An estimated 13,000 civil war reenactors from all 50 states and more than a dozen foreign countries were camped out on the Adams County hillsides in Gettsyburg as a record setting attendance of about 100,000 spectators were on-hand during the 150 anniversary of the Battle of Gettysburg held Thursday to Sunday.

The four-day event included numerous battle reenactments involving some 140 cannons and 400 horses representing.

The battle, fought July 1-3 1863, served as a major turning point during the American Civil War by weakening Robert E. Lee's last invasion of the North between the Confederate and Unions forces. It also involved the war's largest number of casualties.

After his advancement at Chancellorsville in Virginia in May 1863, Lee directed his army through the Shenandoah Valley to begin his second invasion of the North, come to be remembered as the Gettysburg Campaign. With his army in zeal, Lee planned to shift the focus of the summer campaign from war-ravaged northern Virginia and hoped to encourage Northern politicians to give up their prosecution of the war by penetrating as far as Harrisburg, Pennsylvania, or even Philadelphia.

Forewarned 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.

Elements of the two armies initially collided at Gettysburg on July 1, 1863, as Lee promptly concentrated his forces there, his goal being to assault the Union army and destroy it.

Between 46,000 and 51,000 soldiers from both armies were casualties in the three-day battle.

On November 19, President Lincoln used the dedication ceremony for the Gettysburg National Cemetery to honor the fallen Union soldiers and reillustrated the aim of the war in his historic Gettysburg Address.