The correct answer is: During the civil war, ordinary individuals who wanted to aid the war effort acted as spies.
Indeed, the Dark Game clearly explains that because Elizabeth Van Lew was seen by he chauvinistic society as just a woman; she was able to fool Southern Confederate authorities that her frequent visits to the Richmond prison where Union soldiers where done on the grounds on Victorian, Christian charity.
Both sides of the Civil war used women as spies since they were rarely noticed or found suspicious. Van Lew played on this sexist outlook in order to effectively gather information on the Confederate armies and to assist prisoner Union soldiers and Southern army defectors. She ran the entire spy ring from her Richmond home.
