Cover by Emshwiller.
Lest Darkness Fall (1939) is (arguably) the creator of the alternate-history genre, as it predates nearly any prior example, and set the template. A ridiculously immersive and historically detailed take on the Connecticut Yankee in King Arthur’s Court idea created by a genius polymath (de Camp is the only writer apart from Asimov who wrote a book in every category of the Dewey Decimal System, the kind of guy with a brain that makes you feel like Fred Flintstone), in “Lest Darkness Fall,” a modern man is sent back in time to the darkest final hours of Ancient Rome, where for no other reason than his own comfort and survival, he works to ensure the survival of civilization and prevent the dark ages in the age of the Ostrogoths.
L. Sprague de Camp is the only writer where I ever read him and said, “damn, I want to write like that.” Breezy, readable, with punchy, powerful direct sentences. Many writers of this era were good at atmosphere; de Camp could create people as well, which is much rarer. And he had a wicked sense of humor and sense of satire. Imagine that focus set on the “angels on the head of a pin” non-differences that led to fights among the early Christian sects, for example. The Golden Age of Science Fiction had three true geniuses, and de Camp was one of them.
