Gas chambers are BS. No doubt a concentration camp is fucking horrible, and punishment camps were real and ghastly, but the gas chamber stories where 'zyklon b' was presumably used are propaganda.

Brits started the stories initially as propaganda to bolster resistance efforts.

Red cross and US war crimes investigations proved it was BS, but Nuremberg trial outcomes relies on it being true (They coerced confessions through torture, leading to post war payout schemes assumedly). (GER pays reparations over $1B>Yr to this day).