Cannisters of Zyklon B and gas mask

Since the autumn of 1941, Höss and his colleagues had been experimenting with the use of Zyklon B to kill Soviet POWs and the sick in the camp's crematorium, which stood near his office.

But it soon became clear to Commandant Höss that this was not an ideal location to commit mass murder. Józef Paczynski, a Polish political prisoner at Auschwitz, explains why:

Crematorium, Auschwitz

I went into the attic. I stood on a crate. I lifted a roof tile and I could see everything that was going on right there in front of me. They were very polite with those people, very polite. Undress, pack your things here, this here, that there... Then an SS man climbed onto the flat roof of the building. He put on a gas mask, opened a hatch, and dropped the crystals in.

When he did this—in spite of the fact that these walls were very thick— you could hear a great scream from within. This took place at lunchtime. In order to stifle the screaming, they had two motorcycles standing on the pavement near the crematorium, engines revved up as far as they could go...  Józef Paczynski, Polish political prisoner, Auschwitz

Within a short time, Höss and other SS members found the ideal location for a new make-shift gas chambers where people could be murdered in relatively secrecy.

Little Red House (graphic reconstruction)

In a remote field a few miles from Auschwitz I, a cottage stood that would come to be known as the Little Red House, or Bunker 1. The windows and doors of the cottage were bricked up and two new entrances built, making the structure into two separate gas chambers. A few weeks later the Nazis rebuilt another nearby cottage exactly the same way. They called this one the Little White House.

In late March 1942 Jews deported from Slovakia first arrived at the railhead in Birkenau, two miles distant from the new cottages with their gas chambers. Eva Votavov?, a Slovakian Jew who came on a later transport, remembers her arrival there.

Eva Votavová Slovakian Jewish prisoner, Auschwitz When they opened the train carriages and forced us out, they shouted at us immediately. They were screaming in German. They were SS men who were dealing with us. We had to stand in line. Men had to step out first, then women with children, and then old people. I looked at my father, here, and I saw a sad look on his face. This is my last memory of him.

The Slovakian Jews selected for death were herded past the Birkenau camp and towards the isolated cottages.