Sixth Column (also known as The Day After Tomorrow) by Robert A. Heinlein, first published in 1949, is a military science fiction novel set in a future where the United States has been conquered by an Asian invader known as the PanAsians.
The story follows a small group of surviving American scientists hidden in a secret mountain laboratory. Led by physicist Dr. Calhoun, the team has developed advanced technologies capable of targeting enemies based on racial and biological differences—allowing them to fight back without harming fellow Americans. As they devise a plan to overthrow the oppressive regime, they launch a covert resistance campaign under the guise of a new religious movement, using their scientific “miracles” to inspire rebellion.
Sixth Column explores themes of resistance, identity, and the misuse of science, but it has long been controversial for its racial overtones and portrayal of the PanAsian conquerors. While Heinlein inherited the story outline from editor John W. Campbell, he reworked it extensively to focus more on moral and strategic dilemmas rather than xenophobic revenge.
Despite its problematic elements, the novel is notable for its early treatment of asymmetric warfare, the intersection of science and ideology, and the complexities of mounting a rebellion under extreme oppression. It remains a provocative and historically significant entry in Heinlein’s early body of work.
