Why does the soldier visit the Farquhar home?

The soldier visits the Farquhar home to deliver a message and to gather intelligence about the family's loyalty during the Civil War. He poses as a Confederate soldier, seeking assistance from Mrs. Farquhar while subtly probing her husband's political beliefs. This encounter ultimately leads to a critical turning point in the story, as it sets the stage for the events that follow in Ambrose Bierce's "An Occurrence at Owl Creek Bridge."