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HolocaustMarch 1943

Murder factory at Birkenau

Combined crematorium and gas chamber complex, Auschwitz/Birkenau
Combined crematorium and gas chamber complex, Auschwitz/Birkenau

In March 1943 a combined crematorium and gas chamber complex opened at Auschwitz/Birkenau. This was an event of great significance. Because the building had a long and changeable history – one that helps us understand the evolution of Auschwitz’s capacity to murder.

The plan for a new crematorium dated back to October 1941, when the idea had been to replace the old crematorium in Auschwitz main camp. But then, during 1942, the function of this new building was changed by the SS architect, Walter Dejaco, and its location was shifted from the main camp to Auschwitz/Birkenau. The plan for the basement rooms, which had originally been designed as mortuaries, were now altered so that one mortuary became an undressing room, and the other, set at 90 degrees to the first, became a gas chamber. A careful study of the plans clearly reveals this change in function – the door to the gas chamber, for example, was re-set so that it opened outwards (a change made with the knowledge that the room would now be crammed with dead bodies after the gassing had taken place, making it impossible to open the door inwards, as originally planned). Plus, a ‘spy hole’ was to be set into this door – something that would be unnecessary if this was simply to be a door to a mortuary.     

In addition, there were a number of other small but significant changes in the design – like the replacement of a corpse chute with stairs (since large numbers of people would now need to be able to walk down into the basement of the building) – all of which point to the fact that this building was now designed to be a killing factory with the gas chamber below ground level and the crematorium ovens above. The plan was that canisters of Zyklon B insecticide would be inserted via hatches on the roof of the gas chamber and then the dead bodies taken up via a lift to be burnt in the ovens of the crematorium.

During 1942, at the same time as these design changes were being made to the original design of the crematorium, several more crematoria/gas chambers were ordered for Auschwitz/Birkenau. Indeed, by the summer of 1943 a total of four such complexes were in operation. Two of them (crematoria 2 and 3) followed the original modified design with the gas chambers in the old mortuary in the basement, and two more (crematoria 4 and 5) were new designs, with the gas chambers on the same level as the ovens of the crematoria. Each of these four buildings could murder around 4,700 people a day – which meant that by the summer of 1943 Auschwitz/Birkenau had a killing capacity of 150,000 people a month.

It’s important to remember that the journey to this extraordinary moment in the history of crime was not a straight one. Auschwitz main camp – about a mile and a half away from Auschwitz/Birkenau – had been opened in June 1940 as a concentration camp to hold Poles from the surrounding area who the Nazis thought a threat to their rule. The regime in the camp was appallingly brutal – around half of these original prisoners would be dead by 1942 – but the original Auschwitz was not conceived of as an extermination camp. It was the war against the Soviet Union, begun in June 1941, that acted as a catalyst for change. First Soviet political officers – commissars – were murdered in Auschwitz main camp by a combination of beatings, starvation and shooting. Then, in late August or early September, the first killing experiments were conducted with Zyklon B on Soviet POWs and sick Polish prisoners in the basement of Block 11 – the punishment block. Further killing experiments were then carried out in the existing crematorium in the main camp later that autumn.       

Meantime, also in the autumn of 1941, 10,000 Soviet POWs arrived to build a vast new camp at a village the Germans called Birkenau, a short distance away from Auschwitz main camp. Auschwitz/Birkenau was initially intended to hold around 100,000 POWs, but by early 1942 the Nazis had decided that the Soviet prisoners should be sent elsewhere as forced labour.

Auschwitz/Birkenau was now a camp without a purpose. But not for long, as the SS soon decided that this would be a suitable place to send the Jews. By the spring Slovakian Jews arrived – the first Jews from outside Poland. To begin with these Jews were all admitted to the camp, but soon the SS began the infamous ‘selections’ on arrival – with those thought not capable of work killed almost immediately. In order to murder the Jews the SS, starting in March 1942, improvised gas chambers in two peasant cottages (Bunkers 1 and 2 or the Little White House and the Little Red House) at a remote corner of Birkenau. But whilst the killing in the cottages went to plan for the SS, the disposal of the bodies did not. In the summer heat of 1942 the bodies – many lightly covered in earth – started to putrefy. Other Jewish prisoners were forced to dig these bodies up and burn them.

Meantime the so-called ‘Operation Reinhard’ death camps had begun their work elsewhere in Poland – places like Treblinka, Sobibor and Belzec. And these camps killed far more people in 1942 than Auschwitz. It was only once the new crematoria/gas chambers opened in 1943 that Auschwitz began to have a similar capacity to kill.    

Thus Auschwitz – which was to become the site of the largest mass murder in the history of the world – was relatively late in its development as a killing factory. Part of the reason was that Auschwitz was unique in that, by 1942, it offered three functions to the Nazis – concentration camp, forced labour camp (providing slave labour for many industrial concerns nearby) and death camp – whilst the Operation Reinhard camps had only one purpose: murder.

It was only in 1943 that the Nazis began to make full use of the multi-functions of Auschwitz – at this camp Jews would still die, but some could be worked to death over several months rather than killed on arrival. Auschwitz was also more secure than the remote Operation Reinhard camps – something that must have been clear to Himmler when, in the autumn of 1943, there were successful resistance break-outs at both Sobibor and Treblinka.

The crematoria/gas chambers that opened at Auschwitz/Birkenau in 1943 have become symbols of the horror of the Holocaust. Not just because of the scale of the killing that took place there, but because of their modernity. These solid brick-built buildings resembled modern factories – which isn’t surprising because, in a way, that’s what they were – factories of death. Places where murder could be conducted on an industrial scale.    

These crematoria also offer us an important insight into the minds of the perpetrators, because each building was operated by less than a dozen SS. Almost all the psychologically crippling tasks associated with the mass killing – like the burning of the bodies and the cleaning of the gas chambers – were performed by Auschwitz prisoners called the Sonderkommando who were forced to participate in the extermination process on pain of their own immediate death.

After witnessing the shooting of Jews on the Eastern Front in 1941, Himmler had sought a killing process which spared the mental anguish of his killers. At Auschwitz in 1943, the SS established buildings which did just that.


The photo of the combined crematorium/gas chamber complex is from the collection at Auschwitz Birkenau Memorial State Museum.