The Civil War

The United States — the Union — included the Northern and Western states, joined by slaveholding border states that remained loyal, with 2.5 million free inhabitants and 500,000 enslaved people. The Confederate States of America comprised Texas, Arkansas, Louisiana, Tennessee, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, and Virginia. The Union had overwhelming advantages in population, factories, money, and food production: 1.1 million factory workers to the Confederacy’s 111,000. Enslaved people were not bystanders; from the first days of the war, they acted to secure their own liberty, and nearly 200,000 Black men eventually served in Union forces.

Decades of conflict over the expansion of slavery — the Missouri Compromise, the Compromise of 1850, the Kansas-Nebraska Act, the Dred Scott decision, and John Brown’s raid — had split the nation. In 1860 Abraham Lincoln won the presidency on a Republican platform opposing slavery’s spread into the territories. Many white Southerners feared that Lincoln would eventually move against slavery itself; rather than face a future in which Black people might become free citizens, seven states — beginning with South Carolina — seceded before he took office, citing states’ rights. In his inaugural address on March 4, 1861, Lincoln declared secession unconstitutional and the Union perpetual.

Fort Sumter and mobilization (1861). Confederate batteries opened fire on Fort Sumter in Charleston Harbor on April 12, 1861; after 34 hours, the garrison surrendered. Four more states seceded.

A war of attrition (1862). Union forces under Ulysses S. Grant won victories in the West, while in Virginia Robert E. Lee’s Army of Northern Virginia repeatedly defeated Union offensives. After Lee’s invasion of Maryland was stopped at Antietam in September 1862, Lincoln issued the preliminary Emancipation Proclamation.

The turning year (1863). Emancipation took effect on January 1, and the U.S. Colored Troops were created in May. In July, Lee’s second invasion of the North was defeated at Gettysburg, and Grant captured Vicksburg, giving the Union control of the Mississippi.

Total war (1864–1865). Grant, praised and criticized for his willingness to accept heavy casualties, pressed Lee in Virginia and laid siege to Petersburg. Lincoln won reelection in November 1864. Richmond fell on April 2, 1865, and Lee surrendered at Appomattox Court House on April 9.

• Antietam (September 1862): gave Lincoln the victory he needed to announce emancipation.
• Emancipation (January 1863): made the war a war against slavery, opened the army to Black soldiers, and discouraged Britain and France from recognizing the Confederacy.
• Gettysburg and Vicksburg (July 1863): ended the Confederacy’s last major invasion of the North and split it in two.

The Confederacy collapsed. Lee’s surrender was followed by the surrender of other Confederate forces over the next weeks; President Andrew Johnson later declared the war officially over. The Thirteenth Amendment, ratified in December 1865, abolished slavery throughout the United States. Union victory ended forever the claim that state sovereignty superseded federal authority. Abroad, the Confederacy never won recognition from a single foreign government.

The war killed an estimated 620,000 soldiers — roughly two percent of the population; hundreds of thousands died of disease. It devastated much of the South and left a generation of widows, orphans, and disabled veterans. Lincoln, assassinated days after Appomattox, became a national martyr.

It also transformed the Constitution and the nation’s idea of freedom. Four million people were freed. The Fourteenth and Fifteenth Amendments promised citizenship, equal protection, and voting rights regardless of race. Whether those promises would be kept was the central question of Reconstruction — and of much of the century that followed.