It began, after a couple of small-scale trials in August 1941, with the first experiment in mass killing conducted in the basement of Block 11 in the main camp the following month: 250 sick Polish inmates from the infirmary, some 600 Soviet prisoners of war and ten others were gassed on 4 September 1941. The killing worked well enough, but the location was not quite right. To reach the basement, there was a labyrinth of corridors to negotiate, which made removing the corpses and airing out the block cumbersome. Besides, it was not discreet enough . Block 11 was inside the camp perimeter; there were prisoners around. Happily for Auschwitz’s rulers, there was an alternative location, tucked out of view.
It was known initially as the ‘old crematorium’， later designated Crematorium I. They had been burning corpses there since August 1940, but after the test run at Block 11 the SS decided on a change of use for the biggest room in the building. Until then, this long, windowless room had served as a morgue : fifty-five feet long, fifteen feet wide and nine feet high. But now the morgue was to be repurposed into a gas chamber. That meant insulating the doors, and creating several openings in the ceiling through which pellets of Zyklon B might be dropped. The room could easily fit between 700 and 800 people, a thousand at a squeeze. Once again, Soviet prisoners were the guinea pigs. Ordered to undress in an anteroom, they thought they were entering the mortuary for delousing. They filed in quietly, though when the granules of Zyklon B were shaken down through the hole in the roof and exposed to the air below there were cries of ‘Gas!’ and a great bellowing sound as the trapped prisoners hurled themselves against both doors.
Before long, the gas chamber was ready for Jews. Those chosen to die would be brought to the doors of the crematorium on trucks or, if they had been taken to Auschwitz in freight trains, they might make this last leg of the voyage on foot, marched there in orderly fashion, five abreast. When the group was mostly made up of the elderly, they would walk slowly, their faces worn by the journey that had brought them there, and by all that they had endured up to that moment. The yellow stars looked large on their tatty clothes .
The SS men seemed to be unarmed, though in fact they had pistols hidden in their pockets. They would offer words of encouragement and reassurance, telling the Jews that they would soon be allocated work suitable to their trade or profession. Then the two SS men in charge would stand on the roof of the crematorium, to address the Jews gathered below. One of them was Maximilian Grabner, chief of the Politische Abteilung, the Political Department, tasked with the killing. He spoke in a voice that was warm, even friendly.
‘You will now bathe and be disinfected. We don’t want any epidemics in the camp. Then you will be brought to your barracks, where you’ll get some hot soup. You will be employed in accordance with your professional qualifications. Now undress and put your clothes in front of you on the ground.’
The captives were exhausted; they were desperate to believe their ordeal might be at an end. So they stepped forward, entering the one-time mortuary, children clinging to their mothers and fathers. Some were unnerved by the smell, the strong odour of cleaning products, perhaps bleach. Others looked for water pipes or shower heads in the ceiling, and could see none. A tremor of dread pulsed through the mass that was packed into this hall, and which was still growing. More and more people shoved themselves into the space. And yet the SS men were still there, still among them, ushering them forward, engaging in small talk, cracking the odd joke. Few noticed that these same SS men, smiling and friendly, were keeping a sharp eye on the exit, waiting for their cue.
It came when the last Jew had come in and the room was declared full, at which point the Nazis slipped out. Instantly the door was closed, a door trimmed with rubber that sealed it airtight. Then the sound of a heavy bolt, drawn securely into place.
Now the tremor turned into a wave of the deepest terror; it rippled through those locked inside. Some started banging on the door, demanding to be let out. They hammered with their fists. This time their SS guards offered no word of reassurance. Some of the men laughed. Others taunted their captives: ‘Don’t get burned while you have your bath!’
Those who were not looking at the sealed doors were instead gazing upward, noticing that the covers had been removed from the six holes in the ceiling. Perhaps the most terrifying sight was that of a head in a gas mask at one of the openings; it prompted a howl from those who saw it.
The head belonged to one of the ‘disinfectors’ who with chisel and hammer opened the tins whose labels announced: ‘Poison Gas! Zyklon.’ The cans were full of blue granules, each one no bigger than a pea. It was hydrogen cyanide in solid form; it had only to be exposed to the air for the prussic acid to escape from the pellets and transform into deadly gas. The disinfectors did not risk inhaling any fumes themselves. The instant the tin was open, they poured the crystals down the holes. Once the tin was empty, they covered the vent back up – though one SS man once saw a colleague briefly lift the covering and spit into the hall on those below, to add insult to lethal injury.
Grabner would watch carefully. Once he was satisfied that the Zyklon had been dispensed, he signalled to the driver of a truck, who had parked close by for this exact purpose, to start up his engine. His job was to make enough noise to drown out the cries and screams of the young and the old that would otherwise have filled the sky.
Grabner’s eye would stay fixed on the second hand of his watch. He was counting the two minutes it usually took for that animal sound of howling, the desperate weeping and praying, the violent banging and knocking to give way to a pained groaning and finally, two further minutes later, silence.
Then the truck drove away; the guards stood down. The cleaning squad – the men of Kanada command – came for the piles of clothes that had been neatly arranged, just as the SS man had advised. Eventually, once the room was declared sufficiently ventilated to be free of gas, the prisoners of Special Command, the Sonderkommando , would go inside to remove the bodies. They tended to be bunched up by the door, the corpses closely packed where the murdered, in their last few moments, had tried to force their way out. The limbs were often intertwined with each other, a tangle of arms and legs that had grown rigid thanks to the gas and which testified to the final chaos and terror. The bodies seemed to be leaning on each other and their mouths, sometimes still foaming, were wide open – as if agape in shock.
That was how it was at the beginning, when the sole gas chamber in use was the improvised one in the Auschwitz main camp. But steadily things changed. As the camp expanded and stretched into Birkenau, it made sense to install gassing facilities there, on the spot, rather than to rely on a single gas chamber some distance away – one that was soon creaking under the strain of overuse. There was another calculation too. Even outside the perimeter, and despite the effort to conceal it, the activity at Crematorium I attracted attention. Too many were noticing what was happening. Even when the truck driver had his engine running, or a motorbike was doing laps of the area, to hide the noise, prisoners close by were able to hear the sound of the heavy coughing and retching as the gassing began; they could hear the screams, of the children especially. The solution was an isolated and empty farmhouse – its owners had been evicted – near the birch forest which gave Birkenau its name.