
Fort McHenry in Baltimore harbor held political prisoners during the 1861 secession crisis. After Gettysburg, 7,000 prisoners from the Army of Northern Virginia were transported here. (Sandra Foyt/Alamy Stock Photo)
Fort McHenry in Baltimore harbor held political prisoners during the 1861 secession crisis. After Gettysburg, 7,000 prisoners from the Army of Northern Virginia were transported here. (Sandra Foyt/Alamy Stock Photo)