Gettysburg / Wikipedia

The Battle of Gettysburg (locally /ˈɡɛtɨsbɜrɡ/  ( listen), with an ss sound), fought July 1–3, 1863, in and around the town of Gettysburg, Pennsylvania, was the battle with the largest number of casualties in the American Civil War^[6] and is often described as the war's turning point.^[7] Union Maj. Gen. George Gordon Meade's Army of the Potomac defeated attacks by Confederate Gen. Robert E. Lee's Army of Northern Virginia, ending Lee's invasion of the North.
After his success at Chancellorsville in Virginia in May 1863, Lee led his army through the Shenandoah Valley to begin his second invasion of the North—the Gettysburg Campaign. He intended to move the focus of the summer campaign from war-ravaged northern Virginia and hoped to influence Northern politicians to give up their prosecution of the war by penetrating as far as Harrisburg, Pennsylvania, or even Philadelphia. Prodded by President Abraham Lincoln, Maj. Gen. Joseph Hooker moved his army in pursuit, but was relieved just three days before the battle and replaced by Meade.
The two armies began to collide at Gettysburg on July 1, 1863, as Lee urgently concentrated his forces there. Low ridges to the northwest of town were defended initially by a Union cavalry division, which was soon reinforced with two corps of Union infantry. However, two large Confederate corps assaulted them from the northwest and north, collapsing the hastily developed Union lines, sending the defenders retreating through the streets of town to the hills just to the south.
On the second day of battle, most of both armies had assembled. The Union line was laid out in a defensive formation resembling a fishhook. Lee launched a heavy assault on the Union left flank, and fierce fighting raged at Little Round Top, the Wheatfield, Devil's Den, and the Peach Orchard. On the Union right, demonstrations escalated into full-scale assaults on Culp's Hill and Cemetery Hill. All across the battlefield, despite significant losses, the Union defenders held their lines.
On the third day of battle, July 3, fighting resumed on Culp's Hill, and cavalry battles raged to the east and south, but the main event was a dramatic infantry assault by 12,500 Confederates against the center of the Union line on Cemetery Ridge, known as Pickett's Charge. The charge was repulsed by Union rifle and artillery fire, at great losses to the Confederate army. Lee led his army on a torturous retreat back to Virginia. Between 46,000 and 51,000 Americans were casualties in the three-day battle. That November, President Lincoln used the dedication ceremony for the Gettysburg National Cemetery to honor the fallen and redefine the purpose of the war in his historic Gettysburg Address.

Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.
Now we are engaged in a great civil war, testing whether that nation, or any nation so conceived and so dedicated, can long endure. We are met on a great battle-field of that war. We have come to dedicate a portion of that field, as a final resting place for those who here gave their lives that that nation might live. It is altogether fitting and proper that we should do this.
But, in a larger sense, we can not dedicate -- we can not consecrate -- we can not hallow -- this ground. The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract. The world will little note, nor long remember what we say here, but it can never forget what they did here. It is for us the living, rather, to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us -- that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion -- that we here highly resolve that these dead shall not have died in vain -- that this nation, under God, shall have a new birth of freedom -- and that government of the people, by the people, for the people, shall not perish from the earth.