Even as Lincoln took office in March 1861, Confederate forces threatened the federal-held Fort Sumter in Charleston, South Carolina. On April 12, after Lincoln ordered a fleet to resupply Sumter, Confederate artillery fired the first shots of the Civil War. Sumter's commander, Major Robert Anderson, surrendered after less than two days of bombardment, leaving the fort in the hands of Confederate forces under Pierre G.T. Beauregard. Four more southern states–Virginia, Arkansas, North Carolina and Tennessee –joined the Confederacy after Fort Sumter. Border slave states like Missouri, Kentucky and Maryland did not secede, but there was much Confederate sympathy among their citizens.
Though on the surface the Civil War may have seemed a lopsided conflict, with the 23 states of the Union enjoying an enormous advantage in population, manufacturing (including arms production) and railroad construction, the Confederates had a strong military tradition, along with some of the best soldiers and commanders in the nation. They also had a cause they believed in: preserving their long-held traditions and institutions, chief among these being slavery.