area is seen in the lower right photo.


The ruins above are part of the roof of the eastern wing of Crematorium II, where the Sonderkommando lived in the attic (coke storage was on the ground floor in this wing). On the left below is a view looking down the stairs into the now unroofed underground disrobing chamber. The prisoners moved from there into the underground gas chamber, whose collapsed roof is seen on the right below.


Crematorium II nearing completion early in 1943.  (Yad Vashem Collections)


These photos show similar views of the ruins of Crematorium III, with its disrobing chamber below, and the gas chamber ruins at the bottom.


An international memorial to the dead of Auschwitz was erected in 1967 at the end of the Birkenau rail line, between the ruins of Crematoria II and III. Below are original cans of the Zyklon B insecticide that was used in the gas chambers to produce cyanide gas, on display in the Auschwitz Museum.


Crematorium IV (BW30b) during construction above, and finished below. Crematoria IV and V were smaller structures than Crematoria II and III, each with only two ovens having four muffles each, but two chimneys. The gas chambers were above ground, in the lower end wings. Crematorium IV was the scene of one of the most dramatic days at Birkenau - a revolt of the Sonderkommando on 7 October 1944. An uprising was being planned by the resistance movement, but it began early when the Sonderkommando received intelligence that they were all to be killed. The Sonderkommando of Crematorium IV attacked the SS guards with tools and stones and set the crematorium building on fire. The Sonderkommando of Crematorium II killed two SS men and a Kapo, two by pushing them into the burning ovens. The SS guard force reacted quickly to restore order, and most of the Sonderkommando in revolt were killed during the fighting or executed later. Crematorium IV was destroyed by the fire. 
Note that the brick parts of the walls of Crematorium IV that we see today were largely rebuilt after the war by the Auschwitz-Birkenau Museum (Ref. 3, pages 358, 387, 391).  (Auschwitz-Birkenau State Museum,


Crematorium V (BW30c) was the most isolated of the four main buildings, being surrounded by woods. After Crematorium IV was destroyed by fire and Crematoria II and III were dismantled, Crematorium V remained in use until the final days of the camp in January 1945. It was blown up by the SS on 26 January 1945, the day before liberation. Since the ovens were never removed, the ruins of Crematorium V still show ironwork frames of the oven assemblies. Similar to Crematorium IV, these brick walls were also reconstructed after the war by the Auschwitz-Birkenau Museum (Ref. 3, pages 358, 387; Ref. 4, page 802).  (Auschwitz-Birkenau State Museum,


Ashes from the crematoria and burning pits were scattered in various areas around Birkenau, including several ponds that are marked with memorials today. In addition to Birkenau, the ashes were scattered all over the Auschwitz area, including the banks of the Sola River, spread as fertilizer in fields, and even used as a base material for road and building construction.


Before the four large crematorium buildings were built, converted farm buildings called Bunker 1 and Bunker 2 (also called the "Little Red House" and "Little White House") were used as gas chambers (BW33). These buildings were located in isolated areas away from the main camp. Wooden disrobing sheds were located nearby, and the bodies were burned in adjacent burning pits (the bodies had first been buried, but later SS administration wanted these bodies dug up and burned). These Bunkers were in operation from March 1942 to April 1943, and Bunker 2 was likely put in use again in the spring of 1944 for the liquidation of the large transports of Hungarian Jews, when the arriving numbers were too many for Crematorium II-V to handle. The foundations of Bunker 2 are shown above, and the memorial on the site of Bunker 1 on the left below (no ruins of Bunker 1 remain). In common with Crematoria IV and V, these brick wall remains are said to have been rebuilt by the Auschwitz-Birkenau Museum. On the right below is a memorial located on the site of mass graves of Soviet Army prisoners who were murdered at Auschwitz.  (Google Maps link)


   Continue to Auschwitz III Monowitz and surrounding labor camps, along with the IG Farben Buna-Werke factory site
   Continue to Auschwitz "Interest Zone" - SS administrative buildings and housing, and factory, agricultural, and support sites outside the main camps
   Continue to Judenrampe rail arrival site
   Back to Auschwitz I Main Camp
   Back to Birkenau Part 1

Official Auschwitz-Birkenau Museum Webpage  --

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This page initially uploaded on 20 July 2000.