Fritz Leiber, "Try and Change the Past" (1958) related to American Science Fiction: Nine Classic Novels of the 1950s:
When the Library of America put out a collection of American science fiction--about which, yay!--they also organized a very interesting companion website. Do they do this for other works, and if not, why not? (Note to self: try to talk with whoever plans these projects over there.) The collection of novels from the 1950s includes Fritz Leiber's award-winning The Big Time, where the Spiders and the Snakes fight each other using time-travel technology. So, for the companion website, the LoA put up this story of Leiber's that takes place in the same universe: it involves the same mysterious time-travel armies and the same theory of time's Conservation of Reality--try to change the past and the timeline will find some way to fix itself.
Now, if that sounds somewhat familiar, you might be thinking of Alfred Bester's 1958 "The Men Who Murdered Muhammed," whereby time-travelers go back to change the past and find that, whoops, they can't do anything (except exile themselves). Maybe there was something in the water back then that made science fiction writers fatalistic? After all, in another six years, H. Beam Piper, who wrote extensively about time travel and changing history, committed suicide. I digress, but you get the point: time travel and fatalism are either a natural pair or strange bedfellows, depending on your view of history. As this story concludes, "how’s a person going to outmaneuver a universe that ﬁnds it easier to drill a man through the head that way [with a tiny meteorite that resembles a .32 bullet] rather than postpone the date of his death?"
This story is pretty thin--it's not a surprise that Bester was shortlisted for the Hugo for short story in 1959 and Leiber had to console himself with his Hugo for novel from 1958. Today, if a writer wrote this story, it would probably be used as a way to drum up interest in their novel--if it didn't sell, it would be posted free to the author's website. (Heck, maybe that's how Leiber used this story.)
The story takes a while to set out the rules of the universe--Snakes, Spiders, Conservation of Reality--and then goes on to show how a man tries to change the past and fails. So it's really just an anecdote to prove that Conservation principle. There's an eerie, Twilight Zone quality to the way that the universe refuses to be changed by one man; but there's also just a hell of a lot of depression. After all, this guy tries to save his life and comes to realize that he's been on a suicidal streak for a while.
Which brings us to the weirdness of The Big Time itself, which is a huge war novel. (I mean, the war is huge; the novel itself is pretty short.) Here are two sides named after animals, not principles or whatever else the war is about. As Leiber himself noted, he named them that "to keep them mysterious and unpleasant, as major powers always are, inscrutable and nasty." So here's great power and huge danger all in the service of--what? This story only touches on that aspect; but it's almost hard to imagine the guy who wrote the happy-go-lucky Fafhrd and Gray Mouser tales writing this depressing stuff. (It's easier once you remember that he also wrote Our Lady of Darkness, a novel about drunkenness and madness.)