Robinett, Stephen. "Helbent 4"
Divergence: c 202 BCE
Summary: A "man" sent to fight aliens returns to Earth 300 years later but it isn't the Earth he left. The new one thinks he's the menace.
Published: In Galaxy, October 1975; The Best from Galaxy Volume IV (ed. Jim Baen), Award 1976 and Ace 1978 (0441054641); Best Science Fiction Stories of the Year, Fifth Annual Collection (ed. Lester Del Rey), Dutton 1976 (052506494X); and The 1976 Annual World's Best SF (eds. Donald A. Wollheim and Arthur W. Saha), DAW 1976.
Original in: English.
Translation: French by Daphné Halin as "Helbent IV", in [[title unknown]], Galaxie 1977.
Translation: Italian by Gabriele Tamburini as "Helbent 4", in Il pianeta dei venti. Il meglio della fantascienza nel 1975 (eds. Donald A. Wollheim and Arthur W. Saha), Armenia 1977.
Translation: Italian by Renato Pera as "Helbent 4", in Il Meglio di Galaxy 4 (ed. Jim Baen), Mursia 1980.