Harriet Tubman was one of the great American heroes of the nineteenth century. Showing remarkable courage, she guided more than three hundred fellow slaves to freedom after she first escaped slavery by crossing into free territory in the United States north. Not content to simply enjoy her own freedom, she ventured back into slave states nineteen times to lead friends, family, and strangers to freedom, sometimes guiding people on foot all the way to Canada.

What drove Miss Tubman to such brave action? A woman of deep faith, she at one time said this: “I always told God, I’m going to…