This is a subject very close to my heart.
If you are interested, please read "If this is a man" by Primo Levi (Se questo è un uomo). It is one of the most important books of the 20th Century and written by a man who lived through the horrors , survived and felt he owed a duty to tell the story of those who did not.
This is the preface:
You who live safe
In your warm houses,
You who find, returning in the evening,
Hot food and friendly faces:
Consider if this is a man
Who works in the mud
Who does not know peace
Who fights for a scrap of bread
Who dies because of a yes or a no.
Consider if this is a woman,
Without hair and without name
With no more strength to remember,
Her eyes empty and her womb cold
Like a frog in winter.
Medititate that this came about:
I commend these words to you.
Carve them in your hearts
At home, in the street,
Going to bed, rising;
Repeat them to your children,
Or may your house fall apart,
May illness impede you,
May your children turn their faces from you.
One of the very sad truisms of History, is that mankind does not always learn from the last.