Mark Twain

I am reading Mark Twain's A Connecticut Yankee in King Arthur's Court. Though I've read it before and some of his work in the last 5 years I was shocked by some of his language and prejudices:

'The thought was forced upon me: “The rascals (= prisoners of war) they have served other people so in their day; it being their own turn, now, they were not expecting any better treatment than this; so their philosophical bearing is not an outcome of mental training, intellectual fortitude, reasoning; it is mere animal training; they are white Indians.”

Look at Internet Archive and you will find lots of books on "White Indians."