Maggie Simpson was detected in the Shenandoah Valley in the fall of 1864. She was arrested and briefly jailed at Harper's Ferry.
A soldier in the provost marshal's office said that Simpson was "another of the 'questionable characters' in the personification of a female woman clad so snugly in a soldier's uniform." He further said that Simpson "was by no means an 'ornament to her sex.' On the whole, she was rather a scaly looking specimen" and had "a face similar to a crocodile and a voice as sweet as a cracked fiddle or an old cow bell or bellows!"
She was sent to Fort McHenry October 20, 1864 and put in the civilian area of the prison. Her guard there noted Simpson's lack of beauty, writing that "she was not a very good looking girl. She had curly hair." The Baltimore provost marshal sent her to the city jail for thirty days, a sentence which was levied not for her alleged Confederate sympathies, bur for being a women disguised as a soldier.