What did the prisoners never realize or come to know about Auschwitz

That there were gas chambers in the camp itself.

Explanation:

By the time Soviet troops landed on its soil, on January 27, 1945, 1.1 million people were killed in Auschwitz, mostly Jews. In May 1940, Auschwitz became the place where political prisoners were imprisoned. As the war continued and the Holocaust spread, the Nazi regime further developed the camp. Auschwitz is actually a complex of as many as 40 concentration and destruction camps. The main camp is Auschwitz I, not far from Krakow, then Auschwitz II-Birkenau, three kilometers from the first, and Auschwitz III, a forced labor camp with numerous factories where inmates worked.