Modernism does not introduce new themes into literature, instead it treats the old themes in a new way. "The Short Happy Life of Francis Macomber" is about courage, the relationships between men and women, and what makes life meaningful. All these themes are found in Victorian literature, where men are rewarded for courage, conventional relationship patterns are reinforced, and the meaning of life appears to be of cosmic importance. Hemingway's modernist story subverts all these tropes.
While Macomber is punished for cowardice by the sneering of his unfaithful wife, he is not rewarded when he shows courage but punished even more severely by sudden execution. It was sensible of him to run away from the lion, and he might just as well have continued the same policy with the charging buffalo. In a Victorian story, Macomber's display of courage would have given him the moral authority to assert dominance over his wife, whereas in this one, he dies almost as soon as he becomes powerful. His life gains meaning for a few hours, but it is only meaningful to him, not in cosmic terms, and his short happy life is soon over. In these ways, "The Short Happy Life of Francis Macomber" is a modernist short story, which presents the action without moralizing or portentous conclusions.