In April 1861, Confederate forces attacked U.S. troops at Fort Sumter in South Carolina, plunging the country into civil war. Moving quickly against the insurrection, President Abraham Lincoln called up the militia and suspended the writ of habeas corpus—a legal order enabling an individual to seek release from unlawful detention. In suspending that privilege, Lincoln exercised an authority constitutionally reserved for Congress. Lincoln then called the entire Congress into extraordinary session, where he sought congressional approval of his actions.