The first paragraph in Part 2 of "An Occurrence at Owl Creek Bridge" describes Peyton Farquhar and explains his devotion to the Southern cause.
No service was too humble for him to peform in the aid of the South, no adventure too perilous for him to undertake if consistent with the character of a civilian who was at heart a soldier, and who in good faith and without too much qualification assented to at least a part of the frankly villainous dictum that all is fair in love and war.
Farquhar asks a number of questions about the Owl Creek bridge because he sees an opportunity to help the Confederate army by sabotaging the bridge, thereby holding back the Union Army's advance. He owns a big, beautiful plantation which is situated only thirty miles away from the Owl Creek bridge. Like a lot of other plantations, his could be destroyed and looted by the Union soldiers, his slaves all set free, and his family reduced to destitution without even enough food to eat after the Yankees had carried off all the grain, smoked meat, chickens and livestock. So Farquahar is strongly motivated in at least two ways. He wants to protect himself and his family from the foraging Yankees, and he wants to strike an important blow for the Southern cause.
"The Yanks are repairing the railroads," said the man, "and are getting ready for another advance."
The Federal scout posing as a Confederate soldier claims to have been near the bridge about a month before. He is Farquhar's only source of information about the location and current conditions. Farquhar's questions are all seeking essential information for a man intent on single-handedly destroying a bridge which is heavily guarded by Yankees and of the utmost importance to their advance, even though it is only a simple wooden railroad bridge over an insignificant creek. Naturally the scout makes it sound fairly easy for a single man to slip past the picket post and to set fire to the wooden bridge which has "a great quantity of driftwood against the wooden pier at this end of the bridge." (The driftwood may have been cleared away long ago.)
The scout never suggests that Farquhar try to set fire to the bridge, but both men seem to understand each other. Farquhar will be walking into a trap. The Yankees know that there are plenty of Confederate sympathizers and "adventurists" who would like to take unilateral action against them. This is apparently why they have sent out scouts disguised as Confederate soldiers as what might be described as agents provocateurs. By actually enticing saboteurs to the strategic bridge, the Union officers will have a pretty good idea of how many might be coming and from which directions. As Ambrose Bierce says, this is all part of "the frankly villainous dictum that all is fair in love and war."
Bierce knew a lot about the Civil War. He served in active combat with the Union army and wrote many Civil War stories in later life. His experience in the war contributed to his famous pessimistic attitude about human nature.
Farquhar was “ardently devoted to the Southern cause.” According to the story, he was unable to join the army, for reasons untold by the narrator. Farquhar, however, was eager to aid the cause and receive distinction for his actions. When the Federal scout, disguised as a Confederate soldier, happened upon Farquhar’s plantation, he sees his opportunity. He begins to ask questions of the soldier about news from the front. The soldier tells him that the Owl Creek bridge has been repaired and that any civilian caught interfering with the bridge would be hanged. Farquhar begins to ask questions of the soldier about the bridge. At first the questions are seemingly innocent, beginning with the distance to the bridge. The questions begin to become more specific about the guarding of the bridge. Farquhar then gives the soldier a scenario in which a civilian overcomes the guards and asks what could be accomplished. The questions ultimately end in the soldier suggesting how Farquhar could sabotage the bridge by burning the driftwood that had lodged against the pier.