Why is Peyton Farquhar not involved with the army in "An Occurrence at Owl Creek Bridge"?

The reason Peyton Farquhar is not a soldier, officer, or part of the army is not given.  The author says only that "circumstances of an imperious nature which it is unneccessary to relate here, had prevented him from taking service with the gallant army".  Apparently, there are significant reasons that Farquar is not a part of the military, but the reasons themselves are not important enough to be revealed and examined in the story.

What is clear, however, is that Farquhar's sympathies are unquestioningly with the Confederacy in the Civil War.  As a slave owner, he is "an original secessionist and ardently devoted to the Southern cause".  Although he is prohibited by unnamed circumstances from joining up, he longs for "the larger life of the soldier, the opportunity for distinction".  He is "a civilian who (is) at heart a soldier" who will do what he can in whatever capacity to help the Southern cause, and it is because of this zeal that he finds himself in the predicament of imminent execution at the hands of the Union Army at Owl Creek Bridge.