The title of the poem “we will never forget auschwitz” is an allusion to

The title of the poem "We Will Never Forget Auschwitz" is an allusion to the experiences of  the Jews during the Holocaust.

Auschwitz was a network of German Nazi concentration camps and extermination camps. It became a symbol of terror, of genocide, and of the Holocaust.

When they say " We will never forget Auschwitz", they mean "we will never forget the terror, the genocide, the holocaust".