
(This book is also known by the title "Sixth Column") An Asian totalitarian government using advanced technology conquers America practically overnight because America has basically disarmed itself. A supersecret laboratory becomes the last hope for America when a major breakthrough in technology is made. Unfortunately the breakthrough experiment also kills the lead researcher and most of the staff of the laboratory, leaving less than a dozen men alive, only one of them a scientist. A reserve intelligence Major, whose regular occupation is being an advertising executive, gets to the laboratory just after the experiment has killed most of the staff. His mission as the last free active military officer is to use the resources of the laboratory and the breakthrough (which looks like magic to the Major) to defend America and restore its freedom. The Major has to use his understanding of people in order to organize the resistance and understand the enemy in order to use the breakthrough effectively to win freedom. The difficulties of fighting a totalitarian regieme that has no respect for life are explored. The temptation of great power in the hands of a few is another thread. The battle for freedom must restore power to the people. An entertaining read. Typically Heinlein.
It's among his weakest novels but I'm not sure how anyone would derive "genocide" out of it. IIRC, it was a plot point that the invaders also treated Asian-Americans brutally.
To give another example, he rejected a story by Samuel R. Delany in 1967 - https://www.nyrsf.com/racism-and-science-fiction-.html :
> ... with a note and phone call to my agent explaining that he didn’t feel his readership would be able to relate to a black main character. That was one of my first direct encounters, as a professional writer, with the slippery and always commercialized form of liberal American prejudice: Campbell had nothing against my being black, you understand. (There reputedly exists a letter from him to horror writer Dean Koontz, from only a year or two later, in which Campbell argues in all seriousness that a technologically advanced black civilization is a social and a biological impossibility. . . .). No, perish the thought! Surely there was not a prejudiced bone in his body! It’s just that I had, by pure happenstance, chosen to write about someone whose mother was from Senegal (and whose father was from Norway), and it was the poor benighted readers, out there in America’s heartland, who, in 1967, would be too upset. . . .
But he was a racist all his life. You ever wonder why the 'Golden Age' SF almost all has white men as the main character, with humans almost always winning over aliens? It's in part because his big influence on SF caused his racism to permeate the stories I read and enjoyed as a kid.
Here's a paraphrase from Asimov (Campbell, btw, felt that Jews were a superior species of human), quoted at https://andrewhickey.info/2017/08/09/the-prometheans-wheels-... :
> Campbell’s racist views had a stifling effect on his writers even in the 1940s – Asimov said that one reason his stories never featured aliens was because Campbell would always insist that humans were superior to aliens, because he couldn’t cope with a worldview where white American men weren’t the best, so the left-leaning Asimov just didn’t write stories with aliens in, to avoid the problem.
Heinlein's 1941 "Sixth Column" was an idea originally developed by Campbell. Quoting https://en.wikipedia.org/wiki/Robert_A._Heinlein#Race :
> The idea for the story was pushed on Heinlein by editor John W. Campbell, and Heinlein wrote later that he had "had to re-slant it to remove racist aspects of the original story line" and that he did not "consider it to be an artistic success."