When did the Civil War begin?

The Civil War began in 1861 when Confederate forces fired on Fort Sumter in Charleston Harbor, South Carolina at 4:30 a.m. on April 12, 1861, opening the deadliest war in American history that would last four years and kill at least 620,000 soldiers, with some recent estimates as high as 750,000.

The path to war ran through the secession crisis of 1860 to 1861. Abraham Lincoln won the November 6, 1860 presidential election as the Republican nominee opposed to the expansion of slavery, even though he received no electoral votes from the South. South Carolina seceded on December 20, 1860 by unanimous vote of its convention. Mississippi followed January 9, 1861, Florida January 10, Alabama January 11, Georgia January 19, Louisiana January 26, and Texas February 1. The seven seceded states organized the Confederate States of America at a convention in Montgomery, Alabama beginning February 4, 1861, adopted a provisional constitution, and elected Jefferson Davis of Mississippi provisional President on February 9, 1861.

Federal forts in the seceded states became flashpoints. Major Robert Anderson and his small Union garrison occupied Fort Sumter, an unfinished masonry fort on a small island at the entrance to Charleston Harbor. Anderson had moved his troops there from Fort Moultrie on the night of December 26, 1860 to protect them from secessionist mobs. President James Buchanan refused to surrender the fort but also did little to defend it during his last weeks in office.

Lincoln took office on March 4, 1861 and announced he would resupply but not reinforce Fort Sumter. South Carolina governor Francis Pickens informed Confederate authorities, and Confederate President Jefferson Davis ordered General P.G.T. Beauregard to demand surrender. Beauregard's representatives demanded surrender on April 11, 1861. After Anderson refused, Confederate batteries opened fire at 4:30 a.m. on April 12, 1861. The bombardment lasted 34 hours. Anderson surrendered on April 13 with no Union casualties from enemy fire (one Union soldier was killed when a cannon misfired during the surrender salute).

On April 15, 1861 Lincoln issued a proclamation calling for 75,000 volunteers to suppress the rebellion. The call provoked four more states to secede: Virginia on April 17, Arkansas on May 6, Tennessee on May 6 (popular vote June 8), and North Carolina on May 20. The Confederate capital moved to Richmond, Virginia on May 29, 1861. The first major battle, the First Battle of Bull Run (or First Manassas), occurred on July 21, 1861, ending in a Confederate victory that disabused Northerners of any expectation of a quick war.