Soon after the election of President Abraham Lincoln, eleven southern states secede from the Union and form the Confederacy. When Lincoln declines to surrender Fort Sumter in the harbor of Charleston, South Carolina, Confederate forces fire upon and capture the fort. Lincoln then declares that an insurrection exists and calls on Northerners to volunteer for military service. Lincoln calls Congress into emergency session on July 4 but does not seek a formal declaration of war. After four brutal years of fighting, the South surrenders in April 1865.