North Carolina, Tennessee, and Arkansas followed over the following two months. Secession sentiment was strong in Missouri and Maryland, but did not prevail; Kentucky remained neutral.[183] The Fort Sumter attack rallied Americans north of the Mason-Dixon line to defend the nation.
As States sent Union regiments south, on April 19, Baltimore mobs in control of the rail links attacked Union troops who were changing trains. Local leaders' groups later burned critical rail bridges to the capital and the Army responded by arresting local Maryland officials. Lincoln suspended the writ of habeas corpus where needed for the security of troops trying to reach Washington.[184] John Merryman, one Maryland official hindering the U.S. troop movements, petitioned Supreme Court Chief Justice Roger B. Taney to issue a writ of habeas corpus. In June, in Ex parte Merryman, Taney, not ruling on behalf of the Supreme Court,[185] issued the writ, believing that Article I, section 9 of the Constitution authorized only Congress and not the president to suspend it. But Lincoln persisted with the policy of suspension in select areas.[186][187]

Union military strategy
Lincoln took executive control of the war and shaped the Union military strategy. 