She operated from her father's hotel in Front Royal, Virginia, and provided valuable information to Confederate General Stonewall Jackson in 1862.

A board of inquiry exonerated her of murder, but sentries were posted around the house and officers kept close track of her activities.

"[15] She conveyed those secrets to Confederate officers via her slave Eliza Hopewell, who carried them in a hollowed-out watch case.

[citation needed] General James Shields and his staff gathered in the parlor of the local hotel in mid-May 1862.

That night, she rode through Union lines, using false papers to bluff her way past the sentries, and reported the news to Colonel Turner Ashby, who was scouting for the Confederates.

When the Confederates advanced on Front Royal on May 23, Boyd ran to greet Stonewall Jackson's men, avoiding enemy fire that put bullet holes in her skirt, as according to her memoir.

[23] She was finally captured by Union officials on July 29, 1862, after her lover gave her up, and they brought her to the Old Capitol Prison in Washington, D.C. the next day.

She subsequently began touring the country giving dramatic lectures of her life as a Civil War spy.