What are the themes of the story "An Occurrence at Owl Creek Bridge"?

Because Peyton Farquhar
believes that "all is fair in [...] war," he behaves in a manner that proves it, and
he is hanged for this behaviors, readers can come to the conclusion that such a belief is an
inappropriate one.  Farquhar, the narrator tells us, feels like a soldier at heart, and he
obviously believes that, during war, one might do things that would, other times, be considered
wrong or unacceptable; this is what the expression signifies.  In other words, for him -- and
for others who share his belief -- the ends justify the means; put differently, the goals of war
justify whatever brutality is necessary to achieve those goals.  Farquhar is executed by the
Union army for believing this and for acting on this belief, and so we might infer that such a
belief is both wrong and dangerous.  

In addition to a denunciation of the
belief that all is fair in war, Bierce seems determined to point out the extent of the toll that
war takes.  It doesn't simply ruin the lives of soldiers who must fight and kill and die, but
also the lives of civilians.  War causes suffering and death, no matter what, and Bierce appears
to discourage it as an appropriate way of negotiating change.