She's known for her work on the Underground Railroad guiding slaves to freedom in the north starting in 1849, but few know that during the American Civil War, Harriet Tubman was an exceptionally capable Union Army spy. The knowledge and skills she had gained made her a perfect spy for the Union. Former slaves scouted behind Confederate lines, and she selected bridges for destruction to cut off supply lines. Under her command African-American Union soldiers saved hundreds of people in a raid on the Combahee River Ferry. She is one of the most celebrated American women in history.