The Battle of Gettysburg (locally /ˈɡɛtɨsbɜrɡ/ (audio speaker iconlisten), with an ss sound), was fought July 1–3, 1863. The battle took place in and around the town of Gettysburg, Pennsylvania. It was the battle with the largest number of casualties in the American Civil War. Gettysburg is often called the war's turning point. Union Major General George G. Meade's Army of the Potomac stopped attacks by Confederate General Robert E. Lee's Army of Northern Virginia. This ended Lee's second invasion of the North. Lee began to move his men back to Virginia on July 4. Between 46,000 and 51,000 soldiers from both armies were casualties in the three-day battle.

The Siege of Vicksburg ended on the same day, also a Union victory.

That November, a cemetery for those who died there was opened at the Gettysburg National Cemetery. President Abraham Lincoln gave a speech called the Gettysburg Address at the ceremony to open the cemetery and honor the dead soldiers on both sides.