6. Harriet Tubman —
A Union spy during the American Civil War, Harriet Tubman was not supposed to make it past the Mason-Dixon line. A woman born into slavery, she escaped the Jim Crow's clutches and subsequently made more than thirteen missions to rescue more than 70 slaves. Using a network of anti-slavery activists and safe houses known as the Underground Railroad, Tubman would go on to help John Brown to recruit men for his raid on Harper's Ferry and when the war era ended, she fought for women's suffrage.