Hull, E. M. "The Flight that Failed"
Divergence: c 1941 CE
Summary: A man from a world in which Germany won World War II comes back to a flight that had been shot down to save it and change his past so that Germany lost.
Published: In Astounding, December 1942; Science Fiction Adventures in Dimensions (ed. Groff Conklin), Vanguard 1953, Berkley 1965; and Adventures in Dimension (ed. Groff Conklin), Grayson 1955.