On the third day at Gettysburg, roughly 12,500 Confederate soldiers advanced across nearly a mile of open ground toward the Union center on Cemetery Ridge. Union artillery and rifle fire tore the ranks apart; barely half returned. The failed assault, forever known as Pickett's Charge, forced Lee to retreat to Virginia and marked the war's decisive turning point.
The battle's final act began with the largest artillery bombardment of the war, nearly 150 Confederate guns pounding the Union line for almost two hours in an attempt to soften it before the infantry assault. Smoke hung so thick over the fields that gunners on both sides could barely see their targets, and the concussion reportedly rattled windows in towns miles away.
When the cannons fell silent, roughly 12,500 Confederate soldiers under Generals Pickett, Pettigrew, and Trimble stepped out of the treeline and began the long walk toward Cemetery Ridge. Union defenders, dug in behind a low stone wall, watched the gray lines come on with parade-ground precision before opening fire. Canister shot and rifle volleys tore gaps in the formation; a small clump of Confederates briefly breached the wall at the 'Angle' before being overwhelmed in brutal hand-to-hand fighting.
Barely half the attackers made it back to their own lines. Lee reportedly rode out to meet the survivors and told them, 'It is all my fault.' The next day he began his retreat to Virginia. Combined with the Union capture of Vicksburg on July 4th, the twin defeats marked the strategic high-water mark of the Confederacy — the war would grind on for nearly two more years, but the South never again mounted an offensive of this scale.