Sidewise in Time

"Sidewise in Time" is a science fiction short story by American writer Murray Leinster (1896-1975) first published in the June 1934 issue of Astounding Stories. It is regarded as the first example of the alternate history genre of science fiction in which one or more historical events happened differently than they did in our own historical reality. The Sidewise Award for Alternate History, established in 1995 to recognize the best alternate history stories and novels of the year, was named in honor of this work.