Harriet Tubman was a slave in Maryland who escaped to freedom using the Underground Railroad, risking her life to return and rescue over 300 slaves over 19 trips. She worked as a Union cook, spy, and scout during the Civil War and helped free over 700 slaves in a raid at Harper's Ferry. The Underground Railroad was an informal network of secret routes and safe houses used by slaves to escape to freedom in the northern United States and Canada, with some routes traveling through the Great Lakes and all leading to Canada.