 Race was a central theme in some of Heinlein's fiction.The most prominent and controversial example is "Farnham's Freehold", which casts a white family into a future in which white people are the slaves of cannibalistic black rulers.In the 1941 novel "Sixth Column" (also known as "The Day After Tomorrow"), a white resistance movement in the United States defends itself against an invasion by an Asian fascist state (the "Pan-Asians") using a "super-science" technology that allows ray weapons to be tuned to specific races.