[2] He served as a Navy hospital corpsman (medic) with the Marine Corps in the Pacific during World War II, and began his writing career as a Talmudic scholar around 1950.

As reported at the time in the February 20, 1962, Yonkers daily, the Herald Statesman, Rabbi Arnold Weinberger officiated at his wedding to Miss Grania Kaiman, which took place at the home of Damon Knight.

He was a member of the Swordsmen and Sorcerers' Guild of America (SAGA), a loose-knit group of Heroic Fantasy authors founded in the 1960s, some of whose works were anthologized in Lin Carter's Flashing Swords!

Other speculative fiction includes the Peregrine novels, comic views of Europe shortly after the fall of Rome; the Jack Limekiller stories, about a Canadian living in an imaginary Central American country modelled after Belize during the 1960s; and the stories of Dr. Eszterhazy, an erudite Sherlock Holmesian figure living in the mythical Scythia-Pannonia-Transbalkania, the waning fourth-largest empire in Europe.

In Joyleg, A Folly, written in collaboration with Ward Moore, a veteran of the American Revolutionary War (and of the Whiskey Rebellion) is found alive and very well in the Tennessee backwoods, having survived over the centuries by daily soaks in whisky of his own making to hilariously face the world of the 1960s.

Davidson also wrote dozens of short stories that defy classification, and the Adventures in Unhistory essays, which delve into puzzles such as the identity of Prester John and suggest solutions to them.

Later essays were handicapped by a lack of resources in the libraries of the small towns where Davidson lived in the pre-Internet era, but are enlivened by the style and bold speculation.

Especially in his later works, Davidson included elements that beginning writers are told to avoid, such as page-long sentences with half a dozen colons and semi-colons, or an apparently irrelevant digression in the opening pages of a story.