The bodies of several Union soldiers lie on the battlefield. This photo is known as "Harvest of Death."
All in all, the battle ended with some 50,000 casualties, making it the bloodiest in U.S. history.
Three Confederate prisoners during the Battle of Gettysburg.
About 8,000 Confederate prisoners were taken at the end of the battle.
The Battle of Gettysburg headquarters of the U.S. Sanitary Commission, a private group that aided sick and wounded Union soldiers during the Civil War.
The body of a sharpshooter, his rifle just out of reach, lies dead on the ground.
A surgeon performs an amputation on a wounded man as others stand by to assist.
A Union soldier who was torn apart by artillery lies dead on the ground.
Several men stand near a battlefield hospital
Confederate bodies lie dead in the area known as the "devil's den."
A hotspot for artillery and sharpshooters, "devil's den" marked one of the battle's bloodiest sites.
The damaged surrounding forest in the immediate aftermath of the Battle of Gettysburg.
Two Union soldiers rest behind defensive fortifications during the Battle of Gettysburg.
Men examine the bodies of two dead sharpshooters.
Cannons sit abandoned after the first day of Battle of Gettysburg.
Cannons played a critical role in the battle, especially on the third day when Confederate forces mistakenly believed that Union cannons had been knocked out but were then devastated on their ensuing offensive.
The bodies of a group of Confederate soldiers wait to be buried.
Some 8,000 soldiers were killed outright on the battlefield.
The headquarters of the Army of the Potomac during the Battle of Gettysburg.
Confederate soldiers who were on the receiving end of a Union shelling.
Gen. Robert E. Lee of the Confederacy.
Lee was ultimately the senior commander of all Confederate military forces.
Gen. George G. Meade of the Union.
Meade was only given command of the Army of the Potomac three days before the Battle of Gettysburg and didn't arrive at the battle until the end of the first day, after which time he was able to organize the Union's victory over the next two days.
Lt. Gen. James Longstreet of the Confederacy.
Lee's right-hand man throughout the war, Longstreet was one of the conflict's most important commanders.
Gen. George Pickett of the Confederacy.
Pickett helped lead the infamous Pickett's Charge that ended with Confederate defeat, turning the tide of the battle and the war against the South.
A field is strewn with the bodies of Confederates.
John L. Burns, a civilian who fought alongside the Union at the Battle of Gettysburg, poses for a photo with his musket.
Burns became famous for fighting despite being 69 at the time.
John L. Burns recovers from his wounds. July 1863.
Dead Confederates lie in the area known as the "slaughter pen" near Little Round Top.
Four soldiers lie dead in the woods near Gettysburg.
People stand in front of the Battle of Gettysburg tents belonging to the U.S. Christian Commission, a group that provided supplies and services to Union troops.
The bodies of several dead horses lie on the battlefield.
Following the battle, some 3,000 horse carcasses were burned, reportedly causing the townsfolk to grow ill from the stench.
The body of a Confederate sharpshooter is left lying where he was shot.
A bridge at nearby Hanover Junction that was burned by the Confederates prior to the Battle of Gettysburg.
The bodies of Confederate dead are gathered for burial.
Union entrenchments on Little Round Top, a hill near the southern end of where the Battle of Gettysburg was fought.
Several bodies lined up for burial.
Crowds gather for the dedication of the Soldiers' National Cemetery (when Abraham Lincoln delivered the Gettysburg Address) in Gettysburg on Nov. 19, 1863.
Abraham Lincoln (identified by red arrow) stands among the crowd before delivering the Gettysburg Address.