The Appomattox campaign was a series of American Civil War battles fought March 29 April 9, 1865, in Virginia that concluded with the surrender of Confederate General Robert E. Lee's Army of Northern Virginia to forces of the Union Army (Army of the Potomac, Army of the James and Army of the Shenandoah) under the overall command of Lieutenant General Ulysses S. Grant, marking the effective end of the war.

As the RichmondPetersburg campaign (also known as the siege of Petersburg) ended, Lee's army was outnumbered and exhausted from a winter of trench warfare over an approximately 40 mi (64 km) front, numerous battles, disease, hunger and desertion. Grant's well-equipped and well-fed army was growing in strength. On March 29, 1865, the Union Army began an offensive that stretched and broke the Confederate defenses southwest of Petersburg and cut their supply lines to Petersburg and the Confederate capital of Richmond, Virginia. Union victories at the Battle of Five Forks on April 1, 1865, and the Third Battle of Petersburg, often called the Breakthrough at Petersburg, on April 2, 1865, opened Petersburg and Richmond to imminent capture. Lee ordered the evacuation of Confederate forces from both Petersburg and Richmond on the night of April 23 before Grant's army could cut off any escape. Confederate government leaders also fled west from Richmond that night.

The Confederates marched west, heading toward Lynchburg, Virginia, as an alternative. Lee planned to resupply his army at one of those cities and march southwest into North Carolina where he could unite his army with the Confederate army commanded by General Joseph E. Johnston. Grant's Union Army pursued Lee's fleeing Confederates relentlessly. During the next week, the Union troops fought a series of battles with Confederate units, cut off or destroyed Confederate supplies and blocked their paths to the south and ultimately to the west. On April 6, 1865, the Confederate Army suffered a significant defeat at the Battle of Sailor's Creek, Virginia, where they lost about 7,700 men killed and captured and an unknown number wounded. Nonetheless, Lee continued to move the remainder of his battered army to the west. Soon cornered, short of food and supplies and outnumbered, Lee surrendered the Army of Northern Virginia to Grant on April 9, 1865, at the McLean House near the Appomattox Court House, Virginia.

The American Civil War (April 12, 1861 – May 9, 1865; also known by other names) was a civil war in the United States between the Union (states that remained loyal to the federal union, or "the North") and the Confederacy (states that voted to secede, or "the South"). The central cause of the war was the status of slavery, especially the expansion of slavery into territories acquired as a result of the Louisiana Purchase and the Mexican–American War. On the eve of the Civil War in 1860, four million of the 32 million Americans (~13%) were enslaved black people, almost all in the South.The practice of slavery in the United States was one of the key political issues of the 19th century. Decades of political unrest over slavery led up to the Civil War. Disunion came after Abraham Lincoln won the 1860 United States presidential election on an anti-slavery expansion platform. An initial seven southern slave states declared their secession from the country to form the Confederacy. Confederate forces seized federal forts within territory they claimed. The last-minute Crittenden Compromise tried to avert conflict but failed; both sides prepared for war. Fighting broke out in April 1861 when the Confederate army began the Battle of Fort Sumter in South Carolina, just over a month after the first inauguration of Abraham Lincoln. The Confederacy grew to control at least a majority of territory in eleven states (out of the 34 U.S. states in February 1861), and asserted claims to two more. Both sides raised large volunteer and conscription armies. Four years of intense combat, mostly in the South, ensued.

During 1861–1862 in the war's Western Theater, the Union made significant permanent gains—though in the war's Eastern Theater the conflict was inconclusive. On January 1, 1863, Lincoln issued the Emancipation Proclamation, which made ending slavery a war goal, declaring all persons held as slaves in states in rebellion "forever free." To the west, the Union destroyed the Confederate river navy by the summer of 1862, then much of its western armies, and seized New Orleans. The successful 1863 Union siege of Vicksburg split the Confederacy in two at the Mississippi River. In 1863, Confederate General Robert E. Lee's incursion north ended at the Battle of Gettysburg. Western successes led to General Ulysses S. Grant's command of all Union armies in 1864. Inflicting an ever-tightening naval blockade of Confederate ports, the Union marshaled resources and manpower to attack the Confederacy from all directions. This led to the fall of Atlanta in 1864 to Union General William Tecumseh Sherman and his march to the sea. The last significant battles raged around the ten-month Siege of Petersburg, gateway to the Confederate capital of Richmond.

The Civil War effectively ended on April 9, 1865, when Confederate General Lee surrendered to Union General Grant at the Battle of Appomattox Court House, after Lee had abandoned Petersburg and Richmond. Confederate generals throughout the Confederate army followed suit. The conclusion of the American Civil War lacks a clean end date: land forces continued surrendering until June 23. By the end of the war, much of the South's infrastructure was destroyed, especially its railroads. The Confederacy collapsed, slavery was abolished, and four million enslaved black people were freed. The war-torn nation then entered the Reconstruction era in a partially successful attempt to rebuild the country and grant civil rights to freed slaves.

The Civil War is one of the most studied and written about episodes in the history of the United States. It remains the subject of cultural and historiographical debate. Of particular interest is the persisting myth of the Lost Cause of the Confederacy. The American Civil War was among the earliest to use industrial warfare. Railroads, the telegraph, steamships, the ironclad warship, and mass-produced weapons saw wide use. In total the war left between 620,000 and 750,000 soldiers dead, along with an undetermined number of civilian casualties. President Lincoln was assassinated just five days after Lee's surrender. The Civil War remains the deadliest military conflict in American history. The technology and brutality of the Civil War foreshadowed the coming World Wars.