Thor Meets Captain America - David Brin

Thor Meets Captain America offers an alternate history exploring a chilling scenario behind the Holocaust. In this parallel world, the Nazis narrowly avoid defeat in World War II when they are championed by the gods of the Norse Pantheon. At a dramatic turn, Loki joins the Allies and they prepare a last-ditch raid to blow up Valhalla. With an afterword by the author.
This novella, nominated for a Hugo Award in 1987, was later expanded into an award winning graphic novel, The Life Eaters, with artwork by Scott Hampton.