<human>:  What happened in the Battle of Gettysburg during the American Civil War?
<bot>: The Battle of Gettysburg was one of the most significant battles of the American Civil War. It took place from July 1–3, 1863, near the town of Gettysburg, Pennsylvania, and involved the Union Army of the Potomac, under the command of Major General George Gordon Meade, and the Confederate Army of Northern Virginia, under the command of General Robert E. Lee. The battle resulted in a decisive victory for the Union, with over 23,000 Confederate casualties and over 28,000 Union casualties. As a result of the battle, Lee's last major offensive against the Union was thwarted, and the Confederate Army of Northern Virginia was forced to retreat. The Battle of Gettysburg was seen both as a turning point in the war and as a symbol of the war's immense cost in human lives.