Dr. Mary Edwards Walker

Dr. Mary Edwards Walker wears trousers beneath her dress in this mid-nineteenth century carte-de-visite photograph. (That outfit, known as a Bloomer costume, was popular among women's rights advocates at the time.) A New York-born abolitionist and Union surgeon, Walker was captured by Confederates in April 1864. She was incarcerated at Castle Thunder Prison in Richmond, where she remained until August 12, when she was released in a prisoner of war exchange. After the war, she was the first woman to be awarded the Congressional Medal of Honor, the nation's highest military honor.