 Robert Heinlein was among the best-selling science fiction authors of the 1940s and 1950s, along with Isaac Asimov and Arthur C. Clarke; they were known as the "big three" that dominated U.S. science fiction.In contrast to the others, Heinlein firmly endorsed the anti-communist sentiment of the Cold War era in his writing.Heinlein served in the U.S. Navy for five years after graduating from the United States Naval Academy in 1929.