"Dark Interlude" by Mack Reynolds and Fredric Brown
A traveller is sent back to an earlier time (early 20th century America?). He reveals innocently that he's "at least one-fourth" black, and is killed by an angry racist farmer.
Recap of the story
“He said that by his time–starting after the war of
something-or-other, I forget its name–all the races had blended into
one. That the whites and the yellows had mostly killed one another off
and that Africa had dominated the world for a while, and then all the
races had begun to blend into one by colonization and intermarriage
and that by his time the process was complete. I just stared at him
and asked him, ‘You mean you got n***** blood in you?’ and he said,
just like it didn’t mean anything, ‘At least one-fourth.’”
Since the other story is also by Brown "Recessional," (see below) you probably have a collection by Brown, such as Nightmares and Geezenstacks
Description of Recessional
The book (American, I think) also contained a story about two armies struggling in battle, one all in black, one all in white. It becomes clear at the end of the story that they are actually chess pieces and are doomed to keep repeating their struggle. I'd love to find out the title of the book itself.
Published for the first time in the collection Nightmares and
Geezenstacks in 1961, this very short story by Fredric Brown tells the
fight lead by a soldier in the war opposing the Whites (his camp)
against the Blacks (the enemy). The dreadful losses suffered by his
camp make him wonder about the absurdity of war and the death of many
companions on the battlefield. But anyway, what really matters is
victory !
Quote from the story
Tibault, you were wrong, you were— But what is happening now? The very
Earth tilts; one side of the battlefield rises and we are
sliding—White and Black alike—into— —into a monstrous box and I see
that it is a mass coffin in which already lie dead - IT IS NOT FAIR;
WE WON! GOD, WAS TIBAULT RIGHT? IT IS NOT JUST; WE WON! The King, my
liege lord, is sliding too across the squares—.