What was the significance of Gettysburg?

The Battle of Gettysburg, fought July 1 to 3, 1863 in and around the small Pennsylvania town of Gettysburg, was the turning point of the Civil War, halting Confederate General Robert E. Lee's second invasion of the North, costing the Confederacy roughly 28,000 casualties it could not replace, and shifting the strategic momentum permanently to the Union. The battle was the largest engagement ever fought on the North American continent, with about 165,000 troops involved.

Lee invaded Pennsylvania in June 1863 to take the war out of war-ravaged Virginia, gather supplies, threaten northern cities like Harrisburg or Philadelphia, and pressure Lincoln toward a negotiated peace. The Confederate Army of Northern Virginia totaled about 75,000. The Union Army of the Potomac under General George G. Meade, who took command three days before the battle, totaled about 90,000.

Confederate and Union forces collided north and west of Gettysburg on the morning of July 1, 1863 when Confederate troops searching for shoes encountered Union cavalry under General John Buford. Buford's men held until Union infantry arrived. Confederate forces eventually pushed Union troops through the town to the high ground south. The Union army established a strong defensive line along Cemetery Ridge running south for several miles.

On July 2, Lee attacked the Union flanks. Confederate General James Longstreet's assault on the Union left at Little Round Top, the Wheatfield, and the Peach Orchard nearly succeeded but was repulsed after fierce fighting that included Colonel Joshua Chamberlain's famous bayonet charge with the 20th Maine that saved Little Round Top. Confederate attacks on the Union right at Culp's Hill also failed.

On July 3, Lee ordered the disastrous Pickett's Charge, in which 12,500 Confederate infantry under generals George Pickett, James Pettigrew, and Isaac Trimble attacked the center of the Union line across nearly a mile of open ground. Union artillery and rifle fire devastated the charge; about half the attackers became casualties. Lee withdrew on the night of July 4, 1863.

Total casualties for the three days were approximately 23,000 Union (3,155 killed, 14,529 wounded, 5,365 missing or captured) and 28,000 Confederate (4,708 killed, 12,693 wounded, 5,830 missing or captured). The defeat at Gettysburg combined with the fall of Vicksburg to General Ulysses S. Grant on July 4, 1863 marked the strategic turning point of the war. Lee never invaded the North again. The Confederacy lost the western theater entirely with the surrender at Vicksburg, splitting Confederate territory along the Mississippi River. Lincoln dedicated the Gettysburg National Cemetery on November 19, 1863 with the Gettysburg Address.