Who or what is the antagonist of the story "An Occurrence at Owl Creek Bridge"?

The human antagonist(s) in Ambrose Bierce's "An Occurrence
at Owl Creek Bridge" would have to be the Union soldiers who are about to hang the
protagonist, Peyton Farquar. The Union soldiers are Farquar's direct enemies, and with
the lack of other characters in the story, there can be little debate on this question.
(The Union spy who tricked Farquar could also be considered a minor antagonist.) It
could also be argued that the hangman's noose serves as an antagonist: It is the rope
that Farquar hopes to somehow evade as he stands upon the railroad trestle awaiting his
fate. And it is the rope that eventually serves as the instrument of his
death.