In April 1861, President Abraham Lincoln suspended the writ of habeas corpus along the military line between Washington, D.C., and Philadelphia. This allowed army officers to arrest and indefinitely detain persons who were interfering with military operations in the area. When John Merryman, a wealthy Marylander suspected of burning bridges to prevent the passage of U.S. troops to Washington, was detained in Fort McHenry, the chief justice of the...