The American Civil War was the crucible in which the United States was fundamentally remade. Fought from April 12, 1861 to May 26, 1865, it pitted the Union states of the North against eleven Southern states that had seceded to form the Confederate States of America. When the guns finally fell silent, the Confederacy had been dissolved, slavery had been abolished, and four million African Americans had been legally freed from bondage. The war left an estimated 700,000 soldiers dead — more than in any other conflict in American history — along with an undetermined number of civilian casualties.
The conflict had been building for decades. Slavery had been embedded in the American South's economy and social order since colonial times, and as the United States expanded westward, the question of whether slavery would be permitted in new territories generated increasingly bitter political conflict. The 1850s brought a series of crises — the Compromise of 1850, the Kansas-Nebraska Act, the violent struggle over "Bleeding Kansas," the Supreme Court's Dred Scott decision — that each deepened sectional divisions. The election of Abraham Lincoln in 1860, a Republican who opposed slavery's expansion into new territories, was the final provocation. Lincoln had not proposed abolishing slavery where it already existed, but seven slave states in the Deep South refused to accept his presidency and seceded from the Union even before he was inaugurated.
The newly formed Confederacy, led by President Jefferson Davis, began seizing federal forts and other government property across the South. The war began on April 12, 1861, when Confederate artillery opened fire on Fort Sumter, a Union garrison in Charleston Harbor, South Carolina. The attack electrified both sections: waves of patriotic enthusiasm swept across the North and South alike, and military recruitment soared. Four more Southern states seceded in the weeks that followed, bringing Confederate strength to eleven states containing about a third of the country's total population.
The early years of the war were characterized by inconclusive fighting in the eastern theater, where Confederate General Robert E. Lee proved a brilliant and resourceful commander, frustrating one Union general after another. In the western theater, however, the Union made steady gains. Ulysses S. Grant emerged as the most effective Union commander, capturing key fortifications along the Tennessee and Cumberland rivers in early 1862 and then, in a grinding campaign through 1862 and 1863, seizing control of the Mississippi River. The capture of Vicksburg in July 1863 completed Union control of the great river and split the Confederacy in two.
The same month that Vicksburg fell, Lee's ambitious invasion of the north collapsed at the Battle of Gettysburg in Pennsylvania, a three-day engagement of extraordinary ferocity that ended with the Confederate army retreating across the Potomac. Gettysburg marked the high-water mark of Confederate military power.
The character of the war was transformed on January 1, 1863, when Lincoln issued the Emancipation Proclamation, declaring all enslaved people in rebel states to be free. The proclamation did not immediately liberate anyone in areas still controlled by the Confederacy, but it reframed the war as a struggle for human freedom, discouraged European recognition of the Confederacy, and opened the door for African Americans to serve in the Union Army. By war's end, roughly 180,000 Black men had served in Union forces.
Impressed by Grant's results in the west, Lincoln promoted him to command of all Union armies in 1864. Grant pursued a strategy of relentless pressure on all fronts simultaneously, recognizing that the Union's greater population and industrial resources would eventually overwhelm Confederate resistance if the pressure never let up. Union General William Tecumseh Sherman captured Atlanta in September 1864 and then marched his army to the sea, cutting a swath of destruction through Georgia designed to break the Confederate will to fight. The Siege of Petersburg, lasting nearly ten months, gradually strangled the Confederate capital at Richmond.
The end came rapidly in the spring of 1865. Confederate forces abandoned Richmond, and Lee surrendered to Grant at Appomattox Court House on April 9, 1865, in a meeting conducted with remarkable dignity on both sides. The last Confederate forces formally surrendered in late May. Lincoln had lived to see the victory but did not survive it; he was shot by the actor and Confederate sympathizer John Wilkes Booth on April 14, 1865 and died the following morning. The nation then entered the Reconstruction era, wrestling with the enormous challenge of rebuilding the South, reintegrating the former Confederate states, and defining the meaning of freedom for the millions who had just been liberated.
